Taxonomic implication of sterol composition in the genusChlorella

Thirty-five isolates of the genusChlorella were grown under standardized conditions and analyzed for sterol composition. Six different sterol synthetic patterns were found. Two patterns were characterized by nuclear unsaturation at C-5 and one type by nuclear unsaturation at C-7. The remaining isolates all synthesize sterols with a diunsaturated nucleus (C-5+C-7) with various modifications. Subtype 1 synthesizes only C₂₈ sterols, subtype 2 produces C₂₈ and C₂₉ sterols, and subtype 3 (1 isolate) produces C₂₈ sterols with nuclear unsaturation at C-5+C-8 in addition to the Δ^5,7 C₂₈ sterols seen in the first 2 subtypes. Comparison of the sterol composition of strains shared in common with taxonomic researchers showed good correlation with the taxonomic scheme of Fott and Novakova which has been confirmed by Kessler and coworkers using other biochemical markers. Scientific article no. A-3030, contribution no. 6093 of the Maryland Agricultural Experiment Station.