Isolation and characterization of triacylglycerol-secreting mutant strain from yeast,Saccharomyces cerevisiae

To establish the molecular bases for development of a microbiological system approaching excretive fermentation of useful lipids, a mutant strain that accumulates lipids in the medium was isolated from the laboratory yeast Saccharomyces cerevisiae. Following the mutagenesis to strain YP1, a long chain fatty acid utilizer with ethylmethane sulfonate, the mutant strain, STG1, was selected from about 80,000 colonies. The analysis of extracellular lipids and the monitoring of leakage of intracellular proteins indicated that strain STG1 secreted lipids containing triacylglycerols into the extracellular space without cell lysis. Genetic studies clarified that this mutation was recessive and was complemented by wild-type genomic DNA fragments. STG1 was considered to be a good tool for elucidation of the molecular mechanism for transmembrane lipid transport.