Optimum Growth Parameters for Both Indoor and Outdoor Propagation of Microalgae,Chlorella Vulgaris and Isochrysis Galbana
Chlorella vulgaris and Isochrysis galbana were grown under different growth conditions both in indoor and outdoor cultures. Best culture conditions such as light intensities, photoperiods, salinities and nutrient concentrations were determined as well as the biochemical compositions. Indoor cultu...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2004
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/300/1/549608_FS_2004_11.pdf |
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| Summary: | Chlorella vulgaris and Isochrysis galbana were grown under different growth
conditions both in indoor and outdoor cultures. Best culture conditions such
as light intensities, photoperiods, salinities and nutrient concentrations were
determined as well as the biochemical compositions. Indoor cultures of C.
vulgaris and I. galbana, when continuously illuminated, grew optimally at 100
μmolm-2s-1 and 40 μmolm-2s-1, respectively. However, under 12 hour light, C.
vulgaris grew optimally at 200 μmolm-2s-1. The chlorophylla concentrations
in both algae were lower at higher light intensity and higher at lower light
intensity. Total protein and total lipid contents of both species were also
significantly higher (p<0.05) at lower light intensity. I. galbana contained more
lipid than C. vulgaris in those conditions. In contrast to protein and lipid,
carbohydrate content increased with increasing light intensity. Similar to C.
vulgaris, the lowest carbohydrate content of I. galbana was obtained at l0
μmolm-2s-1 conditions for both photoperiods. Although the protein contents of
C. vulgaris varied under different light intensity and photoperiod, the relative proportions of constituent amino acids were found to be almost similar. Total
essential amino acids under continuous illumination was significantly higher
(p<0.05) at the lowest and the highest intensities while in I. galbana, it was
significantly higher (p<0.05) only at the lowest intensity. It was surprising that
C. vulgaris contained high proportions of ω-3 highly unsaturated fatty acids at
continuous illuminations although both eicosapentaenoic acid (20:5ω-3) and
docosahexaenoic acid (22:6ω-3) were absent at 12 hours light. EPA in I.
galbana, was absent at 12 hours light, while the DHA was present in
relatively smaller quantities than in continuous light.
In indoor conditions, at full media concentration, the best salinity for C.
vulgaris was at 30 ppt and 25 ppt for I. galbana. C. vulgaris grown in full
media concentration contained more chlorophylla relative to that in half media
concentration. For I. galbana grown in full media concentration, chlorophylla
increased as salinity increased. Protein contents decreased as salinity
increase both at full and half strength media for C. vulgaris and I. galbana.
The cellular lipid contents of both algae were significantly higher (p<0.05) in
half media concentration. In full media concentration, total lipid contents in C.
vulgaris decreased at higher salinity but in I. galbana no clear trend in lipid
contents in relation to salinity observed. As salinity increased, higher
carbohydrate contents were found in C. vulgaris in full media concentration,
while in half media concentration an inverse trend was detected. I. galbana
also revealed higher proportions of total carbohydrates in half media
concentration compared to full media concentration. The amino acid profile of
both algae exhibited minor differences at different salinity and media concentrations. Most of the essential amino acid in C. vulgaris and I.
galbana were significantly higher (p<0.05) at lower salinity. In C. vulgaris, the
EPA was absent while only trace amount of DHA were detected in cells
grown under full media concentration. However in I. galbana the amount of
EPA was very high at higher salinity and in contrary the, DHA was higher at
lower salinity.
The growth performances of C. vulgaris outdoor cultures were relatively
better than I. galbana under all growth conditions studied. C. vulgaris grown
both in unsheltered and sheltered areas demonstrated rapid increased in cell
density after four days of culture with no lag phases observed. Unlike C.
vulgaris, cultures of I. galbana grown under unshaded conditions
demonstrated increase in cell numbers for 2 days but cells under sheltered
place demonstrated no increased at all. The highest specific growth rate in
C. vulgaris was in lower salinity at half media concentration while the
maximum cell density was achieved by cells in full media concentration of the
same salinity. For I. galbana cells density of half media concentration was
higher then in full media concentration. The highest total protein content of C.
vulgaris was obtained in culture under shaded conditions and generally total
lipid and carbohydrate were found to be higher in unshaded conditions.
However, it was unexplainable why less carbohydrate was found in older
cells at both conditions. I. galbana was a fast growing algae and the protein
as well as lipid contents were significantly higher (p<0.05) at sheltered
condition while no significant changes to carbohydrate content was recorded.
The carbohydrate content in C. vulgaris was higher in older cultures in full and half media concentration while at early culture age, the lipid content was
higher. In the early culture age of I. galbana, protein content was
insignificantly affected (p>0.05) by salinity and media concentration.
However, total lipid and carbohydrate were found higher at 15 ppt compared
to higher salinity in half media concentration.
In the bioeconomic study the production cost of C. vulgaris was found to be
directly influenced by labour cost. From the production forecast, it was
discovered that the high production cost was due to underutilized labour
force which can be reduced by having bigger scale production. In order to
break-even for one cycle of 100 L cultures, the minimum culture volume
should be 1,902 litres. |
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