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S-Adenosylmethionine (SAM) is an important metabolite that participates in many reactions as a methyl group donor in all organisms, and has attracted much interest in clinical research because of its potential to improve many diseases, such as depression, liver disease, and osteoarthritis. Because of these potential applications, a more efficient means is needed to produce SAM. Accordingly, we developed a positive selection method to isolate SAM-accumulating yeast in this study. In Saccharomyces cerevisiae, one of the main reactions consuming SAM is thought to be the methylation reaction in the biosynthesis of ergosterol that is catalyzed by Erg6p. Mutants with deficiencies in ergosterol biosynthesis may accumulate SAM as a result of the reduction of SAM consumption in ergosterol biosynthesis. We have applied this method to isolate SAM-accumulating yeasts with nystatin, which has been used to select mutants with deficiencies in ergosterol biosynthesis. SAM-accumulating mutants from S. cerevisiae K-9 and X2180-1A were efficiently isolated through this method. These mutants accumulated 1.7-5.5 times more SAM than their parental strains. NMR and GC-MS analyses suggested that two mutants from K-9 have a mutation in the erg4 gene, and erg4 disruptants from laboratory strains also accumulated more SAM than their parental strains. These results indicate that mutants having mutations in the genes for enzymes that act downstream of Erg6p in ergosterol biosynthesis are effective in accumulating SAM.

An extracellular lipase produced by the glycolipidproducing yeast Kurtzmanomyces sp. I-11 was puriˆed by ammonium sulfate precipitation and column chromatographies on DEAE-Sephadex A-25, SP-Sephadex C-50, and Sephadex G-100. Based on the analysis of the puriˆed lipase on sodium dodecyl sulfatepolyacrylamide gel electrophoresis, the puriˆed lipase was judged to be homogeneous and its molecular mass was estimated to be approximately 49 kDa. The optimum temperature for the activity was 759 C, and the activity was very stable at temperatures below 709 C. The active pH range of this lipase was 1.9-7.2, and the activity was stable at pH below 7.1. The lipase showed a preference for C18 acyl groups by measurements with pnitrophenyl esters and triglycerides as substrates. The lipase was very stable in the presence of various organic solvents at a concentration of 40z. Although the Nterminal sequence of the Kurtzmanomyces lipase was very similar to that of lipase A from Candida antarctica, the pH proˆles of the two lipases were signiˆcantly diŠerent.

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Brewer's and baker's yeasts appear to have components that protect from liver injury. Whether sake yeast, Saccharomyces cerevisiae Kyokai no. 9, also has a hepatoprotective effect has not been examined. Here we show that sake yeast suppresses acute alcoholic liver injury in mice. Male C57BL/6 mice that had been fed a diet containing 1% sake yeast for two weeks received three doses of ethanol (5 g/kg BW). In the mice fed sake yeast, ethanol-induced increases in triglyceride (TG) and glutamate pyruvate transaminase (GPT) were significantly attenuated and hepatic steatosis was improved. In addition, sake yeast-fed mice showed a smaller decrease in hepatic S-adenosylmethionine (SAM) level and a smaller increase in plasma homocysteine (Hcy) level after ethanol treatment than the control mice, suggesting that a disorder of methonine metabolism in the liver caused by ethanol was relieved by sake yeast. These results indicate that sake yeast protects against alcoholic liver injury through maintenance of methionine metabolism in the liver.Key words: Saccharomyces cerevisiae; sake yeast; liver injury; alcohol; methionine metabolismThe physiological effects of brewer's yeast and its components in mammals have been well studied. For example, brewer's yeast cell wall reduces serum lipid levels in rats, 1) and improves defecation by contributing to the fermentation ability, water holding capacity, and swelling force of the large intestine.2) To understand the gene expression of Saccharomyces bayanuis as a lager brewer's yeast during beer fermentation, sequencing of the whole genome was performed.3) This provided further information about the physiological effects of brewer's yeast as well as the brewing of beer.On the other hand, there have been few studies of the physiological effects of sake yeast, Saccharomyces cerevisiae Kyokai yeast, which is used in sake (Japanese rice wine) brewing. Manabe et al. reported that both sake yeast and sake lees, the leftovers of sake brewing, increase spontaneous locomotive activity in rats. 4) They proposed that the effect of sake lees partly depends on sake yeast. The sake lees contain rice components that are not assimilated by sake yeast and sake koji, Aspergillus oryzae, components of sake yeast and sake koji, and their metabolites. Therefore, to understand the physiological effects of sake yeast may help to understand the physiological effcts of sake lees and to find new uses for them.A distinctive characteristic of sake yeast is that it is able to accumulate higher levels of S-adenosylmethionine (SAM) intracellularly than other yeasts, bacteria, molds, and some other microorganisms.5,6) SAM functions as a major methyl group donor in transmethylation of proteins, nucleic acids, polysaccharides, phospholipids, and fatty acids and as a precursor of glutathione. It has been proposed as a chemotherapeutic agent for alcoholic liver disease, 7) depression, 8) osteoarthritis , 9) and Alzheimer's disease. 10) Another distinctive characteristic of sake yeast is that it has a higher ethanol t...