The document surveys the chromium tolerance and bioaccumulation abilities of 51 yeast strains from various genera. The strains were grown in media supplemented with either chromium(III) or chromium(VI) at inhibitory concentrations. Cellular chromium content was then measured. Chromium(III) tolerance ranged from 0.25-5 mM among strains, while chromium(VI) tolerance ranged from 0.1-0.5 mM, with strains generally more sensitive to chromium(VI). Cellular chromium levels varied significantly between strains but followed a general trend of mid-range accumulation of chromium(III) and low-level accumulation of chromium(VI). Electron microscopy showed chromium accumulated in the cytoplasm and organelles of cells.
Mineral-deficient states largely occur in humans and animals because of the nutrition
imbalance. One of the criteria of low copper content in food is a feature of the geological
province which produces agricultural products [4]. One of the criteria of the cell
elemental status regulation of an organism can be associated with the use of probiotic
microorganisms that possess not only high sorption characteristics but also are able to
deposit excessive content of essential elements in the biologically active form. To assess
the perspectives of the application of probiotic microorganisms of the genus Bacillus as
micronutrients we used such methods as the agar basin method relating to diffusion
Copper is an essential metal for normal plant growth and development, although it is also potentially toxic. Copper participates in numerous physiological processes and is an essential cofactor for many metalloproteins, however, problems arise when excess copper is present in cells. Excess copper inhibits plant growth and impairs important cellular processes (i.e., photosynthetic electron transport).The mechanisms involved in the acquisition of this essential micronutrient have not been clearly defined although a number of genes have recently been identified which encode potential copper transporters. The present investigation is an attempt to understand of the copper toxicity and tolerance in rice cultivars, and to compare the ten rice cultivars of Karimganj district of Assam. Copper caused growth reduction in rice and among the screened cultivars Amu Sali seems to be a copper sensitive cultivar.
Article Citation:
Upadhyaya H, Bhattacharjee MK, Deboshree Roy, Soumitra Shome.
Toxic effect of copper on ten rice cultivars.
Journal of Research in Plant Sciences (2011) 1(1): 038-044.
Full Text:
http://www.plantsciences.co.in/documents/PS0011.pdf
Mineral-deficient states largely occur in humans and animals because of the nutrition
imbalance. One of the criteria of low copper content in food is a feature of the geological
province which produces agricultural products [4]. One of the criteria of the cell
elemental status regulation of an organism can be associated with the use of probiotic
microorganisms that possess not only high sorption characteristics but also are able to
deposit excessive content of essential elements in the biologically active form. To assess
the perspectives of the application of probiotic microorganisms of the genus Bacillus as
micronutrients we used such methods as the agar basin method relating to diffusion
Copper is an essential metal for normal plant growth and development, although it is also potentially toxic. Copper participates in numerous physiological processes and is an essential cofactor for many metalloproteins, however, problems arise when excess copper is present in cells. Excess copper inhibits plant growth and impairs important cellular processes (i.e., photosynthetic electron transport).The mechanisms involved in the acquisition of this essential micronutrient have not been clearly defined although a number of genes have recently been identified which encode potential copper transporters. The present investigation is an attempt to understand of the copper toxicity and tolerance in rice cultivars, and to compare the ten rice cultivars of Karimganj district of Assam. Copper caused growth reduction in rice and among the screened cultivars Amu Sali seems to be a copper sensitive cultivar.
Article Citation:
Upadhyaya H, Bhattacharjee MK, Deboshree Roy, Soumitra Shome.
Toxic effect of copper on ten rice cultivars.
Journal of Research in Plant Sciences (2011) 1(1): 038-044.
Full Text:
http://www.plantsciences.co.in/documents/PS0011.pdf
Questions and Answer key for the Botany, Zoology, Physics, Chemistry Medical Code A, Medical Code B, Medical Code C and Medical Code D papers solved by the coaching experts at Sri Chaitanya. Set your sights on the EAMCET, AIIMS and other Medical Entrance exams and start your test preps for 2014 and 2015 entrance examinations. To know more - visit www.srichaitanya.net or call 040 66060606. You can also stay in touch with us at www.facebook.com/SriChaitanyaEducationalInstitutes
Genotoxicity Induced by Food Coloring Dyes on Meristematic Cells Root Tips of...ijtsrd
Food color has a great impact on food consumption and production. Many companies, restaurants and markets use the color perception theory to increase their sales. Recent studies have shown the negative impact of the food colors. So we analyzed the effect of synthetic food colors like orange red, lemon yellow, kesar yellow and apple green on actively dividing root tip cells of Allium cepa. Four different dyes were administered for the treatment of actively dividing root tip cells for 7 day duration along with control. Mitotic analysis clearly revealed the dye induced endpoint deviation like reduction in the frequency of normal divisions in a dose dependent manner. Mitotic divisions in the control sets were found to be normal dye has induced several chromosomal aberrations genotoxic effect at various stages of cell cycle such as stickiness of chromosomes, micronuclei formation, precocious migration of chromosome, unorientation, forward movement of chromosome, laggards, and Chromatin Bridge. Among all, stickiness of chromosomes was present in the highest frequency followed by partial genome elimination as micronuclei. The present study suggests that extensive use of synthetic dye should be forbidden due to genotoxic and cytotoxic impacts on living cells. Thus, there is an urgent need to assess potential hazardous effects of these food colors on other test systems like human and nonhuman biota for better scrutiny. Sheetal Kaur | Priyadarshini Halady | B. Revathi | Lodhi Bushra | Dr. Swapna ""Genotoxicity Induced by Food Coloring Dyes on Meristematic Cells (Root Tips) of Allium Cepa"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd23568.pdf
Paper URL: https://www.ijtsrd.com/biological-science/cytology/23568/genotoxicity-induced-by-food-coloring-dyes-on-meristematic-cells-root-tips-of-allium-cepa/sheetal-kaur
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Regulation of Seed Germination and the Role of Aquaporins under Abiotic StressIJEAB
Aquaporins play a major role in governing the movement of water between neighboring cells during seed germination and are major players in response to abiotic stress conditions that affect water availability. Seeds of pea (Pisum sativum L. cv. Arkel) were used for studying cell growth, expression and function of aquaporins during seed imbibition, radicle emergence and growth.Water channel functioning checked by inhibitory test with mercuric chloride showed closed water channels prior to growth initiation. Addition of mercury scavenging agents dithiothreitol and β-mercaptoethanol along with the HgCl2 overcame the observed inhibitory effects in terms of moisture content. The presence of aquaporin inhibitors (HgCl2 and ZnCl2) and NaCl reduced seedling growth. Here we studied expression of a plasma membrane intrinsic protein (PsPIP1;2) and a tonoplast intrinsic protein (PsTIP1;1) by using the semi quantitative RT-PCR in the germinated seedlings exposed to different abiotic stresses. Treatment with NaCl, HgCl2 and ZnCl2 differentially regulated gene expression in radicle, cotyledon and plumule. NaCl and Hg, upregulated expression of PsPIP1;2 and PsTIP1;1 in radicle and expression of PsTIP1;1 was significantly upregulated in radicle and suppressed in cotyledon by Zn. A possible role for aquaporins in germinating seeds and seedling response to abiotic stresses is discussed.
Very important multiple choice question on Industrial Microbiology
Subscribe this you tube channel for more videos on Microbiology and MCQs
https://www.youtube.com/channel/UCxqXy8R-dkqodPMXnXvE8pQ
Questions and Answer key for the Botany, Zoology, Physics, Chemistry Medical Code A, Medical Code B, Medical Code C and Medical Code D papers solved by the coaching experts at Sri Chaitanya. Set your sights on the EAMCET, AIIMS and other Medical Entrance exams and start your test preps for 2014 and 2015 entrance examinations. To know more - visit www.srichaitanya.net or call 040 66060606. You can also stay in touch with us at www.facebook.com/SriChaitanyaEducationalInstitutes
Genotoxicity Induced by Food Coloring Dyes on Meristematic Cells Root Tips of...ijtsrd
Food color has a great impact on food consumption and production. Many companies, restaurants and markets use the color perception theory to increase their sales. Recent studies have shown the negative impact of the food colors. So we analyzed the effect of synthetic food colors like orange red, lemon yellow, kesar yellow and apple green on actively dividing root tip cells of Allium cepa. Four different dyes were administered for the treatment of actively dividing root tip cells for 7 day duration along with control. Mitotic analysis clearly revealed the dye induced endpoint deviation like reduction in the frequency of normal divisions in a dose dependent manner. Mitotic divisions in the control sets were found to be normal dye has induced several chromosomal aberrations genotoxic effect at various stages of cell cycle such as stickiness of chromosomes, micronuclei formation, precocious migration of chromosome, unorientation, forward movement of chromosome, laggards, and Chromatin Bridge. Among all, stickiness of chromosomes was present in the highest frequency followed by partial genome elimination as micronuclei. The present study suggests that extensive use of synthetic dye should be forbidden due to genotoxic and cytotoxic impacts on living cells. Thus, there is an urgent need to assess potential hazardous effects of these food colors on other test systems like human and nonhuman biota for better scrutiny. Sheetal Kaur | Priyadarshini Halady | B. Revathi | Lodhi Bushra | Dr. Swapna ""Genotoxicity Induced by Food Coloring Dyes on Meristematic Cells (Root Tips) of Allium Cepa"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd23568.pdf
Paper URL: https://www.ijtsrd.com/biological-science/cytology/23568/genotoxicity-induced-by-food-coloring-dyes-on-meristematic-cells-root-tips-of-allium-cepa/sheetal-kaur
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Regulation of Seed Germination and the Role of Aquaporins under Abiotic StressIJEAB
Aquaporins play a major role in governing the movement of water between neighboring cells during seed germination and are major players in response to abiotic stress conditions that affect water availability. Seeds of pea (Pisum sativum L. cv. Arkel) were used for studying cell growth, expression and function of aquaporins during seed imbibition, radicle emergence and growth.Water channel functioning checked by inhibitory test with mercuric chloride showed closed water channels prior to growth initiation. Addition of mercury scavenging agents dithiothreitol and β-mercaptoethanol along with the HgCl2 overcame the observed inhibitory effects in terms of moisture content. The presence of aquaporin inhibitors (HgCl2 and ZnCl2) and NaCl reduced seedling growth. Here we studied expression of a plasma membrane intrinsic protein (PsPIP1;2) and a tonoplast intrinsic protein (PsTIP1;1) by using the semi quantitative RT-PCR in the germinated seedlings exposed to different abiotic stresses. Treatment with NaCl, HgCl2 and ZnCl2 differentially regulated gene expression in radicle, cotyledon and plumule. NaCl and Hg, upregulated expression of PsPIP1;2 and PsTIP1;1 in radicle and expression of PsTIP1;1 was significantly upregulated in radicle and suppressed in cotyledon by Zn. A possible role for aquaporins in germinating seeds and seedling response to abiotic stresses is discussed.
Very important multiple choice question on Industrial Microbiology
Subscribe this you tube channel for more videos on Microbiology and MCQs
https://www.youtube.com/channel/UCxqXy8R-dkqodPMXnXvE8pQ
Asopos is a river that rises in Viotia and discharges into the South Euboea Gulf in Greece, about 60 km north of Athens.Forty years ago, in 1969, through a Presidential Decree, issued by the Military Government (Junta) that ruled Greece at the time, Asopos was proclaimed a Processed Industrial Waste receiver. The river the Ancient Greeks worshiped as a god (Asopos was Poseidon’s son) was unfortunate enough to run through areas that turn out almost 20% of Greece’s total industrial production.
Today, Asopos’ waters receive waste from hundreds of industries, situated at a nearby Industrial area. Nevertheless, only a slight amount of water reaches its estuary. The texture of the soil absorbs the largest part of the water, including all the industrial waste, and spreads it to the whole underground water. This results to a possibly irreversible pollution of a huge area with various waste, amongst which heavy metals, including the renowned due to recent publicity, Hexavalent Chromium. This is an element that causes cancer and/or mutations.
The water from the springs, the fountains and the drillings in this whole area is no longer suitable for any human use, neither drinking nor cooking, bathing and washing clothes, not even for watering plants!
Hundreds of thousands of residents inhabit the area, especially during the summer. All these people have been consuming water for years, without ever having been officially informed of the hazards, until early this summer (2007).
Recently, after 3 adjournments and a delay of 6 years, a trial took place. 10 out of 18 defendants were acquitted due to misrecorded data! For those convicted, the highest punishment was the ridiculous amount of EURO 5000 as a fine!
Various reportings have revealed that some industries open up drillings and convey inside all their waste- directly into the underground water!
We request that the Greek Government, the Greek Parliament, the European Community Authorities and every other qualified service take all necessary measures and actions in order to insure the restoration of Asopos river, as well as the indemnification of all the problems (health related, economical, environmental) the residents are facing due to this situation.
Project Management Challenges in an Effluent Treatment Plant Construction PRABHASH GOKARN
Tata Steel operates India’s largest chromite mines at the Sukinda Valley in Odisha producing chrome ore which is subsequently converted it to Ferro Chrome and sold to customers across the world. A large quantity of water, generated during mining and due to rainfall, needs to be handled during the mining operations. Chrome Ore mainly contains tri-valent Chromic oxide and a very small fraction of hexavalent di-chromate. Water coming in contact with chromium ore preferentially leaches out soluble hexavalent chromium from the ore body, as a result, water from the mine contains 0.2 – 4 mg/l of hexavalent chromium against a safe limit of 0.005 mg/l for human consumption; requiring all water to be treated before its release from the mines. Thus, Tata Steel is setting up an effluent plant at Sukinda with a capacity of 108 million litres/day; perhaps one of the largest in the region; which will be complete by end June 2015.
Adsorption of cr (vi) from aqueous environment using neem leaves powdereSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Worked with different particle size of coffee as an antioxidant to find which size creates a reaction at a faster rate in the reduction of Chromium IV to Chromium III.
2. evaluation of remediation in heavy metal tolerance and removal by comamona...Darshan Rudakiya
Comamonas acidovorans has vital role in degradation of natural as well as complex organic compounds. Comamonas acidovorans MTCC 3364 is mainly used for bioconversion of different steroids but now it is a novel approach on bioremediation. In heavy metals hexavalent chromium, mercury and lead is very toxic and carcinogenic for human health. Organism can tolerate heavy metals like hexavalent chromium, mercury, lead and aluminium with high efficiency. Removal of hexavalent chromium is major problem to textile as well as different industries. Comamonas acidovorans MTCC 3364 removed 99% of the hexavalent chromium from the medium and it can tolerate up to 600 ppm of chromium and 200 ppm of mercury in solidified medium. This organism shows high tolerance against salt i.e. it can tolerate up to 10% of salt. Chromium removal was also observed by using biosorption studies and MIC method. This bacteria increases pH during removal of chromium and makes chromium oxide which is trivalent chromium; it is a non-toxic compound. High salt tolerance, heavy metal tolerance and removal of hexavalent chromium make applicability in the treatment of waste water technology and treatment of industrial effluent which contain high amount of salt and heavy metals.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability
Removal of Cr (VI) Through the Use of the Agroindustrial Residue of the Perse...CrimsonpublishersMCDA
We analyzed the Chromium (VI) removal capacity in aqueous solution by the Persea americana biomass, using the diphenyl carbazide method to evaluate the metal concentration. Biosorption at different pH (1, 2, 3, and 4) was evaluate for different times. We too studied the effect of temperature in the range of 28 to 60 °C and the removal at different initial concentrations of Cr (VI) of 200 to 1000mg/L. Therefore, the highest biosorption of the metal (50mg/L) occurs within 270 minutes, at pH of 1.0 and 28 °C. According to temperature, the highest removal was observing at 60 °C, in 45 minutes, when the metal is completely adsorbed. At the analyzed concentrations of Cr (VI), fungal biomass, showed excellent removal capacity, besides it removes efficiently the metal in situ (100% removal in earth and water contaminated, after 5 and 6 days of incubation, 5 and 10g of biomass, 10g of earth and 100mL of water; so, it can be used to eliminate it from industrial wastewater.
https://crimsonpublishers.com/mcda/fulltext/MCDA.000570.php
For more open access journals in Crimson Publishers please click on link: https://crimsonpublishers.com
For more articles on journal of agronomy and crop science please click on below link: https://crimsonpublishers.com/mcda/
Heavy metals, particularly silver and mercury, have a variety of applications in controlling microbial population. Ps. aeruginosa is a high intrinsic resistant to antibiotics and heavy metals including Copper Sulfate, Silver Sulfate, Mercury chloride, Lead nitrate, Zinc sulfate, Cadmium sulfate, and Nickel sulfate.
In-Vitro Evaluation of Heavy Metal Tolerance and Biosorptive Potential of Two...semualkaira
Heavy metal contamination now a day is one of the major global
environmental concerns and industrial effluent is commonly used
for irrigation. Increasing industrial rate in the modern world is responsible for increase in concentration of heavy metals. Present
study was designed to isolate and identify some indigenous heavy
metal tolerant bacteria from textile effluents.
In-Vitro Evaluation of Heavy Metal Tolerance and Biosorptive Potential of Two...semualkaira
Heavy metal contamination now a day is one of the major global
environmental concerns and industrial effluent is commonly used
for irrigation. Increasing industrial rate in the modern world is responsible for increase in concentration of heavy metals. Present
study was designed to isolate and identify some indigenous heavy
metal tolerant bacteria from textile effluents.
An investigation on heavy metal tolerance properties of bacteria isolated fro...AbdullaAlAsif1
The presence of high concentration of toxic heavy metals in industrial waste directly leads to contamination of receiving soil and water bodies and has deleterious impact on both human health and aquatic life. In the present study samples from textile mill effluent from different areas of Jessore city were analyzed for the identification and characterization of bacteria which shows tolerance to Copper, Mercury and Zinc. The bacterial isolates were characterized on the basis of their morphological and physiological studies including size and shape of the organisms, arrangement of the cells, presence or absence of spores, regular or irregular forms, gram reaction, cultural characteristics, IMViC test, H 2S production, nitrate reduction, deep glucose agar test etc. All the bacterial isolates belonged to 3 genera Bacillus, Enterobacter and Pseudomonas. All the gram positive isolates used in our study showed highest level of tolerance to Zn and moderate level of tolerance to Cu while gram negative isolates showed higher tolerance to Zn in comparison with Cu in nutrient broth. But all of the isolates showed almost no tolerance to Hg. So, our bacterial isolates have the probability to use in the treatment of industrial effluent containing heavy metals and thus pollution due to heavy metal can be controlled. The goal of this study was to identify heavy metal tolerant bacteria from the textile effluent. This kind of study is very significant for broader investigation to obtain data about metal tolerant bacteria considering their potential use for bioremediation and about the interactions between metals and bacteria.
Atmospheric Exposure to Cr III Powder Causes Genotoxicity in Rattus Norvegicus.inventionjournals
Several chemical elements are responsible for altering the genetic integrity of living beings. The metal Cr stands out in this regard. It exists in two oxidation states, Cr VI and Cr III, and has been investigated as an important environmental and occupational contaminant. Although the former is considered carcinogenic, the latter is classified as safe, even for human use in food supplementation. However, most studies with Cr( III) have been carried out by different routes to how it is occupationally found – in the atmosphere. This study evaluated the genotoxicity of Cr(III) inhaled during 8 hours of exposure to the maximum concentration permitted by ATSDR. Fifteen male Rattus norvegicus were used in this study. There were 3 groups (n=5 per group); these were - group exposed to Cr (III) powder (S), the negative control group (NC) and the positive control group (PC). The animals were exposed to Cr aerosol particles at a flow rate of 9L/min and atmospheric concentration of 500μg/m3 for only 8 hours in this study. An increase in genotoxicity and mutagenicity in the group exposed to the metal powder was observed. These findings suggest that further studies should be carried out in order to establish safe levels of exposure to Cr III in work environments
Virulence Phenotype, Physicochemical Properties and Biofilm Formation of Pseu...IJERA Editor
Potable water piping has been demonstrated to serve as a reservoir for opportunistic pathogens bacteria such as Pseudomonas aeruginosa. In this report, we describe the characterization of P. aeruginosa strains isolated from water intended for human consumption by the presence of virulence factors. These strains expressed their suitability for adhesion and the formation of biofilms on polyethylene (PE). Also In this work, we were able to elucidate the factors intervening in adhesion and biofilm formation by showing the role of the substrate, the environment and bacteria. Strong correlation was observed between physicochemical properties especially the electron donor property and the surface percentage covered by cells. These results indicate that this property plays a crucial role in Pseudomonas aeruginosa adherence on the PE surface. In addition, if no relationship was found between the adhesion results and hydrophobicity, it means that this property was not involved in the adhesion process of Pseudomonas aeruginosa on the PE surface.
GraphSummit Singapore | The Future of Agility: Supercharging Digital Transfor...Neo4j
Leonard Jayamohan, Partner & Generative AI Lead, Deloitte
This keynote will reveal how Deloitte leverages Neo4j’s graph power for groundbreaking digital twin solutions, achieving a staggering 100x performance boost. Discover the essential role knowledge graphs play in successful generative AI implementations. Plus, get an exclusive look at an innovative Neo4j + Generative AI solution Deloitte is developing in-house.
How to Get CNIC Information System with Paksim Ga.pptxdanishmna97
Pakdata Cf is a groundbreaking system designed to streamline and facilitate access to CNIC information. This innovative platform leverages advanced technology to provide users with efficient and secure access to their CNIC details.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
A tale of scale & speed: How the US Navy is enabling software delivery from l...sonjaschweigert1
Rapid and secure feature delivery is a goal across every application team and every branch of the DoD. The Navy’s DevSecOps platform, Party Barge, has achieved:
- Reduction in onboarding time from 5 weeks to 1 day
- Improved developer experience and productivity through actionable findings and reduction of false positives
- Maintenance of superior security standards and inherent policy enforcement with Authorization to Operate (ATO)
Development teams can ship efficiently and ensure applications are cyber ready for Navy Authorizing Officials (AOs). In this webinar, Sigma Defense and Anchore will give attendees a look behind the scenes and demo secure pipeline automation and security artifacts that speed up application ATO and time to production.
We will cover:
- How to remove silos in DevSecOps
- How to build efficient development pipeline roles and component templates
- How to deliver security artifacts that matter for ATO’s (SBOMs, vulnerability reports, and policy evidence)
- How to streamline operations with automated policy checks on container images
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
Maruthi Prithivirajan, Head of ASEAN & IN Solution Architecture, Neo4j
Get an inside look at the latest Neo4j innovations that enable relationship-driven intelligence at scale. Learn more about the newest cloud integrations and product enhancements that make Neo4j an essential choice for developers building apps with interconnected data and generative AI.
Communications Mining Series - Zero to Hero - Session 1DianaGray10
This session provides introduction to UiPath Communication Mining, importance and platform overview. You will acquire a good understand of the phases in Communication Mining as we go over the platform with you. Topics covered:
• Communication Mining Overview
• Why is it important?
• How can it help today’s business and the benefits
• Phases in Communication Mining
• Demo on Platform overview
• Q/A
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
GraphSummit Singapore | The Art of the Possible with Graph - Q2 2024Neo4j
Neha Bajwa, Vice President of Product Marketing, Neo4j
Join us as we explore breakthrough innovations enabled by interconnected data and AI. Discover firsthand how organizations use relationships in data to uncover contextual insights and solve our most pressing challenges – from optimizing supply chains, detecting fraud, and improving customer experiences to accelerating drug discoveries.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
Full-RAG: A modern architecture for hyper-personalizationZilliz
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7
1. Process Biochemistry 40 (2005) 1565–1572
www.elsevier.com/locate/procbio
Chromium(III) and (VI) tolerance and bioaccumulation in yeast:
a survey of cellular chromium content in selected strains
of representative genera
H. Ksheminskaa, D. Fedorovycha, L. Babyaka, D. Yanovycha,
P. Kaszyckib, H. Koloczekb,*
a
Institute of Cell Biology, National Academy of Science of Ukraine, Dragomanov Street 14/16, 79005 Lviv, Ukraine
b
´
University of Agriculture, Biochemistry Department, Al. 29 Listopada 54, 31-425 Krakow, Poland
Received 10 September 2003; accepted 16 May 2004
Abstract
Fifty-one wild type, naturally occurring yeast strains belonging to various systematic groups were screened for chromium(III) and (VI)
uptake at growth-inhibitory concentrations of the metal. Yeast cells were supplemented with Cr at the moment of inoculation with 0.03 mg
d.w. biomass/ml and then cultivated for 3 days in optimal growth media. The tolerance to Cr varied depending on the strain tested and the yeast
cultures proved to be generally more sensitive to Cr(VI) (concentration range: 0.1–0.5 mM) than to Cr(III) (0.25–5 mM). The levels of cellular
Cr content ranged from 0.29 to 11.10 mg/g d.w. and 0.21–3.3 mg/g d.w. for Cr(III) and Cr(VI), respectively. Distribution diagrams of the cell-
accumulated Cr were constructed for the tested strain population, and the general uptake tendency of middle-range amounts of Cr(III), and
low-range levels of Cr(VI) was revealed. The cell-accumulated Cr levels were similar at identical, non-toxic concentrations of either Cr form
supplemented to the medium. Electron microscopic images proved that cytoplasm and cellular organelles were the ultimate targets for
accumulation of both valences of the metal. The extreme cases of the strains revealing either the lowest or the highest Cr tolerance and uptake
capabilities are discussed in terms of possible bioremediation mechanisms. The applicability of the strains in both environmental and
nutritional practice was also considered.
# 2004 Elsevier Ltd. All rights reserved.
Keywords: Chromium bioremediation; Cr(VI) and Cr(III) toxicity; Yeast survey
1. Introduction oxidation states of this element, ranging from 2À to 6+, the
most common and stable are Cr(VI) and Cr(III). Both forms
Chromium uptake and bioremediation by yeast are gain- are excessively released into the environment; for example
ing much attention since these eukaryotic microorganisms Cr(III) prevails in effluents from tanneries and pigment-
have proved to be useful in biotechnological practice. Yeast producing plants whereas the sources of Cr(VI) are, among
has been applied in the management of Cr-containing waste others: metallurgy, mining, fossil fuel combustion, wood
as well as in nutritional supplementation of this trace metal. preservation and cooling installation effluents [2].
Environmental risk caused by Cr contamination is due to a Cr(VI) compounds are known to be extremely toxic to
variety of industrial applications of chromium, which lead living organisms, causing allergies, eczema, irritations, and
finally to heavy pollution of soils, ground and surface waters, respiratory track disorders [2,4]; they are also strongly
and the atmosphere [1]. The chemistry of environmentally- mutagenic and cancerogenic [5,6]. This toxic action is
released Cr compounds is very complex [2,3]. Among many due to the negatively charged hexavalent Cr ion complexes
which can easily cross cellular membranes by means of
* Corresponding author. Tel.: +48 12 413 38 74; fax: +48 12 413 38 74. sulfate ionic channels [7], and then undergo immediate
E-mail address: koloczek@ogr.ar.krakow.pl (H. Koloczek). reduction reactions leading to formation of various reactive
0032-9592/$ – see front matter # 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.procbio.2004.05.012
2. 1566 H. Ksheminska et al. / Process Biochemistry 40 (2005) 1565–1572
intermediates [8–10]. These intermediates are themselves of Sciences, Lviv, Ukraine. Strain descriptions are given
harmful to cell organelles, proteins and nucleic acids according to the nomenclature used by appropriate source
[5,11,12]. collections.
Cr(III) has also been shown to negatively affect cellular Yeast cultures were grown in optimal (rich) liquid media,
structures [5,7,13]; however, its toxicity observed in vivo is at a pH of 5.0, containing (per litre): 20 g glucose, 3 g
much lower as compared to Cr(VI). This fact can be (NH4)2SO4, 0.5 g KH2PO4, 0.2 g MgSO4Á7H2O, 0.2 g
accounted for by the presence of positively charged com- CaCI2Á6H2O, 2 g yeast extract, 2 g peptone, and 2 mg biotin.
plexes that are the predominant form of trivalent Cr, which The source of iron (0.2 mg/l) was provided by Mohr salts.
are much less soluble and less suitable for transport inside Cells were inoculated at low biomass densities (approxi-
cells. Still, the organically-bound Cr(III) derivatives might mately 0.03 mg d.w./ml). Yeast cells were grown in 100 ml
also be transported across cell membranes by some as yet Erlenmeyer flasks on a gyro-shaker (200 rpm) at 30 8C for
unknown mechanism, as pointed out by Raspor et al. [13] three days. Biomass was checked turbidimetrically, as opti-
and Srivastava et al. [14]. cal density at 540 nm (OD540). Yeast dry mass, expressed in
On the other hand, trivalent Cr has been found to be an mg per ml of the cell suspension, was calculated based on the
essential trace element involved in protein structure stabi- appropriate calibration curves as OD540 Â Dilution/1.9.
lisation and lipid and glucose metabolism [15,16]. Dietary Viability studies were made by cell surface plating on Petri
Cr requirements for humans have been determined as 25– dishes and incubating for 48 h in optimal media containing
50 mg per day and the most convenient natural source of the 2% bacto-agar.
metal seems to be the non-toxic and stable organically-
bound Cr present in chromium-enriched biomass. 2.2. Incubation with Cr(VI) and Cr(III)
As a useful means for bioremediation of environmental
chromium contamination, yeasts were used to treat Cr- Sterile chromium salt stock solutions (100 mM), Cr(VI)
containing effluents in order to remove toxic compounds — K2Cr2O7, and Cr(III) — Cr2(SO4)3Á16H2O were added
from waters and soils [17–23]. They were also found to be directly to the cultivation media at concentrations given in
very suitable organisms capable of conducting a bioprocess Section 3. Cr(III) was soluble at a cultivation media pH of
aimed at obtaining chromium-enriched biomass used for 5.0. This acidity prevented trivalent chromium from forming
balanced nutrition of mammals and humans [13,24]. In complexes and olation ([13] and our observations). For each
particular, yeasts which are found effective in accumulation strain tested, the level of Cr(III) and Cr(VI) supplemented to
of aggressive Cr compounds and able to bioconvert them the medium was growth-inhibitory, i.e. it led to a 40–60%
into stable, non-toxic and bioavailable forms might be inhibition of yeast culture density growth at the cultivation
employed for successful environmental control. conditions described above. In order to determine the appro-
The aim of this study is to screen a variety of yeast genera priate Cr concentrations to be applied, preliminary chro-
in terms of Cr(III) and Cr(VI) uptake capacity using cell mium-sensitivity tests were performed for all of the strains,
cultures cultivated at optimal conditions, in the presence of as typically presented in Fig. 1. Cell viability checks proved
growth-inhibitory chromium concentrations. that in all ofcases incubation with sublethal Cr concentra-
tions had no impact on cell survival. Determination of the Cr
level in yeast cells was performed in samples containing
2. Materials and methods approximately 50–100 mg d.w. of yeast. Cells were washed
three times with distilled water. Specimens were wet-miner-
2.1. Yeast strains, growth conditions and viability studies alised by gently heating in a nitric acid/hydrogen peroxide
solution. The total chromium content was determined by
Fifty-one yeast strains that were used in the study are listed means of atomic absorption spectroscopy (AAS) using a
in Table 1. The strains represent various systematic groups Varian spectrometer model Spectr AA-20B. In several cases,
such as Saccharomyces, Zygosaccharomyces, Pichia, Can- Cr determinations were confirmed by the technique of
dida, Debaryomyces, Schwanniomyces, Cryptococcus, Kluy- spectrofluorimetric measurement of the fluorescent probe
veromyces, Hansenula and several others. They were PTQA (2-(a-pyridyl)thioquinaldinamide) [25] with a Hita-
obtained from the yeast strain collections: American Type chi model F-4500 spectrofluorimeter. The analyses of cel-
Culture Collection (ATCC), Halle University Collection, lular Cr accumulation were performed for at least three
Germany (H), Collection of the Institute of Biochemistry independent experimental runs.
and Physiology of Microorganisms, Pushchino, Russia
(IBPhM), National Collection of Yeast Cultures, UK 2.3. Electron microscopy
(NCYC), Russian General Collection of Microorganisms
(Vsierossijskaja Kollekcija Mikroorganizmov, VKM), and Microscopic images were obtained with a TESLA elec-
Centraal Bureau voor Schimmelcultures, Baarn, Holland tron microscope, model BS 500. The specimens of 24 h cell
(CBS). The other strains were obtained from the laboratory cultures were fixed with glutaraldehyde and were not further
collection of the Institute of Cell Biology, National Academy contrasted in order to avoid generating imaging artefacts.
4. 1568 H. Ksheminska et al. / Process Biochemistry 40 (2005) 1565–1572
d.w., respectively). On the other hand, in chromium sensitive
C. parapsilosis CBS 88 and C.macedoniensis Y-1507, rela-
tively low levels of cellular chromium were determined
(0.70 and 0.51 mg/g d.w., respectively). The highest
amounts of Cr(III) taken up by the cultures were obtained
for C.curvata Y-39 (11.10 mg/g d.w.) and Candida sp. Y-454
(7.53 mg/g d.w.), and both strains were found to be resistant
to trivalent Cr (5 and 4 mM, respectively).
For the case of Cr(VI), all of the sensitive strains (below
0.2 mM Cr(VI)) showed weak chromate uptake (<0.6 mg/g
d.w.). The tolerant strain Pichia guilliermondii Y-1256
(grown at 0.5 mM Cr(VI)) revealed unusually low Cr con-
tent (0.28 mg/g d.w.). Among the mostly efficient accumu-
lators were Kluyveromyces bulgaricus Y-1494 and K. lactis
Y-1527, which revealed the levels of 3.05 and 3.30 mg/g
d.w. determined after growth in the presence of 0.4 and
0.3 mM Cr(VI), respectively.
When the uptake tendency of both Cr valences is con-
Fig. 1. Growth inhibition of P. guilliermondii ATCC 201911 cultures
treated with chromium(VI) at concentrations 0.125 mM (a), 0.25 mM sidered, there appears to be no correlation for most of the
(b), 0.5 mM (c), 0.75 mM (d), and 1 mM (e). (D) growth kinetics in the strains. In this respect, however, K. lactis Y-1527 stands out,
absence of Cr, at optimal medium conditions. as an example of a strain capable of accumulating high levels
of both Cr(III) and Cr(VI) (see Table 1). At the same time,
such strains as Pichia pastoris NCYC 175 (cellular Cr
yeast tested (see Fig. 1 for an example). For the case of content: 0.29 mg Cr(III)/g d.w. and 0.32 mg Cr(VI)/g
Cr(III), the concentration ranged from 0.25–5 mM, and for d.w.) and Hansenula polymorpha NCYC 2309 (0.66 mg
Cr(VI), from 0.1–0.5 mM. The screening of the yeast cell Cr(III)/g d.w. and 0.40 mg Cr(VI)/g d.w. revealed rather a
sensitivity to chromium(III) and chromium(VI) and of the poor uptake of both Cr forms.
uptake of the metal after a 3-day incubation is given in Table The distribution characteristics of the strains tested in
1. Cellular levels of Cr accumulated by the yeast cultures Table 1, based on the cell accumulation data, are presented
showed some dependence on the initial concentration of the in Figs. 2 and 3. In Fig. 2, the strains have been grouped
metal in the medium; however, various strains revealed a according to the cellular chromium content of Cr(III) (Fig.
wide range of uptake capabilities. In particular, several 2A) and Cr(VI) (Fig. 2B), as indicated in the figure legend.
strains are listed which exhibited unusual characteristics Fig. 3 presents the distribution map where the coordinates of
regarding chromium tolerance and/or uptake. For the case of each strain are expressed as the levels of cell-accumulated
Cr(III), Kluyveromyces thermotolerans VKM Y-894, Can- Cr(III) and Cr(VI).
dida membranaefaciens Y-918 and Y-1510 were found to be Electron microphotographs obtained for Pichia guillier-
chromium sensitive (50% growth-inhibition at 0.5 mM con- mondii ATCC 201911 after 24 h exposure to inhibitory
centration), yet, they tended to accumulate relatively high chromium concentrations are shown in Fig. 4. The cells,
cellular levels of the metal (3.95, 3.33, and 1.91 mg Cr/g grown to a density of 1 mg d.w./ml, were incubated with
Fig. 2. Frequency distribution of strains as tested in Table 1. based on the level of cell-accumulated chromium. Each bar represents the number of strains which
accumulated Cr within the concentration ranges (in mg of Cr per g dry weight): panel A — Cr(III): 0–0.5 (a), 0.51–1.0 (b), 1.1–1.5 (c), 1.6–2.0 (d), 2.1–2.5 (e),
2.6–3.0 (f), 3.1–3.5 (g), 3.6–4.0 (h), and >4.0 (i); panel B — Cr(VI): 0–0.25 (a), 0.26–0.50 (b), 0.51–0.75 (c), 0.76–1.0 (d), 1.1–1.25 (e), 1.26–1.5 (f), 1.51–1.75
(g), 1.76–2.0 (h), and >2.0 (i).
5. H. Ksheminska et al. / Process Biochemistry 40 (2005) 1565–1572 1569
are based on the cell culture physiological response to
chromium. Therefore, the concentrations of both Cr(III)
and Cr(VI) used to treat yeast cultures varied several fold.
In order to compare cellular uptake of both chromium forms,
in several cases identical levels of Cr(III) and Cr(VI) were
applied. The results obtained for selected strains are pre-
sented in Fig. 5. Note that out of the three strains tested, only
P. pastoris NCYC 175 grown in the presence of 0.5 mM
Cr(III) and Cr(VI) accumulated the hexavalent form more
efficiently than the trivalent form. In the other cases (P.
angusta NCYC 2311, H. polymorpha NCYC 2309) similar
levels of cellular chromium were obtained.
4. Discussion
Yeasts are a very diverse group of eukaryotic microor-
ganisms [26,27] and the studies of their interaction with
Fig. 3. Yeast strain distribution diagram based on the levels of cell-
accumulated Cr(III) and (VI), as given in Table 1. The insert reveals the chromium and other heavy metals may reveal different
positions of two additional strains with exceptionally high levels of cellular resistance and bioremediation strategies. The aim of this
Cr(III): Candida sp. IBPhM Y-454 (7.53 mg/g d.w.) and C. curvata VKM Y- study was to compare a number of yeasts of various genera
39 (11.10 mg/g d.w.). in terms of their sensitivity to, and the uptake potential for
Cr(III) and Cr(VI), as revealed by living biomass cultivated
at optimal conditions in liquid rich growth media. Our data
4 mM Cr(III) (Fig. 4B) and 1 mM Cr(VI) (Fig. 4C). The indicate profound differences within the group of the yeast
example of a control image (absence of chromium in the strains studied, which is in agreement with other observa-
medium) is shown in Fig. 4A, where typical round-shaped tions [13] where the diversity was found not only among
cells can be seen with poorly visible cellular structures. It different genera but even between the strains belonging to
should be stressed that the images were obtained after the same taxonomic group. The results of this paper also give
specimen fixation with glutaraldehyde only, and that no evidence against the view of some authors that metal uptake
contrasting techniques, involving any heavy metal, were depends mainly on surface binding mechanisms rather than
applied, which could have interfered with the chromium- on metabolic activity [28].
rich regions and thus could have generated possible imaging Experimental work presented here provides, for the first
artefacts. The photographs in sections B and C reveal the time, a systematic survey on yeast of representative genera.
effect of chromium on cellular structures as well as the In a complementary study, similar screening involving
possible intracellular targets for the bioremediated metal. various yeast genera was made by Batic et al. [29]; however,
Significant changes in cellular interior contrast and density the work focused on Cr(III) toxicity rather than Cr accu-
could be observed after interaction with both Cr(III) and mulation, and, unlike our tests done in liquid media, the
Cr(VI) compounds indicating the intracellular deposition of experiments were performed using the technique of surface
chromium. In the case of Cr(III) presence (Fig. 4B), the plating on solid media. The studies on chromium tolerance
cellular organelles were much more structured relative to the and interaction with yeast, as published by other authors,
control, and it was typical to observe dark entities (grains), were usually limited to the strains of single, selected sys-
located preferentially in the vacuole, which seem to be the tematic groups. So far, the most extensively examined yeasts
end-effects of Cr(III) accumulation. The trivalent form of the were Saccharomyces sp., Schwanniomyces occidentalis (see
metal, however, did not affect the general appearance and [13] and the references therein) and the environmental
shape of the cells. isolates of Candida sp. and Rhodotoruloides sp. [7,17,30].
The addition of Cr(VI) (Fig. 4C) to the culture medium More recently, bioremediation of chromium was studied
resulted in the formation of similar structures in the cell with Candida intermedia [24], C. utilis [31] as well as with
interior and the appearance of the dark grains found in wild-type and mutant strains of Schizosaccharomyces
regions which could be identified as vacuole. However, pombe [32], and Pichia guilliermondii [33].
these grains were much sharper and denser in relation to The uptake of chromium strongly depends on a variety of
Cr(III) supplementation. Hexavalent chromium was also factors, with the metal valence, concentration and the nature
found to affect yeast cell morphology, causing irregular of the chemical complex of Cr itself being the most impor-
shape, as exemplified by the left-hand image of Fig. 4C. tant. The cellular content of this metal has also been proved
As indicated earlier, the accumulation data presented in to be dependent upon the cultivation mode [13,24], media
Table 1 were obtained at growth-inhibitory conditions that composition and availability of energy source metabolites
6. 1570 H. Ksheminska et al. / Process Biochemistry 40 (2005) 1565–1572
Fig. 4. Electron microscopic images of P. guilliermondii ATCC 201911 cultivated at control conditions (A) and incubated for 24 h with chromium: 4 mM
Cr(III) (B) (Cr cellular level; 0.83 mg/g d.w.), and 1 mM Cr(VI) (C) (Cr cellular level; 0.53 mg/g d.w.). Bars: 1 mm.
7. H. Ksheminska et al. / Process Biochemistry 40 (2005) 1565–1572 1571
of the strains (n = 27) were found to exhibit relatively low
uptake capabilities (0.25–0.5 mg/g d.w.).
Based on the data presented in this paper it is not likely
that the problem of Cr toxicity is closely and exclusively
related to Cr overaccumulation, as suggested by several
authors [7,13,17,22,36]. Among the yeasts examined, sev-
eral strains can be found which were tolerant to Cr and were
still able to accumulate high levels of the metal (see Section
3 and Table 1).
At the same time, the results of this study may enable
strains to be chosen for further bioremediation research
Fig. 5. Cellular chromium uptake obtained after treatment with Cr(III) which should include characterisation of Cr(III) and Cr(VI)
(light bars) and Cr(VI) (dark bars) at identical concentrations of the metal transport and/or biosorption, metabolism of Cr complexes
(given in brackets) in 3-day cultures of: (1) P. angusta (0.5 mM), (2) P. and intermediates inside cells, detoxification pathways as
pastoris (0.5 mM), (3) H. polymorpha (1 mM) grown after inoculation with
well as bioconversion into biologically available forms.
approximately 0.03 mg cells/ml.
Strains having unusual characteristics such as hypersensi-
tivity, hyperaccumulation, elevated tolerance or low perme-
[22], yeast growth phase and biomass initial density [13,32] ability towards Cr compounds could be selected and
as well as on the presence of certain modulators such as ions subjected to detailed studies.
(e.g. sulfate, phosphate, ferrous), chelators, riboflavin, etc. Regarding possible environmental applications, it should
([33,34], and Fedorovych et al., unpublished). be pointed out that both Cr(III) and Cr(VI) forms are
All the yeasts employed in this study were wild-type identified in industrial effluents and waste and that both
strains previously isolated from natural sources. This work valences of the metal can be detrimental to living cells
was focused on the living yeast biomass only in order to provided they reach intracellular regions. The main finding
reveal physiological conditions affecting the bioaccumula- of this work is that yeast cells, under certain conditions, can
tion process. That is why the concentration of Cr supple- accumulate Cr(III) with an efficiency comparable to Cr(VI)
mented to the culture cultivation media was based on a 40– (cf. Fig. 5). This observation indicates either the existence of
60% growth inhibition criterion. Such sub-lethal Cr levels independent transport mechanism(s), as was considered by
had no effect on cell survival but rather induced a stress Raspor et al. [13], or, at the very least, the permeability of the
response as observed by a prolonged lag growth phase and cell membrane to trivalent chromium species. Although
the hampering of the yeasts’ proliferation potential (not Cr(III) was found to be relatively less harmful to yeast,
shown). In this respect the dark, grained structures found which is in agreement with other studies [13,22,29], its toxic
inside cells as seen in electron microscopy photographs (Fig. effect was still apparent at higher concentrations. If these
4) are the stabilised final products of chromium metabolism observations are true for other eukaryotes, there would be a
by viable yeast. However, in order to explain the detailed strong environmental demand to remove Cr(III) contami-
nature of the metal complexes and to describe the intracel- nants, too, since these species could not be regarded as ‘‘less
lular chromium distribution, further studies, involving toxic’’ or not-accumulated. So far, the general strategy for Cr
microspeciation analyses, are required. Based on the micro- (and other heavy metal) pollution control has relied upon
scopic images, it is possible that the deposition target of the dissimilatory metal reduction [10,37,38], that is the uptake
bioremediated Cr species are cellular organelles, preferen- of toxic and permeable Cr(VI) species by microorganisms
tially vacuole, rather than cell walls and plasma membranes. and plants and then subsequent bioremediation and conver-
The latter cellular structures seem not to change their sion into less toxic trivalent forms. This work may thus
contrast when the yeast is exposed to either Cr(III) or Cr(VI). imply that the environmental risk caused by Cr(III) con-
Still, Nevertheless the contribution of physical biosorption tamination is at least underevaluated.
mechanisms to the total uptake of chromium might be Finally, the study shows that yeasts are a very hetero-
significant and should not be neglected [13,35]. geneous group in terms of chromium tolerance and accu-
The chromium sensitivity thresholds and accumulation mulation. It appears that they have evolved a variety of
levels determined for Cr(III) did not correlate with those of mechanisms for metal uptake and metabolism. For that
Cr(VI) for the distributions of strains examined (Table 1 and reason, the research which would involve laboratory trans-
Figs. 2 and 3). The majority of the strains (total n = 51) were port-defective mutants as well as mutants tolerant or sensi-
sensitive to a concentration of 1–2 mM Cr(III) (n = 24) and tive to Cr is of high scientific interest in terms of helping to
0.3 mM Cr(VI) (n = 22). In the case of Cr(III) the total elucidate the mechanisms of uptake. Such mutants are being
number of strains revealed a Gaussian-like distribution over subjected to separate studies and the results will be pub-
the cellular Cr content, i.e. most of the strains tended to lished in future papers. The complexity of bioremediation
accumulate Cr within the middle-range of 0.5–3.0 mg/g d.w. processes in yeast is still a challenging problem with respect
(n = 34) (Fig. 2). However, in the case of Cr(VI) the majority to environmental pollution control and nutritional practice.
8. 1572 H. Ksheminska et al. / Process Biochemistry 40 (2005) 1565–1572
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