Japanese sake making using wild yeasts isolated from natural environments.

Saccharomyces cerevisiae is one of the most important microorganisms for the food industry, including Japanese sake, beer, wine, bread, and other products. For sake making, Kyokai sake yeast strains are considered one of the best sake yeast strains because these strains possess fermentation properties that are suitable for the quality of sake required. In recent years, the momentum for the development of unique sake, which is distinct from conventional sake, has grown, and there is now a demand to develop unique sake yeasts that have different sake making properties than Kyokai sake yeast strains. In this minireview, we focus on "wild yeasts," which inhabit natural environments, and introduce basic research on the wild yeasts for sake making, such as their genetic and sake fermentation aspects. Finally, we also discuss the molecular breeding of wild yeast strains for sake fermentation and the possibility for sake making using wild yeasts.

Association of suppression of extracellular signal-regulated kinase phosphorylation by epigallocatechin gallate with the reduction of matrix metalloproteinase activities in human fibrosarcoma HT1080 cells.

Matrix metalloproteinases (MMPs) play a crucial role in the process of cancer invasion and metastasis. Previous findings suggested that epigallocatechin gallate (EGCG), a main flavanol of green tea, caused decreased levels of MMP-2 and MMP-9 activities to be secreted into culture medium. To obtain further information on EGCG-mediated regulation of these MMPs, the effects of EGCG on enzyme activity, mRNA expression, and mitogen-activated protein kinase (MAPK) activities in human fibrosarcoma HT1080 cells were examined. EGCG was confirmed to suppress the gelatin-degrading activities due to MMP-2 and MMP-9 in the culture medium. This suppression of enzyme activities by EGCG was consistent with the decreased levels of MMP-2 and MMP-9 mRNAs. EGCG-mediated suppression was also observed for MT1-MMP mRNA. EGCG-mediated suppression of the level of MMP-9 transcript was correlated with its suppression of MMP-9 promoter activity. EGCG inhibited the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), which are the members of an MAPK family necessary for MMP-9 up-regulation. EGCG also suppressed p38 MAPK activity but gave no effects on stress-activated protein kinase/c-Jun N-terminal kinase activity. These findings suggest that suppression of ERK phosphorylation by EGCG is involved in the inhibition of expression for MMP-2 and MMP-9 mRNAs, leading to the reduction of their enzyme activities of the cancer cells. Methyl derivatives, epigallocatechin-3-O-(3-O-methyl) gallate and epigallocatechin-3-O-(4-O-methyl) gallate, exhibited effects similar to, but weaker than, those of EGCG, suggesting the important role of an unsubstituted triphenolic ester structure in these activities.

Purification and characterization of an extracellular beta-agarase from Bacillus sp. MK03.

A new beta-agarase was purified from an agarolytic bacterium, Bacillus sp. MK03. The enzyme was purified 129-fold from the culture supernatant by ammonium sulfate precipitation, anion exchange and gel filtration column chromatographic methods. The purified enzyme appeared as a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Estimation of the molecular mass by SDS-PAGE and gel filtration gave values of 92 kDa and 113 kDa, respectively. The N-terminal amino acid sequence of the enzyme showed no homology to those of other known agarases. The optimum pH and temperature for this enzyme were 7.6 and 40 degrees C, respectively. The predominant hydrolysis product of agarose by this enzyme was neoagarotetraose, indicating the cleavage of beta-1,4 linkage. This enzyme could hydrolyze neoagarohexaose to produce neoagarotetraose and neoagarobiose; it could not hydrolyze these products. The enzyme digested agarose by endo-type hydrolysis.

Purification and characterization of an extracellular alpha-neoagarooligosaccharide hydrolase from Bacillus sp. MK03.

An agarolytic bacterium was isolated from soil in Gifu prefecture, Japan, and identified as Bacillus sp. strain MK03. The strain secreted neoagarooligosaccharide hydroluse into the culture medium. The enzyme was purified 49.7-fold from the culture fluid by ammonium sulfate precipitation and anion-exchange and gel-filtration column chromatographic methods. The purified enzyme appeared as a single band on polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS)-PAGE. Estimations of the molecular mass by gel filtration and SDS-PAGE gave values of 320 kDa and 42 kDa, respectively, indicating that the enzyme is octametric. The enzyme cleaved the alpha-1,3 linkage in neoagarobiose to produce 3,6-anhydro-L-galactose and D-galactose. It also selectively cleaved the alpha-1,3 linkage at the nonreducing end in neoagarotetraose or neoagarohexaose to give 3,6-anhydro-L-galactose and agarotriose or agaropentaose. The optimum temperature and pH for the enzyme were 30 degrees C and 6.1, respectively. The N-terminal amino acid sequence showed no homology to sequences of other known neoagarooligosaccharide hydrolases and agarases.