Pure culture is a culture obtained from a single spore or cell. Preservation of pure cultures aims to maintain them in viable conditions for extended periods without genetic changes. Methods include short term techniques like periodic transfer to fresh media, and long term techniques like lyophilization (freeze drying), cryopreservation, and storage in mineral oil, saline, soil or silica gel. Proper preservation allows pure cultures to be stored and remain viable for many years while avoiding contamination or genetic mutation.
Preservation of industrially important microorganisms, methods of preservation, periodic transfer, storage in saline suspension, storage in sterile soil, cryopreservation
According to Lokesh, the goal of pure culture preservation is to preserve genetic stability and microbiological viability by use of several methods. Important techniques include the straightforward and inexpensive short-term storage of refrigeration at 4°C on agar slants; the long-term preservation of deep freezing at -70°C to -80°C with cryoprotectants like glycerol or DMSO, which guarantees little genetic changes over years; and the freeze-drying process, or lyophilization, in which cultures are frozen and dehydrated under a vacuum to preserve viability and stability over long periods of time. Research, clinical diagnostics, and industrial applications all depend on these techniques to guarantee the availability of clean microbial cultures when required.
Preservation of industrially important microorganisms, methods of preservation, periodic transfer, storage in saline suspension, storage in sterile soil, cryopreservation
According to Lokesh, the goal of pure culture preservation is to preserve genetic stability and microbiological viability by use of several methods. Important techniques include the straightforward and inexpensive short-term storage of refrigeration at 4°C on agar slants; the long-term preservation of deep freezing at -70°C to -80°C with cryoprotectants like glycerol or DMSO, which guarantees little genetic changes over years; and the freeze-drying process, or lyophilization, in which cultures are frozen and dehydrated under a vacuum to preserve viability and stability over long periods of time. Research, clinical diagnostics, and industrial applications all depend on these techniques to guarantee the availability of clean microbial cultures when required.
Pure culture preservation of microbes are described in detain. Different short and long term preservation are explained in detail. Methods like Agar slant cultures (Sub culturing) & Refrigeration , Mineral Oil or Liquid Paraffin Method,Saline suspension storage, Drying in Vacuum, Storage at low temperatures (Cryopreservation) and Lyophilization (Freeze drying) are included.
Mary theresa maintenace and transport of cultures [autosaved]Mary Theresa
maintenance and transport of cultures
maintenance of cultures
agar slant culture
paraffin method
storage in saline suspension
preservation in sterile soil
preservation by drying in vaccum
cryopreservation
lyophilization
transport media
This presentation explores the food value of mushrooms along with the long-term and short-term storage procedures. It also offers a detailed account of the nutrients that remain present in the edible mushrooms.
Pure Culture Technique
Culture : Act of cultivating microorganisms or the microorganisms that are cultivated.
Mixed culture : more than one microorganism
Pure culture : containing a single species of organism.
Common isolation techniques:
1. Streak plate method
2. Pour plate method
3. Spread plate method
4. Roll tube method
Originally isolated from nature, but increasingly "improved" by genetic manipulation via mutagenesis and selection or recombinant DNA technology or protoplast fusion (fungi)
Pure culture preservation of microbes are described in detain. Different short and long term preservation are explained in detail. Methods like Agar slant cultures (Sub culturing) & Refrigeration , Mineral Oil or Liquid Paraffin Method,Saline suspension storage, Drying in Vacuum, Storage at low temperatures (Cryopreservation) and Lyophilization (Freeze drying) are included.
Mary theresa maintenace and transport of cultures [autosaved]Mary Theresa
maintenance and transport of cultures
maintenance of cultures
agar slant culture
paraffin method
storage in saline suspension
preservation in sterile soil
preservation by drying in vaccum
cryopreservation
lyophilization
transport media
This presentation explores the food value of mushrooms along with the long-term and short-term storage procedures. It also offers a detailed account of the nutrients that remain present in the edible mushrooms.
Pure Culture Technique
Culture : Act of cultivating microorganisms or the microorganisms that are cultivated.
Mixed culture : more than one microorganism
Pure culture : containing a single species of organism.
Common isolation techniques:
1. Streak plate method
2. Pour plate method
3. Spread plate method
4. Roll tube method
Originally isolated from nature, but increasingly "improved" by genetic manipulation via mutagenesis and selection or recombinant DNA technology or protoplast fusion (fungi)
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
2. WHAT IS PURE CULTURE?
Pure culture is a culture obtain from a single spore/cell.
3. PRESERVATION
To maintain pure culture for extended periods in a viable conditions, without any
genetic change is referred as Preservation.
The aim of preservation is to stop the cell division at a particular stage i.e. to stop
microbial growth or at least lower the growth rate.
Due to this toxic chemicals are not accumulated and hence viability of
microorganisms is not affected.
OBJECTIVES OF PRESERVATION
To maintain isolated pure cultures for extended periods in a viable conditions.
To avoid the contamination.
To restrict genetic change (Mutation)
4. METHODS OF PRESERVATION AND MAINTENANCE OF MICROBIAL
CULTURE:
The method of preservation is mainly of two types-
SHORT TERM METHODS
LONG TERM METHODS
5. ¤ SHORT TERM METHODS
Periodic transfer to fresh media-
Culture can be maintained by periodically preparing a fresh culture from the
previous stock culture.
Many of the more common microbes remain viable for several weeks or months on a
medium like Nutrient agar.
It is an advantageous as it is a simple method and any special apparatus are not
required. However it is easy to recover the culture.
The transfer has the disadvantage of failing
to prevent changes in the characteristics of a
strain due to development of variants and mutants
and risk of contamination is also more in this
process.
6. PRESERVATION OF BACTERIA USING GLYCEROL
Bacteria can be frozen using 15% glycerol.
The glycerol is diluted to 30% and an equal amount of glycerol and culture
broth are mixed, dispensed into tubes, and then frozen at -10˚ C.
The viability of organisms varied such as Escherichia coli,
Diplococcus pneumonia etc. viable for 5 months, Haemophilus influnzae
viable
for 4 months, Neisseria meningtidis for 6 weeks and Neisseria gonorrhoeae
for 3 weeks
7. STORAGE BY DRYING METHOD
Spores of some microbes which are sensitive to freeze- drying, can be preserved
by drying from the liquid state rather than the frozen state.
Different procedures of drying methods are as follows:
Paper disc: A thick suspension of bacteria is placed on sterile discs of thick
absorbent paper, which are then dried over phosphorus pentoxide in a desiccation
under vacuum.
Gelatin disc: Drops of bacterial suspension in gelatin are placed on sterile plastic
petriplates and then dried off over P2O5 under vacuum.
L-drying: Bacteria in small ampoules are dried from the liquid state using a
vacuum pump and desiccant and a water bath to control the temperature. In this
suspension of the organisms are dried under vacuum from the liquid state without
freezing taking place.
8. Apart from the mentioned methods the organisms are also dried over Calcium
Chloride in vacuum and are stored in the refrigerator.
At such conditions the organisms survive for longer period than the air dried
cultures.
9. STORAGE BY REFRIGERATION
Culture medium can be successfully stored in refrigerators or cold rooms, when
the temperature is maintained at 4˚C.
At this temperature range the metabolic activities of microbes slows down greatly
and only small quantity of nutrients will be utilized.
This method cannot be used for a very long
time because toxic products get accumulated
which can kill the microbes.
10. ¤ LONG TERM METHODS
MINERAL OIL OR LIQUID PARAFFIN STORAGE
In this method sterile liquid paraffin is poured over the
slant culture of microbes and stored upright at room
temperature.
Where as cultures can also be maintained by covering agar slants by sterile
mineral oil which is stored at room temperature or preferably at 0-5°C.
It limit the oxygen access that reduces the microorganism’s metabolism and
growth, as well as to cell drying during preservation.
The preservation period for bacteria from the genera Azotobacter and
Mycobacterium is from 7-10 years, for Bacillus it is 8-12 years.
11. STORAGE IN SALINE SUSPENSION:
Bacterial culture is preserved in 1% salt concentration in screw caped tubes to
prevent evaporation.
The tubes are stored in room temperature.
Whenever needed the transfer is made on Agar Slant.
12. IMMERSION IN DISTILLED WATER:
Another inexpensive and low-maintenance method for storing fungal culture
is to immerse them in distilled water.
Fungi can be stored in this method at 20˚C, survived up to 2-10 years
depending upon the species.
FOR SPORULATING FUNGI:
It involves inoculating agar slants of preferred media with fungal cultures and
then incubating them at 25˚C for several weeks to induce sporulation.
Sterile distilled water(6-7 ml) is added aseptically to the culture, and the
surface of the culture is scraped gently with a pipette to produce a spore and
mycelial slurry.
This is kept in sterile glass vial at 25˚C and to retrieve a culture, 200-300µl of
the suspension is removed from the vial and placed on fresh medium.
13. STORAGE IN STERILE SOIL
It is mainly applied for the preservation of sporulating microorganisms.
Fusarium, Penicillium, Alternaria, Rhizopus etc. proved successful for store in
sterile soil.
Soil storage involves inoculation of 1ml of spore suspension into soil (autoclaved
twice) and incubating at room temperature for 5-10 days.
The initial growth period allows the fungus to use the available moisture and
gradually to become dormant.
The bottles are then stored at refrigerator.
Viability of organisms found around 70-80
years.
14. Lyophilization (Freeze–drying)
It is a vacuum sublimation technique.
Freeze drying products are hygroscopic
and must be protected from moisture during
storage.
By freezing the cells in a medium that contain
a lyoprotectant (usually sucrose) and
then pulling the water out using vacuum(sublimation), cells can be effectively
preserved.
Freezing must be very rapid, with the temperature lowered to well below 0˚C (as such -20˚C).
Lyophilized cultures are stored in the dark 4˚C in refrigerators.
Many microbes preserved by this method have remained viable and unchanged in their
characteristic more than 20 years.
It is very advantageous as only minimal storage space is required to preserve.
15. CRYOPRESERVATION
Cryopreservation (i.e. freezing in liquid nitrogen at -196˚C or in the gas phase
above the liquid nitrogen at -150˚C) helps survival of pure cultures for long
storage time.
In this method, the microorganisms of culture are rapidly frozen in liquid
nitrogen at -196˚C in the presence of stabilizing agents such as Glycerol or
Dimethyl Sulfoxide (DMSO) that prevent the cell damage due to formation of
ice crystals and promote cell survival.
By this method species can remain viable for
10-30 years without undergoing change in their
characteristics.
16. STORED IN SILICA GEL
Microbes can be stored in silica gel powder at low temperature for a period 1-
2 years.
The basic principle in this technique is quick desiccation at low temperature,
which allows the cell to remain viable for a long period of time.
Some of the species which are preserved on anhydrous silica gel are such as-
Saccharomyces cerevisiae, Aspergillus nidulans, Pseudomonas denitrificans,
Escherichia coli etc.
17. CONCLUSION:
Whichever technique is used for the preservation and maintenance of
industrially important organisms it is essential to check the quality of the
preserved organisms stocks. Each batch of newly preserved cultures should be
routinely checked to ensure their quality.
However preservation is essential as it reveals great importance in the field
of science. Preservation helps in research purposes, industry as well as in
biotechnological field.