The study evaluated the growth of Chlorella vulgaris microalgae under different conditions over two phases. In phase one, C. vulgaris was grown with the addition of sugars but failed to thrive and was overtaken by bacteria. In phase two under increased light intensity, C. vulgaris concentration and absorbance increased steadily but specific growth rates remained low. Higher light intensity showed potential to improve microalgae biomass but further research is needed to maximize output.
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Effects of LED light spectra on active oxygen metabolism and expression of an...Agriculture Journal IJOEAR
Abstract— The effects of various LEDs on active oxygen metabolism and patterns of SOD, POD and CAT isozymes in Houttuynia cordata Thunb. seedlings were investigated. After three weeks of light treatment, the MDA content was higher under blue LED compared with the control (P﹤0.05), while it decreased under white, red and yellow LEDs (P﹤0.05). The content of H2O2 was gradually increased in red, yellow, green and blue LEDs. The production rate of superoxide anion increased under yellow and blue LEDs by contrast with the control (P﹤0.05), and it decreased under white LED (P﹤0.05). LEDs altered the banding patterns of POD enzymes where the more loci of POD isozymes were observed under green and blue LEDs. The increased intensities of Fe-SOD were showed in green and blue LEDs. As for Mn-SOD and CAT enzymes, enhanced intensities appeared in all LED groups compared with the control. Our results indicated that the antioxidant system of Houttuynia cordata seedlings were more sensitive to short light wavelength than the long ones.
Low Cost Anaerobic Treatment of Municipal Solid Waste Leachateiosrjce
IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) multidisciplinary peer-reviewed Journal with reputable academics and experts as board member. IOSR-JESTFT is designed for the prompt publication of peer-reviewed articles in all areas of subject. The journal articles will be accessed freely online
Dissertation ppt biostimulation- a potential practice for wastewater treaat...Sumer Pankaj
Phycoremediation is a green technology that supports the direct use of living green microalgae for in situ, or in place removal, degradation, of contaminants in soils, sludge, sediments, surface water and ground waters by the mechanisms of bio-transformation, bio-accumulation, bio-concentration, bio-sparging.
It can be said by the current study that microalgae has a great potential for the treatment of industrial and municipal wastewaters as compared to the chemical treatments available commercially. Biological systems are much more efficient in cleaning the excess nutrients from the waste water followed by generation of valuable biomass which can be applied in the food, fertilizer, energy production as use of inorganic chemicals like lime and ferrous sulphate generates huge amount of sludge in textile industries, but on the other hand static anaerobic treatment using acclimatized MLSS gives better colour reduction with zero sludge generation. Microalgal cells can be used in free form to treat waste waters containing high C.O.D., high ammonical nitrogen and high TDS. It not only provides a better reduction of chemicals from wastewaters but it also helps to reduce the operational cost of ETP. Microalgaes not only helps to remediate industrial waste waters but also to treat sweage water and to restore natural water bodies like lakes and ponds. As they are active in remediating the chemicals but also it shows an antagonistic effect against some pathogenic germs like total coliforms and fecal coliforms.
These microalgal cells can also be combined with bacterial biomass of activated sludge process to develop an Algal-Bacterial consortium (ALBA) for better enhancement in the reduction of chemicals from the wastewaters as this symbiotic relation of algae and bacteria provides high satiability of the microalgae along with MLSS and faceable in terms of price and economy for instance the bacterial biomass provides carbon dioxide to algal cells for photosynthesis and in return the bacteria acquires oxygen from algae. The harvested biomass from the ETP’s can be used as bio-fertilizers as it consists of appropriate ratio of vital macro and micro nutrients like N,P,K etc. which enhance the growth of plantlets. It can also be used as aqua feeds for shrimps, fishes and molluscs. Furthermore these microlgal cells are non-toxic in the environment as it becomes a part of food chain and do not cause eutrophication. Therefore, micro-algal based treatment is most suitable for the treating the waste waters and restoring the natural water bodies as compared to other chemical treatments.
Influence of diets on detoxifying enzymatic activities of insectsSAURABHPADAMSHALI
Process of detoxification in insects is mediated by certain enzymes. Insects use enzymes associated with labial salivary glands or guts to detoxify plant defensive compounds or suppress plant induced defenses. Ex.- Esterases, mixed function oxidases, glutathione s-transferases
May 2015 c. vulgaris to biofuel presentationJoseph Barnes
Chlorella vulgaris is a species of green microalgae capable of generating lipids suitable for conversion into biofuel via the process of transesterification. Viable production of biofuel from green microalgae requires high biomass densities, 1.0 g/L or more. We attempted to enhance cell concentrations and biomass densities of Chlorella vulgaris by growing the microalgae in a fed-batch system. A practical fed-batch system using indoor photobioreactors was designed and modified during the course of the project; commercial-grade plant fertilizers were used for the principle substrates. Additional mineral nutrients, including MgSO4, were also used in order to boost growth rates and the carrying capacity for the closed bioreactors. During the course of the experiment we implemented three different methods. The fed-batch system successfully enhanced the targeted parameters of biomass yield and cell concentration. We reached a maximum biomass density of 0.58 g/L, this was short of our goal but higher than our earlier results in previous projects. We also analyzed the effects of distinctive wavelengths of visible light (colored light versus white light) on cell concentrations. Red light (wavelength of 650 nm) led to the most positive growth, producing a value twice more than that generated using only green light (540 nm). A final variable which we briefly touched was the surface area to volume ratio of the photobioreactor.
PowerPoint Presentation for Microalgae Undergraduate Research Project at UPRA...Joseph Barnes
This is the PowerPoint presentation I prepared for my research project which is attempting to enhance the growth of microalgae for purposes of generated biofuel. This presentation covers my undergraduate research project at the UPRA during the fall semester of 2014 under the department of physics and chemistry. The phase in the research covered by this presentation involves attempting to grow C. vulgaris, a green microalgae, to the density of 1 gram per liter or more by supplementing the growth media with carbon dioxide gas. Unfortunately, although we failed to reach our mark of 1 g/L, we did learn how mixing carbon dioxide gas with aeration is better than directly injecting the gas into the growth media. Also, we were able to improve the biomass density compared to our earlier attempts.
Effects of LED light spectra on active oxygen metabolism and expression of an...Agriculture Journal IJOEAR
Abstract— The effects of various LEDs on active oxygen metabolism and patterns of SOD, POD and CAT isozymes in Houttuynia cordata Thunb. seedlings were investigated. After three weeks of light treatment, the MDA content was higher under blue LED compared with the control (P﹤0.05), while it decreased under white, red and yellow LEDs (P﹤0.05). The content of H2O2 was gradually increased in red, yellow, green and blue LEDs. The production rate of superoxide anion increased under yellow and blue LEDs by contrast with the control (P﹤0.05), and it decreased under white LED (P﹤0.05). LEDs altered the banding patterns of POD enzymes where the more loci of POD isozymes were observed under green and blue LEDs. The increased intensities of Fe-SOD were showed in green and blue LEDs. As for Mn-SOD and CAT enzymes, enhanced intensities appeared in all LED groups compared with the control. Our results indicated that the antioxidant system of Houttuynia cordata seedlings were more sensitive to short light wavelength than the long ones.
Low Cost Anaerobic Treatment of Municipal Solid Waste Leachateiosrjce
IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) multidisciplinary peer-reviewed Journal with reputable academics and experts as board member. IOSR-JESTFT is designed for the prompt publication of peer-reviewed articles in all areas of subject. The journal articles will be accessed freely online
Dissertation ppt biostimulation- a potential practice for wastewater treaat...Sumer Pankaj
Phycoremediation is a green technology that supports the direct use of living green microalgae for in situ, or in place removal, degradation, of contaminants in soils, sludge, sediments, surface water and ground waters by the mechanisms of bio-transformation, bio-accumulation, bio-concentration, bio-sparging.
It can be said by the current study that microalgae has a great potential for the treatment of industrial and municipal wastewaters as compared to the chemical treatments available commercially. Biological systems are much more efficient in cleaning the excess nutrients from the waste water followed by generation of valuable biomass which can be applied in the food, fertilizer, energy production as use of inorganic chemicals like lime and ferrous sulphate generates huge amount of sludge in textile industries, but on the other hand static anaerobic treatment using acclimatized MLSS gives better colour reduction with zero sludge generation. Microalgal cells can be used in free form to treat waste waters containing high C.O.D., high ammonical nitrogen and high TDS. It not only provides a better reduction of chemicals from wastewaters but it also helps to reduce the operational cost of ETP. Microalgaes not only helps to remediate industrial waste waters but also to treat sweage water and to restore natural water bodies like lakes and ponds. As they are active in remediating the chemicals but also it shows an antagonistic effect against some pathogenic germs like total coliforms and fecal coliforms.
These microalgal cells can also be combined with bacterial biomass of activated sludge process to develop an Algal-Bacterial consortium (ALBA) for better enhancement in the reduction of chemicals from the wastewaters as this symbiotic relation of algae and bacteria provides high satiability of the microalgae along with MLSS and faceable in terms of price and economy for instance the bacterial biomass provides carbon dioxide to algal cells for photosynthesis and in return the bacteria acquires oxygen from algae. The harvested biomass from the ETP’s can be used as bio-fertilizers as it consists of appropriate ratio of vital macro and micro nutrients like N,P,K etc. which enhance the growth of plantlets. It can also be used as aqua feeds for shrimps, fishes and molluscs. Furthermore these microlgal cells are non-toxic in the environment as it becomes a part of food chain and do not cause eutrophication. Therefore, micro-algal based treatment is most suitable for the treating the waste waters and restoring the natural water bodies as compared to other chemical treatments.
Influence of diets on detoxifying enzymatic activities of insectsSAURABHPADAMSHALI
Process of detoxification in insects is mediated by certain enzymes. Insects use enzymes associated with labial salivary glands or guts to detoxify plant defensive compounds or suppress plant induced defenses. Ex.- Esterases, mixed function oxidases, glutathione s-transferases
May 2015 c. vulgaris to biofuel presentationJoseph Barnes
Chlorella vulgaris is a species of green microalgae capable of generating lipids suitable for conversion into biofuel via the process of transesterification. Viable production of biofuel from green microalgae requires high biomass densities, 1.0 g/L or more. We attempted to enhance cell concentrations and biomass densities of Chlorella vulgaris by growing the microalgae in a fed-batch system. A practical fed-batch system using indoor photobioreactors was designed and modified during the course of the project; commercial-grade plant fertilizers were used for the principle substrates. Additional mineral nutrients, including MgSO4, were also used in order to boost growth rates and the carrying capacity for the closed bioreactors. During the course of the experiment we implemented three different methods. The fed-batch system successfully enhanced the targeted parameters of biomass yield and cell concentration. We reached a maximum biomass density of 0.58 g/L, this was short of our goal but higher than our earlier results in previous projects. We also analyzed the effects of distinctive wavelengths of visible light (colored light versus white light) on cell concentrations. Red light (wavelength of 650 nm) led to the most positive growth, producing a value twice more than that generated using only green light (540 nm). A final variable which we briefly touched was the surface area to volume ratio of the photobioreactor.
PowerPoint Presentation for Microalgae Undergraduate Research Project at UPRA...Joseph Barnes
This is the PowerPoint presentation I prepared for my research project which is attempting to enhance the growth of microalgae for purposes of generated biofuel. This presentation covers my undergraduate research project at the UPRA during the fall semester of 2014 under the department of physics and chemistry. The phase in the research covered by this presentation involves attempting to grow C. vulgaris, a green microalgae, to the density of 1 gram per liter or more by supplementing the growth media with carbon dioxide gas. Unfortunately, although we failed to reach our mark of 1 g/L, we did learn how mixing carbon dioxide gas with aeration is better than directly injecting the gas into the growth media. Also, we were able to improve the biomass density compared to our earlier attempts.
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Metabolomics Analysis on Antifungal Activities Produced by Penicillium oxalic...Agriculture Journal IJOEAR
—In-vitro antagonist tests such as disc diffusion and minimum inhibition concentration (MIC) were conducted against C. gloeosporioides. 1 H-NMR coupled with multivariate statistical analysis was carried out to identify possible compounds produced. Glucose crude extract exhibited the highest percent inhibition of radial growth (PIRG) with 75% and the lowest MIC value with 78 µg mL-1. For metabolomics, different metabolites produced were clustered according to the carbon sources used and gave a representative impression of the metabolites produced by P. oxalicum T3.3. The study has shown the potential of using a combination of 1 H-NMR spectroscopy and multivariate statistical analysis and their correlation with MIC in differentiating the effect of carbon sources used based on the identification of possible metabolites contributing to their differences. Findings from this work may potentially provide the basis for further studies on both antimicrobial activities against plant pathogen and elucidation of the metabolite compounds produced by P. oxalicum T3.3.
PHOTOSYNTHESIS: What we have learned so far? Zohaib HUSSAIN
No matter how complex or advanced a machine, such as the latest cellular phone, the device cannot function without energy. Living things, similar to machines, have many complex components; they too cannot do anything without energy, which is why humans and all other organisms must “eat” in some form or another. That may be common knowledge, but how many people realize that every bite of every meal ingested depends on the process of photosynthesis?
Influence Of Different Nitrogen And Organic Carbon Sources On Microalgae Grow...iosrjce
Microalgae based biofuels are getting attention due to energy crisis and enviromental protection. In
the present study, the Chlorella sp. was cultivated in BG-11 medium at batch mode. The effect of different
nitrogen (sodium nitrate, potassium nitrate and urea) and organic carbon (glucose, glycerol and sucrose)
sources were analyzed on growth and lipid accumulation on this species. The highest biomass growth and
biomass productivity of chlorella sp. was found 1.29±0.04 g/l, 76.96±4.5mgl-1
d
-
1 in urea. However in case of
organic sources, the biomass growth and productivity was found maximum in glucose (1.43±0.075 g/l 86.04±3.2
mgl-1
d
-1
). The lipid content was examined using folch method and found better in potassium nitrate nitrogen
source (11.84%) . Among organic carbon sources, the maximum lipid content (13.22% and lipid yield 189.94
mg/l were found in case of glucose, followed by glycerol and sucrose. Various properties of biodiesel obtained
from chlorella sp. such as Cetane number, Saponification value, Iodine value and Degree of unsaturation were
followed standerds set by the national petroleum agency (ANP255), ASTMD6751 and EN14214.
CULTIVATION OF OSCILLATORIA SP IN DAIRY WASTE WATER IN TWO STAGE PHOTO BIOREA...civej
This paper presents an integrated approach to cultivate microalgae in dairy wastewater and to
investigate the capability of the organism for biodiesel production. The present study was carried out
using tolerant strains of microalgae collected from dairy effluent treatment plant, Kochi. Selected blue
green algal strains were mass cultured in the laboratory and acclimatized using different concentrations
of synthetic effluent. Blue green algal filaments were immobilized inside the primary and secondary
photobioreactors. The experiment was conducted in two stages including batch and continuous
treatment. The stage 1 of the experiment was designed for the reduction of physical impurities and the
nutrients. Stage 2 was designed mainly for the cultivation of blue green algae in dairy waste water by
utilizing the extra nutrients . Reduction of 94 -99.5% in phosphate was observed after 48 h of treatment
in the primary and secondary photobioreactors. The level of phosphate, total hardness, ammoniacal
nitrogen in the MSE was reduced by 97%,93 %, 81% respectively. BOD was reduced to 370mg L-1 from
1500 mg L-1 after 48 hrs of treatment in the primary reactor. COD was reduced to 85 mg L -1 from an
initial value of 1500 mg L -1 from medium strength effluent (MSE) and 90-95 % removal of COD was
also obtained from high strength effluent(HSE) during the study period. Biomass developed within the
reactor was harvested at every 15 days intervals from the secondary reactor and analyzed for lipids and
fattyacids. Presence of C14:0, C16:0,C18:0, C18:1 and C18:2 fatty acids strongly supports its abilility for
biodiesel production.
www.ijera.com 1|P a g e Production of microbial enzymes by new method of cult...IJERA Editor
We have developed efficient methods for long-term culturing and selection of highly active versions of the original cultures of micromycetes – producers of enzymes. We theoretically substantiated and experimentally confirmed an advantage of growing micromycetes in a new filament-spongy immobilized growth structure on the substrate relative to the traditional method of deep cultivation of free cells in the form of pellets. When comparing a traditional with our innovative method of cultivation, many advantages of the latter are revealed, above all being the possibility of the formation of new highly selective cultures in the long process of their growth with modified culturally - morphological properties.
Similar to Summer microalgae report, Sept 2014 (20)
www.ijera.com 1|P a g e Production of microbial enzymes by new method of cult...
Summer microalgae report, Sept 2014
1. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Observed Growth Rate of Chlorella Vulgaris under
Mixotrophic Conditions –
Observed Growth Rate of C.v. under Hight Light Intensity in
Autotrophic Conditions
Undergraduate Investigation
QUIM 4999
Commenced: July 8, 2014
Ended: August 22, 2014
Student: Joseph A. Barnes (440-13-0709)
Laboratory Supervisor: Dr. Hirohito Torres
University of Puerto Rico at Arecibo
Abstract
Green microalgae can serve as a source for biodiesel production, providing a means of
generating renewable energy, which is eco-friendly and comparatively simple to manage.
This experimental study has been partitioned into two phases. The first phase of this
study was to evaluate the effects of subjecting Chlorella vulgaris, a species of green
microalgae, to mixotrophic conditions. Three groups, each in duplicate, were observed
over a period of eight days in order to analyze the effects of feeding C. vulgaris simple
and complex sugars (heterotrophic conditions). The autotrophic effects were satisfied by
a steady light-source regulated to a 12:12 hour light-dark cycle. The experimental study
was evaluated on the basis of observed changes in cell-concentration and light
absorbance. Initial findings demonstrated a failure of the algae to successfully thrive
under heterotrophic effects (sugar supplementation plus aeration). The second phase of
this study was to evaluate the outcomes of subjecting the remaining batches of C.
vulgaris to a highly intensified light source, with wavelengths of blue and red, optimal for
photosynthetic activity. Initial findings revealed a positive correlation between cell
concentration and light intensity, although without a substantial gain in cell biomass.
1
2. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Introduction
The topic of microalgae has been
gaining considerable attention in recent
years, due to its capacity of serving as a
source of renewable energy and as a
means of finding economical
independence from costly oil
importation. Green microalgae,
including the species of Chlorella
vulgaris, the principal specimen of this
experimental study, is capable of
autotrophic growth, absorbing sunlight
and carbon dioxide in order to produce
sugars for the purpose of sustaining and
reproducing itself. Once collected and
dried, fatty acids and triglycerides can be
extracted from the algae, subjected to the
process of transesterification, and
converted into biodiesel.
This method of producing
biodiesel possesses clear advantages
over other implemented techniques. First,
green microalgae can be grown
relatively quickly in shallow bodies of
water or in photobioreactors, without the
use of the excessive square-miles of
surface terrain as in the case of other oil-
producing crops (e.g. coconut trees, corn,
soybeans, etc.) (Hirohito, 2013;
Scarsella et al., 2010). In other words, a
good crop of green microalgae can
generate a much higher quantity of
biodiesel per square-mile of land than
any other oil crop. Second, green
microalgae absorb vast quantities of
carbon-dioxide. Producing large masses
of microalgae means sequestering even
larger amounts of carbon-dioxide from
the atmosphere, which signifies that
growing microalgae can be a carbon-
neutral process, that is, the carbon
dioxide emitted by the burning of
biodiesel is reabsorbed by the
microalgae. This cycle may inhibit any
long-term accumulation of carbon-
dioxide in the upper atmosphere from
the combustion of biodiesel. In fact, so
potential is the algae’s property of
sequestering carbon-dioxide, that it is the
subject of research as a potential means
of reducing overall carbon-dioxide
emissions in the environment (Sahoo et
al., 2012). A third advantage of
microalgae is its ability to utilize
heterotrophic metabolism in order to
absorb sugars and other organic-carbon
substances (Debjani et al., 2012; Xiaoyu
et al., 2014; Leesing and Kookkhuntod,
2011; Scarsella et al., 2010). This makes
a two-fold benefit. For one, by being
able to grow and reproduce under
heterotrophic conditions, the farming of
microalgae will not be inextricably
linked to the environment. Some
measures can be taken to maintain high
microalgae production in the absence of
sufficient sunlight and environmental
carbon dioxide. And for the other,
microalgae can prove a viable means for
removing industrial waste and unwanted
byproducts, which substances would
serve as the principal sources of organic
carbon for the algae (Debjani et al.,
2012; Xiaoyu et al., 2014).
The study was divided into two
phases, wherein the first was focused on
observing the effects of growing
Chlorella vulgaris under mixotrophic
conditions as opposed to just autotrophic.
In order to satisfy these mixotrophic
conditions, the microalgae were fed a
simple sugar (dextrose) and a mixture of
simple and complex sugars (molasses).
The autotrophic metabolism was to be
maintained by exposure to a steady
source of light regulated to a 12:12 hour
light-dark cycle. The effects were
evaluated on the basis of cell-
concentration and light absorbance. The
results were observed over a period of
eight days.
2
3. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Following the sugar
supplementation in the first phase, the
study was carried to a second phase
aimed at analyzing the effects of a stark
increase in the light intensity sustaining
the autotrophic conditions. The
parameters observed were cell
concentration and light absorbance.
Materials and Method
Phase 1
The microalgae Chlorella
vulgaris seed culture was purchased
from the UTEX culture collection in
Texas. The growth medium used in this
study consisted of a solution of distilled
water with a 0.75 g/L concentration of a
standard brand-X 20-20-20 all-purpose
fertilizer, which provided 0.15 g/L
concentrations of nitrogen, phosphoric
acid and potassium, essential nutrients
necessary for promoting and sustaining
the growth of autotrophs (table 2). Six 1-
liter flasks were prepared with 630 mL
of growth medium in each. Next, each
flask was inoculated using 70 mL of
seed culture, establishing a 9:1 ratio of
growth medium to cell volume. Two
flasks were set aside for the control
group (Control Group 1 & 2); two other
flasks were supplemented with dextrose
at a concentration of 10 g/L (Dextrose
Group 1 & 2); the final two flasks were
supplemented with molasses at a
concentration of 10.0 g/L (Molasses
Group 1 & 2) (photo a).
All six flasks were placed upon
an industrial mixer (Environ Shaker),
which was set to shake the solutions at a
speed of 125 rpm. The light source
consisted of four regular household
fluorescent light bulbs, providing an
average light intensity of 1,400 lux. The
bulbs were set on a timer which
regulated the exposure of light to a 12:12
hour light/dark cycle.
All six flasks were aerated via
two pumps with the air hoses arranged in
series, in order to supplement the media
with carbon-dioxide drawn from the
surrounding air. The average rate of
aeration was over 660 ml/minute.
Phase 2
One of the four standard
fluorescent light-bulbs was replaced with
a highly efficient LED light device that
emits high intensity light at blue and red
wavelengths. Measured light intensity
climbed to an average of 8,770 lux. The
remaining flasks from phase 1 (CG 1 &
2) were subjected to the new light
intensity.
Analysis Procedures
Changes in cell concentration
were measured directly by cell-counting
using a hemacytometer and a light-
microscope.
Light absorbance was measured
with a spectrophotometer at red
wavelengths (690 nm).
Dry biomass was measured in
triplicate using 15 mL samples from
each unit and applying centrifugation to
form pellets. The samples were diluted
and subjected to a second centrifugation
to remove salts; samples were placed in
an incubator at 80°C for 24 hours to
remove humidity.
Results and Discussion
Phase 1
As the graph provided will
demonstrate (figure 1), the dextrose and
molasses groups experienced a
stagnation coupled with a steady decline
in algae cell concentrations. After the
3
4. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
eighth day, both sugar groups were
discarded and phase 1 was terminated.
The sugars and aeration had promoted
the growth of bacteria and protozoa,
which presence was easily detectable by
the microscope as well as by
macroscopic growths (photo b). In a
short while, large concentrations of
bacteria had developed which had stifled
and significantly reduced the cell
concentration of C. vulgaris. The
absorbance tests with regards to the
sugar supplemented groups do not
correlate with the cell-concentration of
algae. The pattern evinced is irregular
due to the nature of contamination by
bacteria and other microbes (figure 2).
We can gather from our studies
that in the presence of initial high sugar
concentrations and aeration, the C.
vulgaris is quickly supplanted by
bacteria and protozoa. Other measures
need to be taken (e.g. sterilization) in
order to sustain algae growth under these
particular mixotrophic conditions.
Phase 2
The LED light was installed on
the 13th
day of the experiment, and the
effects observed until the 28th
day, a
duration of 15 days. As the graphs will
demonstrate, the initial spike in light
intensity (from 1,400 lux to 8,770 lux) is
correlated to a steep climb in cell
concentration and absorbance (figure 3
and figure 4). By the end of the phase,
the cell concentrations and absorbance
were still climbing, albeit at a lesser rate.
Increase in oxygen output was also
visibly noticeable by foaming at the
surface. The main reactor containing the
seed culture experienced certain changes
in color and other properties, for reasons
not conclusively established (photo c
and d). The change in biomass as
calculated by day 28 (table 1), although
not significant, is still perceptible and
warrants consideration. For this section,
a very rough estimate for the specific
growth rate (u) was given, using
biomass concentration calculated at day
8, as the biomass concentration at the
beginning of the exponential growth
phase (Xo). The specific growth rates for
control groups 1 and 2 were very low,
falling far short of given expectations
(less than 0.07 d^-1) (table 1). It must be
noted though, that these specific growth
rates were measured in an interval of
time which included a brief period
before the LED light was installed. We
can gather from these results that an
improvement in the autotrophic
conditions (higher light intensity in red
and blue light spectra) has positive
effects on the cell concentration and
absorbance of the C. vulgaris. However,
it remains to be seen by how much the
algae can be affected by these new
conditions (i.e. maximum output). As
shown here, there is potential in
amplifying autotrophic effects (e.g.
supplying higher light intensity and
carbon dioxide supplementation) in
order to improve microalgae biomass.
Conclusion and Recommendations
Unless we undertake measures to
sterilize the samples, such as by
autoclaving, high initial concentrations
of sugars combined with aeration will
favor bacterial and protozoan growth,
which is debilitating to the microalgae.
Steps to be considered in order to avoid
sterilization, may include using reduced
concentrations of sugar, avoiding
aeration, and fortifying the conditions
which are favorable for photosynthesis
(e.g. more light and more carbon-
dioxide). Here listed are a few
propositions to consider:
4
5. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
5
1. Growth of algae solely by
autotrophic means, with a given
high light intensity and graduated
boosts of carbon-dioxide
supplementation.
2. Growth of algae initially under
only autotrophic conditions, but
then after reaching the maximum
yield of cell-concentration,
follow with a supplementation of
sugar at a low concentration (e.g.
2 g/L).
It is certainly recommended that further
research be done to study more
accurately the effects of light intensity
on C. vulgaris. According to earlier
investigations (Cheirsilp and Salwa,
2012), high yields of biomass were
attained for Chlorella sp. at ideal light
intensities of 3000 to 5000 lux. The
intensity from sunlight on a clear day at
noontime (12:00 pm) measured up to
104,000 lux in the Arecibo area of
Puerto Rico in mid-August (19/8/2014).
However, it should be noted that very
high light intensities do not necessarily
correlate positively with biomass yields,
but in fact could actually limit cell
growth (Cheirsilp and Salwa, 2012).
6. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Figures, Tables, and Images
Figure 1
Cell Concentration versus Time (Phase 1)
0
50
100
150
200
250
300
350
400
450
1 3 5 7 9
Time (days)
Cellconcentration[10^4]
(cells/mL)
Control Group 1 Control Group 2 Dextrose Group 1
Dextrose Group 2 Molasses Group 1 Molasses Group 2
Sugar groups were discarded on day 8 due to contamination by microbes other than algae.
Figure 2
Absorbance versus Time (Phase 1)
0
0.2
0.4
0.6
0.8
1
1.2
1 3 5 7 9
Time (days)
Absorbance(A)[690nm]
Control Group 1 Control Group 2 Dextrose Group 1
Dextrose Group 2 Molasses Group 1 Molasses Group 2
Absorbance tests were made at 100% dilution (cell volume was diluted with an equal
volume of distilled water; 0.75mL cell volume + 0.75mL distilled water).
6
7. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Figure 3
Cell Concentration versus Time (Phase 2)
0
500
1000
1500
2000
2500
3000
3500
4000
13 15 17 19 21 23
Time (days)
Cellconcentration[10^4]
(cells/mL)
Control Group 1 Control Group 2
CG 2 received a higher intensity of light due to uneven distribution of LED light.
Figure 4
Absorbance versus Time (Phase 2)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
13 18 23 28
Time (days)
Absorbance(A)[690nm]
Control Group 1 Control Group 2
Absorbance tests were made at 100% dilution (cell volume was diluted with an equal
volume of distilled water; 0.75mL cell volume + 0.75mL distilled water).
7
8. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Table 1
Dry biomass per liter of media
Sample Source Day 1 Day 8 Day 28 u (days^-1)
Main Reactor 0.28 g/L - 0.20 g/L -
Control Group 1 - 0.033 g/L 0.33 g/L 0.0607 d^-1
Control Group 2 - 0.053 g/L 0.39 g/L 0.0544 d^-1
Note: specific growth rate (u) was calculated according to the Monod model, wherein, u
= ln(Xt – Xo)/t, where Xt is biomass concentration at time t and Xo is biomass
concentration at the beginning of the exponential growth phase. Biomass at day 8 will be
regarded as the value at the beginning of exponential growth phase, thus t = 20.
Table 2
Contents of 20-20-20 All Purpose Fertilizer Percent of mass
Nitrate nitrogen (NO2)
Ammoniacal nitrogen (NH3)
Water soluble organic nitrogen
Total available nitrogen
6.09%
3.85%
10.06%
20%
Available phosphoric acid (P2O5) 20%
Water soluble potassium (K2O) 20%
Note: a 0.75 g/L concentration of 20-20-20 all-purpose fertilizer would yield a
concentration of nitrogen of 0.15 g/L; phosphoric acid concentration would be at 0.15 g/L
and potassium concentration would be at 0.15 g/L.
Data Table for the Figures 1, 2, 3 and 4
Time Cell concentration [10^4] (cells/mL) – Sugar Groups
Days DG 1 DG 2 MG 1 MG 2
1
3
6
8
52.7
32.0
0
0.67
47.3
64.7
5.33
4.67
21.0
39.3
42.6
34.0
28.3
39.0
21.3
14.7
Time Cell concentration [10^4] (cell/mL) – Control Groups
Days CG 1 CG 2
1
3
6
8
10
13
16
22
24
41.3
100
250.3
297.4
330.6
513.9
2119
2606
3078
48.7
125
213
356
406.6
513.9
2244
3374
3766
8
9. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
Time Absorbance (A) at 690 nm – Sugar Groups
Days DG 1 DG 2 MG 1 MG 2
1
3
6
8
0.053
0.502
0.493
1.132
0.053
0.505
0.415
1.004
0.141
0.612
0.253
0.643
0.179
0.935
0.254
0.252
Time Absorbance (A) at 690 nm – Control Groups
Days CG 1 CG 2
1
3
6
8
10
13
16
22
24
28
0.037
0.052
0.084
0.079
0.111
0.148
0.308
0.518
0.564
0.627
0.044
0.065
0.084
0.104
0.127
0.170
0.337
0.616
0.674
0.714
Photos a, b, c, and d
(a) (b)
(c) (d)
9
10. Growing C. vulgaris in mixotrophic conditions and high light intensity; UPRA
10
References
Cheirsilp, B., Salwa, T., 2012. Enhanced growth and lipid production of microalgae
under mixotrophic culture condition: effect of light intensity, glucose
concentration and fed-batch cultivation. Bioresource Technology 110, 510-516
Debjani, M., van Leeuwen, J.H., Lamsal, B., 2012 Heterotrophic/mixotrophic cultivation
of oleaginous Chlorella vulgaris on industrial co-products. Algal Research 1, 40-
48.
Leesing, R., Kookkhunthod, S., 2011. Heterotrophic growth of Chlorella sp. kku-s2 for
lipid production using molasses as a carbon substrate. Internat. Conf. on Food
Engin. and Biotech. IPCBEE vol. 9
Sahoo, D., Elangbam, G., Devi, S.S., 2012. Using algae for carbon dioxide capture and
bio-fuel production to combat climate change. Phykos 42 (1), 32-38.
Scarsella, M., Belotti, G., De Filippis, P., Bravi, M., 2010. Study on the optimal growing
conditions of Chlorella vulgaris in bubble column photobioreactors. Paper
prepared by the Dept. of Chem. Engin. Mater. Environ., Sapienza Uni. of Roma.
Torres, H., 2013. On the growth of Chlorella vulgaris for lipid production. Poster
presentation at the University of Puerto Rico.
Xiaoyu F., Walker, T.H., Bridges W.C., Thornton, C., Gopalakrishnan, K., 2014.
Biomass and lipid production of Chlorella protothecoides under heterotrophic
cultivation on a mixed waste substrate of brewer fermentation and crude glycerol.
Bioresource Technology 166, 17-23.