Polar lipids of brewer's yeasts

Both traditional and DNA-based methods sometimes fail to differentiate between closely related strains of commercial interest in the brewing industry. The aim of this study was to compare species and sub species of Saccharomyces cerevisiae on the basis of their polar lipid chemistry using Chromatographic methods. Six isolates were studied after propagation under batch conditions. Polar lipids were then extracted from lyophilised cultures and analysed by TLC in order to separate phospholipid families. TLC showed that the major phospholipid classes present were PC > PE > PG. Two unidentified phospholipids were found, one only in strain 34/70. The major peaks detected by GLC were identified as methyl esters of palmitic acid and palmitoleic acid. The fatty acid composition of PC varied between strains and novel data on lecithin acyl constituents were observed. The polar lipid method succeeded in differentiating strain 34/70 - one of the most commonly used brewer's lager yeast - from strain 34/78 and other species tested. The presence of unusual polar lipids in Saccharomyces sensu stricto yeasts may be useful in distinguishing between other closely related strains. © 2005 The Institute of Brewing & Distilling.