Candida lipolytica mutants defective in an acyl-CoA synthetase

Abstract

Mutant strains of Candida lipolytica NRRL Y-6795, which are defective in ‘fatty acyl-CoA synthetase I’ linking to the system incorporating the fatty acyl moiety into cellular lipids (Kamiryo, et al., 1977), were cultivated on various carbon sources including odd-chain n-alkanes (C11 to C17) and their fatty acid compositions were examined. In the case of the wild-type strain grown on odd-chain n-alkanes (from C13 to C17), the proportions of odd-chain cellular fatty acids to total cellular fatty acids were markedly high, reaching 98–99% in the n-pentadecane- and n-heptadecane-grown cells. Those of the mutant strains, however, were drastically low, being at most 12–13% even in the n-heptadecane-grown cells. The total fatty acid contents in the mutant cells were 4–5% in dry weight, being slightly lower than those of the wild strain (4–7% in dry weight). The growth rates of the mutants on glucose, n-undecane and n-tridecane were comparable to those of the wild strain. When n-pentadecane, n-heptadecane, or oleic acid was used as carbon source, the mutants had lower, but still practicable, growth rates. The results obtained indicate that these mutant strains of Candida lipolytica will be useful as sources of biomass with low content of nonnatural odd-chain fatty acids.