P-23
Phospholipid profiling of Saccharomyces carlsbergensis isolates using electrospray ionization mass spectrometry
Presenter: Wolfgang Tosch, The University of Manchester, Faculty of Life Sciences, Manchester, UK
Co-Authors: David B. Drucker, and Geoff D. Robson, The University of Manchester, Faculty of Life Sciences, Manchester, UK; and Valerie Boote, The University of Manchester, School of Chemistry, Manchester, UK

Saccharomyces carlsbergensis strain 34/70 is well known to be the most-used strain for lager beer production. The difference between this strain and very closely related strain 34/78 is the former's less-flocculating character. This single physiological trait can cause technical difficulties in beer production. The aim of this study was to establish a combination of thin-layer chromatography (TLC) with electrospray ionization mass spectrometry (ESI-MS) as a strain-typing technique. Both strains (34/70 and 34/78) were harvested after continuous culture under standard conditions. Polar lipids were then extracted from lyophilized cultures and analyzed by TLC in order to separate phospholipid families. Individual phospholipid classes were extracted and investigated using ESI-MS, to gain further information on individual molecular species. TLC analysis detected phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylglycerol (PG), cardiolipin (CL), phosphatidylserine (PS), phosphatidylinositol (PI), and phosphatidic acid (PA). ESI-MS of the PE band observed from TLC showed that electrospray mass spectra were highly reproducible for repeat cultures. Novel findings were that both brewing strains displayed major phospholipid peaks with m/z: 714, PE (34:2); 742, PE (36:2); 758, PE (37:1). However, strain 34/78 had additional peaks of m/z: 700, PE (33:2) and 728 (35:2). Stain 34/70 had an extra peak with m/z: 686 PE (32:2). We conclude that combined TLC/ESI-MS can be a useful chemotaxonomic technique for differentiation of closely related yeast strains. This novel approach will aid quality assurance. Methodology could be suitable for yeast collections and larger industrial companies.

Wolfgang Tosch holds a degree in brewing science (Diplom-Braumeister) from the Technische Universität München, Center of Life Science Weihenstephan, Germany. In 2003, he earned a masters degree (M.Phil.) in microbiology, School of Biological Sciences, the University of Manchester, Manchester, UK. Currently, he is researching on a Ph.D. program at the Faculty of Life Sciences of the University of Manchester.