2012 Volume 29 Pages 1-6
We measured all of the d-amino acids in 37 samples taken in 3 kinds of sake brewing processes (Kimoto, Kimoto adding starter latctic acid bacteria, and Sokujomoto) and 4 samples of sake rice using high-performance liquid chromatography. We found that d-Asp, d-Glu, d-Ala, and d-Val were produced in all three sake brewing proceses, but d-His, d-Arg, and d-Pro were detected only in Kimoto. d-Ile and d-Phe were detected only in Kimoto adding starter lactic acid bacteria. d-Leu was detected in Kimoto adding starter latctic acid bacteria and Sokujomoto but not in Kimoto. Most of these d-amino acid concentrations increased from Fukuremae to Modosi period. The d-amino acid concentrations observed were different in each brewing process, and the highest amount of d-Asp (32.1 μM), d-Glu (25.3 μM), and d-Ala (160.8 μM) were contained in Kimoto at Jousou period. In contrast, sake rice contained d-Asp, d-Ala, d-Val, d-Glu, and d-Ser, but all of their concentrations were under 1 μM. Lactic acid bacteria type culture strains (Lacobacillus sakei NBRC 15893 and Leuconostoc mesenteroides NBRC 102480) isolated from Kimoto produced d-amino acids (for L. sakei: d-Ala, d-Glu, and d-Asp; for L. mesenteroides: d-Ala, d-Glu, and d-Lys). We found that all of the gene products of the amino acid racemase homologue genes from L. sakei and L. mesenteroides showed alanine, glutamate, aspartate, lysine, or histidine racemase activity. Accordingly, Kimoto is one of effective methods to increase d-amino acid contents in sake. The D-amino acids in sake were produced by lactic acid bacteria in Kimoto, and the amino acid racemases of the lactic acid bacteria probably catalyze the synthesis of various d-amino acids in the organisms.
