HETEROTROPHIC GROWTH OF SEVERAL FILAMENTOUS BLUE-GREEN-ALGAE

We have screened forty one species of filamentous, heterocystous blue-green algae of local rice-fields belonging to the genus Anabaena, Nostoc, Cylindrospermum, Calothrix, Microchaete, Rivularia, Aulosira, Tolypothrix and Westiellopsis for their ability to grow in presence of the organic substrates glucose, fructose and sucrose in light in presence or absence of DCMU (3'-(3-4-dichlorophenyl) 1',1'-dimethyl urea) and in the dark. Substrate specificity and efficiency of substrate utilization varied from species to species and also depended on the growth conditions. None of the species tested grew photo- or chemoheterotrophically at a comparable rate to that of their respective autotrophic growth rate. Thirteen species were found to be obligate autotrophs. Ten species showed appreciable photoheterotrophic and chemoheterotrophic growth in presence of glucose, fructose or sucrose in the medium.