Elongation of C16:0 to C18:0 fatty acids in methylotrophic yeast Hansenula polymorpha CBS 1976 and fatty acid auxotrophic mutants.

Fatty acid elongation defective mutant was isolated from the ethyl methanesulfonate treated Hansenula polymorpha based on the growth ability. Using biochemical and genetic approaches, the mutant was characterized. When compared with the fatty acid phenotype of the parental strain, the differences in profile and content of fatty acids in V1 mutant were found. In this V1 mutant, polyunsaturated fatty acids, linoleic and alpha-linolenic acids, could not be detected with a corresponding increase in the content of mono-unsaturated fatty acids. The ratio of C16/C18 fatty acids revealed that the accumulation of C16 fatty acids was increased significantly. The experiments on fatty acid supplementation indicated that the mutant required C18:0 for the proper growth. The results of genetic complementation with the elongase genes of Saccharomyces cerevisiae confirmed that the lesion was occurred at least in the extension of C16:0 to C18:0 of V1. The H. polymorpha mutant obtained in this work will be used as a useful tool for unraveling the pathway of fatty acid synthesis and the role of fatty acids on biological processes.