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Productivity
of the microalga Chlorella kessleri in outdoor open thin-layer batch
cultures |
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Archiv
fur Hydrobiologie. Supplementband. Algological studies. Stuttgart
[Arch. Hydrobiol. (Suppl.) (Algol. Stud.)], vol. 132, pp. 103-121,
2000 QH301 .A77 |
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Chlorella
kessleri was grown in batch mode in nutrient saturated cultures;
nutrients were replenished daily. Mean productivities of the
alga during bath growth cycles in three outdoor open
thin-layer cultivation units (224 m super(2) each), were evaluated
by means of a simple mathematical model. Measured data comprised:
daily solar energy input per 1 m super(2) of growth area, culture
temperature and dry matter content (d.m.) of alga in
the culture. Productivity P sub(24) per day [g (d.m.)/m
super(2)24/h] was expressed in the model as PL (productivity during
the light period) and a loss term for night respiration. The
mean relative discrepancy between measured and calculates P sub(24)
values was 9.4% for the total number of 25 evaluated batch growth
cycles from the two cultivation seasons. The model may be used for
prediction of algal productivity under other climatic
conditions for the culture system and algal strain employed.
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Night
biomass loss and changes in biochemical composition of cells during
light/dark cyclic culture of Chlorella pyrenoidosa.
Journal
of Fermentation & Bioengineering. 82(6). 1996. 558-564. NOT AT
OSU
The
effects of culture conditions on biomass loss during the dark
period (night biomass loss) and the biochemical composition of
Chlorella pyrenoidosa cells cultured under a repeated light/dark
cycle were investigated. During the night, decreases were observed
in the biomass concentration and carbohydrate contents of the cells while
their protein content increased. These changes imply that in the absence
of light energy, intracellularly stored carbohydrate is metabolized as an
energy source. This energy is used in part for cell maintenance and in
part for protein synthesis. The changes were maximum during the
exponential growth phase, decreased with the age of the culture,
and were affected by the culture conditions during both the day and
night. The night biomass loss decreased with increasing
temperature during the day, but was greater in cultures
grown under high light intensity. At any given growth phase, the
night biomass loss increased with increasing cell carbohydrate
content. The culture conditions during the day affected the
night biomass loss through their influence on the cell biochemical
composition. Although biomass loss could be reduced by lowering the
temperature and avoiding mixing of the culture during the
night, the loss could not be completely prevented. Since Chlorella
cells can grow heterotrophically on some organic carbon sources during the
dark period, a cyclic light-autotrophic/dark-heterotrophic culture
was investigated as a means of preventing night biomass loss. By
adding glucose to the culture during the night, continuous
cell growth during both day and night was achieved without adverse
effect on the biochemical composition of the cells. Similar results were
obtained using ethanol or acetate as an alternative organic carbon source.
These latter compounds are preferred to glucose as organic carbon sources
in order to reduce the risk of contamination.
TEMPERATURE
AS AN IMPORTANT FACTOR AFFECTING PRODUCTIVITY AND NIGHT BIOMASS
LOSS IN SPIRULINA-PLATENSIS GROWN OUTDOORS IN TUBULAR PHOTOBIOREACTORS.
Bioresource
Technology 38 (2-3). 1991. 95-100. TD930 .A391
Outdoor
experiments using tubular photobioreactors have shown that in summer the
average net productivity of a Spirulina platensis culture grown at
the optimal temperature of 35.degree.C was superior by 23% to that
observed in another culture grown at 25.degree.C. The rates of
night biomass loss were higher in the culture grown at
25.degree.C (average 7.6% of dry weight) than in the one grown at
35.degree.C (average 5% of dry weight). We found that the night
biomass loss was dependent on the temperature and light irradiance
at which the cells were grown, since these factors influence the biomass
composition. A net increase in carbohydrate synthesis was observed when
the cells were grown under high light irradiance or at the suboptimal
temperature of 25.degree.C. The excess of carbohydrate synthesized
during the day was only partially utilized for night protein
synthesis.
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Productivity
of the alga Scenedesmus obliquus in thin-layer outdoor
cultures: Verification of a mathematical model |
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Archiv
fur Hydrobiologie. Supplementband. Algological studies. Stuttgart
[Arch. Hydrobiol. (Suppl.) (Algol. Stud.)], vol. 119, pp. 135-145,
1997 QH301 .A77 |
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The
alga had been grown semicontinuously in the two 50 m super(2)
culture units in which suspension of alga recirculated on a
slanted growth surface (slope 3 %) equipped with baffles. At
night, algal culture had been stored in aerated tanks.
Culture layer thickness on the growth surface was 4-5 cm,
concentration of alga 1-2 g/l (dry matter). Experimental data
of the mean productivity of alga in the light phase PL and on
a 24 h basis P sub(2)4 obtained in 16 decades in the growth season
May-October and the corresponding culture parameters were used for
verification of mathematical model. The sensitivity analysis
revealed that PL was influenced mainly by culture temperature
and light energy absorbed in the light period. PL was independent of
the concentration of alga, that can be expected as a result
of virtually complete absorption of light in dense algal
suspension. An unstructured deterministic model in which irradiance,
culture temperature and the length of light period were
included, was applied to the PL experimental data. Productivity P
sub(2)4 of alga was expressed in the model by means of PL and
a term for algal respiration in the dark phase. The mean
relative error between experimental and calculated from the model
algal productivities was about 20 %.
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Productivity,
respiration and chemical composition of the green alga
Scenedesmus incrassatulus grown in outdoor cultivation units with
and without baffles
Archiv
fuer Hydrobiologie, Supplement [ARCH. HYDROBIOL. (SUPPL.)], vol.
106, pp. 111-128, 1995 |
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In
this paper the performance of the two outdoor open cultivation units
225 m super(2) of culture area each, installed at the production
base Rupite (Bulgaria), was compared in short-term experiments
during four years (1986-1990). The cultivation units were 30 m long
and the inclination of the cultivation surface was 3 %. During the
light period, the algal cultures were flowing down the
inclined surfaces, over night, the algal cultures were
kept in aerated reservoirs. One cultivation unit was equipped by
transverse baffles forming a culture layer of 40-50 mm thick (thick
layer). The second cultivation unit was used without baffles and the
culture layer thickness was 7 mm (thin layer). The average
algal dry matter in thick layer was 1.6 plus or minus 0.4 g/l
(areal density 71.8 plus or minus 19.9 g dry matter per m super(2)).
In thin layer culture the average values of these parameters were:
conc. of algae 5.7 plus or minus 1.6 g/l; areal density 39.8
plus or minus 11.4 g/m super(2). Algal productivity
(determined for light period of cultivation) was independent of
areal density greater than 30 g/m super(2) and it was linearly
correlated to the irradiance of the culture surface. The average
productivities [g dry matter/m super(2)/day] were - thick layer: P =
24.8 plus or minus 6.7; thin layer P = 27.2 plus or minus 8.6.
Night losses of biomass [% of dry matter] were - thick layer:
11.9 plus or minus 10.0; thin layer: 12.7 plus or minus 8.6.
Specific rate of algae respiration [mg O sub(2)/g
algae/h] in the light period was correlated against the
absolute culture temperature by ARRHENIUS equation with the
activation energy of respiration E = 19.375 kJ/mol. Chemical
composition of the fresh algae was practically the same in
the control (thick layer) and experimental (thin layer) cultivation
units. |
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Growth
physiology of a marine nitrogen-fixing cyanobacterium
(Nodularia harveyana) in outdoor culture |
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Journal
of Applied Phycology [J. APPL. PHYCOL.], vol. 6, no. 5-6, pp.
533-537, 1994 |
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The
performance of Nodularia harveyana, a N sub(2)-fixing
cyanobacterium isolated from seawater, has been studied
outdoors in two different culture systems: open pond (OP) and
tubular photobioreactor (TPR). The productivity in both devices was
influenced by areal density. The maximum yield obtained was 12.0 g
(d.wt)m super(-2)/day in OP and 14.0 g (d.wt)m super(-2)/day in TPR
in August, corresponding to the highest solar radiation received. In
a month-long experiment with the cyanobacterium cultivated in
TPR at high circulation speed, a net increase in productivity was
obtained over that at low circulation speed. The influence of
temperature on the productivity of the cultures grown
in open ponds and tubular photobioreactors has been investigated.
The higher productivity obtained in TPR compared to OP was
attributed to its better controlled temperature conditions.
In outdoor culture the maximum nitrogenase activity did not
coincide with the maximum light intensity, but occurred in early
afternoon. The amount of carbohydrate accumulated during the day
probably influenced the rate of dark nitrogenase activity and its
duration in the night. |
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Effect
of temperature on yield and night biomass loss in
Spirulina platensis grown outdoors in tubular photobioreactors.
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Journal
of Applied Phycology [J. APPL. PHYCOL.], vol. 3, no. 2, pp. 103-109,
1991 QK564
.J681 |
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Outdoor
experiments carried out in Florence, Italy (latitude 43.8 degree N,
longitude 11.3 degree E), using tubular photobioreactors have shown
that in summer the average net productivity of a Spirulina platensis
culture grown at the optimal temperature of 35 degree C was
superior by 23% to that observed in a culture grown at 25 degree C.
The rates of night biomass loss were higher in the culture
grown at 25 degree C (average 7.6% of total dry weight) than in the
one grown at 35 degree C (average 5%). Night biomass loss
depended on the temperature and light irradiance at which the
cultures were grown, since these factors influenced the biomass
composition. A net increase in carbohydrate synthesis occurred when
the culture was grown at a low biomass concentration under high
light irradiance or at the suboptimal temperature of 25
degree C. Excess carbohydrate synthesized during the day was only
partially utilized for night protein synthesis.
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FLUXES
BETWEEN TROPHIC LEVELS AND THROUGH THE WATER-SEDIMENT INTERFACE.,
1990, pp. 221-226, Hydrobiologia, vol. 207 QH90 .H9
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Four
algae of freshwater phytoplankton were studied in
monospecific culture: Chlorella vulgaris, Fragilaria
crotonensis, Staurastrum pingue and Synechocystis minima.
Experiments were performed to determine the growth rate over a wide
range of light intensities (5-800 mu E m super(-2)/s, 15/9
light/dark photoperiod) and temperatures (10-35 degree
C). The results provide a set of parameters (particularly the
maximal growth rate associated to optimal conditions of light and
temperature) for a three-equation model used to described the
growth rate response of a non-nutrient-limited culture.
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Survival
of Scenedesmus acuminatus (Chlorophyceae) in darkness.
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Journal
of Phycology [J. PHYCOL.], vol. 25, no. 3, pp. 509-515, 1989
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Survival
of the green alga Scenedesmus acuminatus Lagerh. in complete
darkness was studied in axenic batch cultures at 7
degree C and 22 degree C for three months. The decrease in cell
numbers was insensitive to temperature and slower than the
loss of dry weight. However, the lag phase before cells began to
lyse was more than twice as long at 7 degree C than at 22 degree C.
The decline in cellular carbohydrates and proteins occurred in two
phases. During the first 3-4 days, the decrease in cellular
carbohydrate levels was significantly accelerated and
temperature-sensitive. Pyrenoids disappeared within 5 days of
darkness. Proteins showed 20-fold higher degradation rates at
22 degree C than at 7 degree C during the first 4 days. Thereafter,
the rates of carbohydrate and protein decomposition were slow and
temperature-independent. By contrast, lipids degraded only
little at virtually constant and temperature-insensitive
rates over the entire experimental period.
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Jensen
B, Cox R. 1983. Effect of oxygen concentration on dark nitrogen fixation
and respiration in cyanobacteria. Arch Microbiol 135:287-292. QR1
.A7 COMPACT
Padan
E, Raboy B, Shilo M. 1971. Endogenous dark respiration of the blue-green
alga, Plectonema boryanum. J Bacteriol 106(1):45-50. QR1 .J6
COMPACT
Shyam
R, Raghavendra A, Sane P. 1993. Role of Dark Respiration in
Photoinhibition of Photosynthesis and Its Reactivation in the
Cyanobacterium Anacystis nidulans. Physiol Plant 88(3):446-452. QK1
.P55
Gibson
C. 1985. Growth rate, maintenance energy and pigmentation of planktonic
cyanophyta during 1-hour light:dark cycles. Br Phycol J 20(2):155-162.
QK564 .B7
Richardson
L, Castenholz R, Wilson K. 1987. Enhanced survival of the cyanobacterium
Oscillatoria terebriformis in darkness under anaerobic conditions. Appl
Environ Microbiol 53:2151-2158. QR1 .A6
Sentsova
O, Nikitina K, Gusev M. 1975. Characteristics of oxygen metabolism in the
obligate phototrophic blue-green alga Anabaena variabilis in darkness.
Mikrobiologiia 44(2):283-8. QR1 .M5 COMPACT
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