The Accumulation of Carbohydrate in Chlorella vulgaris under Heterotrophic Conditions

Abstract

The accumulation of carbohydrate in two strains of Chlorella vulgaris under autotrophic and heterotrophic conditions has been examined. Cells of the Emerson strain, which cannot divide in the dark on a glucose medium, accumulate much more carbohydrate under heterotrophic conditions than they do when growing autotrophically. Much of the extra carbohydrate is in the form of polysaccharide, particularly starch. The extent of this accumulation is not related to the size of the cells. In the Brannon no. 1strain, where there is no light requirement for cell division, there is also a marked accumulation of carbohydrate, chiefly of some polysaccharide other than starch. The relation between the carbohydrate accumulation and the contrasting behaviour of the two strains under fully heterotrophic conditions is discussed.