Lipid Composition of Sheffersomyces stipitis M12 Strain Grown on Glycerol as a Carbon Source
1Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
2Department of Food Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
3Karlovac University of Applied Science, Trg Josipa Jurja Strossmayera 9, 47000 Karlovac, Croatia
4Department of Medical Chemistry, Biochemistry and Clinical Chemistry, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000 Rijeka, Croatia
Received: 14 October 2019
Accepted: 29 June 2020
lipid composition, Sheffersomyces stipitis, S-adenosyl-L-methionine production, lipid metabolism scheme
Research background. In this study the content and composition of lipids in ergosterol-reduced Sheffersomyces stipitis M12 strain grown on glycerol as a carbon source is determined. Blocking the ergosterol synthesis route in yeast cells is a recently proposed method for increasing S-adenosyl-L-methionine (SAM) production.
Experimental approach. The batch cultivation of M12 yeast was carried out under aerobic conditions in a laboratory bioreactor with glycerol as carbon source, and with pulsed addition of methionine. Glycerol and SAM content were monitored by high-performance liquid chromatography, while fatty acid composition of different lipid classes, separated by solid phase extraction, was determined by gas chromatography.
Results and conclusion. Despite the reduced amount of ergosterol in yeast cells, thanks to the reorganized lipid metabolism, M12 strain achieved high biomass yield and SAM production. Neutral lipids prevailed (making more than 75 % of total lipids), but their content and composition differed significantly in the two tested types of yeast. Unsaturated and C18 fatty acids prevailed in both the M12 strain and wild type. In all fractions except free fatty acids, the index of unsaturation in M12 strain was lower than in the wild strain. Our tested strain adjusts itself by changing the content of lipids (mainly phospholipids, sterols and sterol esters), and with desaturation adjustments, to maintain proper functioning and fulfil increased energy needs.
Novelty and scientific contribution. Reorganization of S. stipitis lipid composition caused by blocking the metabolic pathway of ergosterol synthesis was presented. A simple scheme of actual lipid metabolism during active SAM production in S. stipitis, grown on glycerol was constructed and shown. This fundamental knowledge of lipid metabolic pathways will be a helpful tool in improving S. stipitis as an expression host and a model organism, opening new perspectives for its applied research.
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