RESUMO
When either aerobic or anaerobic cultures of Saccharomyces cerevisiae were supplemented with aspartic and fatty acids in place of biotin, stationary phase populations were very small compared with those obtained in the presence of biotin. Similarly, these acids failed to fulfil the role of biotin-requiring strain of Aspergillus nidulans. Furthermore, a requirement for saturated fatty acid was found with anaerobically cultured S. cerevisiae. Cells were fragmented when biotin was replaced by aspartic and oleic acids alone, while cellular integrity was maintained, but with only slight growth, when biotin was replaced by oleic and palmitic acids together with aspartate. The importance of biotin in the growth of A. nidulans was particularly pronounced in the presence of glucose. In a medium containing glucose, growth ceased when biotin was replaced by aspartate and Tween 80 (a source of saturated and unsaturated fatty acids), but such replacement permitted a very small amount of growth to occur in the absence of glucose.