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, Nost oc, Cylindrospermum, Calothrix, Microchaete, Rivularia, Aulosira, Toly pothrix 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 utiliza tion varied from species to species and also depended on the growth co nditions. None of the species tested grew photo- or chemoheterotrophic ally at a comparable rate to that of their respective autotrophic grow th rate. Thirteen species were found to be obligate autotrophs. Ten sp ecies showed appreciable photoheterotrophic and chemoheterotrophic gro wth in presence of glucose, fructose or sucrose in the medium.