Catalytic Decomposition of the Oleaginous Yeast Cutaneotrichosporon Oleaginosus and Subsequent Biocatalytic Conversion of Liberated Free Fatty Acids

A single step catalytic cell wall lysis and triglyceride hydrolysis combined with the enzymatic conversion of lipids using the oleaginous yeast Cutaneotrichosporon oleaginosus (ATCC 20509) as a model is described. Catalytic decomposition of yeast cells resulted in hydrolysis of about a third of cellular polysaccharides and all triglycerides. Enzymatic processing of the lipid fraction with an oleate hydratase from Stenotrophomonas maltophilia led to conversion of oleic acid to 10-hydroxystearic acid (10-HSA) (50%) without additional purification. Cell wall polysaccharides were depolymerized by in situ formed amino acids from cell protein fragments. The activity of the in situ generated, free amino acids was higher compared to that of additionally added acids. Studies with the cellobiose and β-(1→3)-glucan indicated that glutamic and aspartic acids, which are the dominant amino acids in yeast cells, are surprisingly more effective in hydrolysis in aqueous phase than sulfuric acid. This points to a concerted mechanism of glycosidic ether bond cleavage catalyzed by amino acids rather than to a pathway catalyzed by hydronium ions. The overall yield of the presented downstream process at 453 K resulted in the release of 80% of total lipids.