Methods for Yeast Lipid Extraction

Bose Institute, 93/1 Acharya Prafulla Chandra Road, Calcutta-700 009

Manuscript received 16 May 1978, revised 2 January 1979, accepted 27 April 1979

The efficiencies of different methods of lipid extraction from a fat yeast, \(Lipomyces\) \(starkeyi \) and a non-fat yeast, \(Saccharomyces\) \(cerevisiae\) were compared. The methods include extraction of cells, (i) directly and (ii) after disruption of cells with HCI, lytic enzymes and mechanical grinding in presence of solvents. Regarding lipid yield, extrac­tion methods involving cell disruption by HCI, lytic enzyme glusulase and mechanical grinding were found to be about equally efficient but more effective than other methods involving direct solvent extraction of intact cells. The residues left after solvent extrac­tion of disrupted cells (except in the case of HCI treatment) were found to contain some lipid (ca. 10%) which can be extracted by HCI treatment followed by solvent extraction. The composition of lipid extracted from these two yeasts and from a \(Rhodotorula\) \(glutinis\) Y₃ strain, another fat yeast, by mechanical grinding and HCI treatment were evaluated. The results revealed that HCI treatment of cells followed by solvent extrac­tion is the most simple and efficient method for fat yeasts like L. starkeyi and R. glutinis Y₃ where triglyceride is the major lipid component and sterol ester is a minor one. Phospholipids of L. \(starkeyi \) and R. \(glutinis\) Y₃ were less degraded by HCI treatment than by mechanical grinding. On the other hand, in non-fat yeast, S. \(cerevisiae\) where sterol ester and phospholipids are the major lipid components, HCI treatment degrades phospholipid to a larger extent than mechanical grinding. It appears that the lipid components are compartmentalised in cells of the fat yeasts in a different way than in the non-fat yeast.