A research involving random isolation and characterization of naturally occurring microalgae in Bangladesh was carried out for assessing their potential for biofuel feedstock and other uses. Among the isolates, one identified as a green alga Chlamydomonas noctigama and another one as blue-green alga Nostoc spongiaeforme were grown in modified Chu-10D medium. The optimization of their growth was performed following incubation of the isolates under different levels of media concentration, temperature, pH, light intensity and aeration. Both the species showed optimum growth in terms of total chlorophyll at a temperature of 25 o C. However, significant differences (at 5% level) in growth were observed for the isolates under other conditions. The optimum growth of Chlamydomonas noctigama was observed for the vitamin B1+B6, whereas there was no significant difference on growth of Nostoc spongiaeforme for any vitamin supplement. The optimum pH for the growth of Chlamydomonas noctigama and Nostoc spongiaeforme were 6.5 and 7.5, light intensity 110 µEm -2 s -1 and 70 µEm -2 s -1, and media concentration 2x and 1x of normal concentration, respectively.

Isolation and characterization of Chlorella vulgaris (green alga) and Anabaena variabilis (cyanobacterium) were made from natural and artificial water bodies of Dhaka University and Khulna, Bangladesh from March through December 2014 using modified Chu-10D medium to determine their potential as feedstock for biofuel production. Optimum growth measured as total chlorophyll and optical density under varying physical and chemical environments was determined. The optimum growth for C. vulgaris was obtained at pH 6.5 under light intensity of 110 μE m-2 s-1 and one and a half times the concentration of the Chu-10D. Compared to this, the optimum growth for A. variabilis was obtained at 7.0 pH, 90 μE m-2 s-1 light intensity and normal Chu 10D. Both organisms were grown at 25o C temperature. Aeration of medium showed a significant positive growth for both the isolates. Supplementation of medium with vitamin B1, B6, B7 and B12 would yield higher biomass of C. vulgaris as biofuel feedstock. Vitamins were not required for growing A. variabilis. Asiat. Soc. Bangladesh, Sci. 42(2): 191-200, December 2016

The growth of microalgae under optimized conditions was determined for assessing their growth rate and biomass production. In this study, the growth of both green algae (Chlamydomonas noctigama and Chlorella vulgaris) and cyanobacteria (Anabaena variabilis and Nostoc spongiaeforme) was measured as optical density. Chlamydomonas noctigama and Chlorella vulgaris showed the doubling time of 9.5 and 8.0 hours, respectively, whereas Anabaena variabilis and Nostoc spongiaeforme showed the doubling time of 14.8 and 16.6 hours, respectively. All the species exhibited the highest growth in terms of biomass at the phase in between stationary and death phases. J. Asiat. Soc. Bangladesh, Sci. 47(2): 161-171, December 2021