Abstract
From out of 76 types of culture strains, wax-ester-accumulating microorganisms were screened using oleic acid as the sole carbon source.
Acinetobacter calcoaceticus IAM 12088 was found to be microorganism accumulating the most wax. It produced 4.9g/L of wax esters from 30g/L of oleic acid. These wax esters consisted mainly of the fatty acid and alcohol having C18 : 1, C16 : 1 and C14 : 1, units. C16 : 1 and C14 : 1 fatty acids may possibly have formed from oleic acid by β-oxidation. After reduction of the C18 : 1, C16 : 1 and C14 : 1 fatty acids to the corresponding fatty alcohols, ester formation between fatty acids and fatty alcohols took place. Wax esters were also produced from triglycerides such as palm and mink oil as sole carbon sources.
The mutant having decreased capacity to degrade wax esters was isolated by NTG from the selected strains. The mutant accumulated wax esters in amounts exceeding 3 times that of parental strain, the yield being 9.7g/L and conversion rate, 48.5% from 20g/L of oleic acid. Supplementation of oleic acid and corn steep liquor during cultivation gave the best yield of 30.5 g/L. The maximum conversion rate of oleic acid to wax esters was 53.5%.
