摘要：There was a decrease in viable yeast counts depending on the duration of incubation when Candida utilis was grown in medium at pH 4.0. At pH 5.0 and 6.0, the greatest amounts of viable yeast cells were observed with the overall best growth of 4.1x108 occurring at pH 5.0 after 72 h incubation. The total viable cells of Candida tropicalis grown in media at different pH show that at pH 4.0, 5.0 and 6.0 were the greatest amounts of viable yeast cells. At these pH, the growth of Candida tropicalis was not highly influenced by the incubation time. In contrast, adjusting the initial pH to 7.0 and 8.0 produced low yeast cell yields. At pH 9.0, growth occurred to a much lesser extent than at the other pH values. The best pH for maximum biomass production by Candida utilis was 5.0 while maximum amount of lipid was produced at 9.0. There was a net decrease in the total lipids associated with increases in the yeast biomass. Maximum lipid amount, produced by Candida tropicalis,is 59.4 (mg/L) and this was obtained at pH 9.0. The maximum biomass concentration of 8.1 (g/L) was obtained at pH 6.0. Changes in the fatty acid composition of Candida utilis at different initial media pHs show that at most pH values, the C16:0, C18:1, C18:2 fatty acids predominated. The fatty acid profiles of Candida tropicalis at different initial medium pH show that linoleic acid (С18:2) was the predominant fatty acid at most pH values.
