Growth-inhibition of hiochi bacteria in namazake (raw sake) by bacteriocins from lactic acid bacteria.
The bacteriocins produced by Lactococcus lactis subsp. lactis C101910 (C101910) and NBRC 12007 (NBRC 12007) were used to prevent the growth of sake spoiling hiochi bacteria (Lactobacillus hilgardii, Lactobacillus fructivorans, and Lactobacillus paracasei) in namazake, which is raw (unpasteurized) sake. The bacteriocin concentrations required for decreasing the viable cell concentrations of L. hilgardii and L. fructivorans below the detection limit (1.0 x 10(2) cells/ml) in 24 h from the initial concentration of 4.0-9.5 x 10(5) cells/ml in the namazake at pH 4.5 and at 4 degrees C, were 18-35 U/ml and 5.6 U/ml for the bacteriocin from C101910 and NBRC 12007, respectively. To decrease the viable cell concentration of L. paracasei from the initial concentration of 7.5 x 10(5) cells/ml to below the detection limit (1.0 x 10(2) cells/ml) in 24 h, 350 U/ml bacteriocin from C101910 and 140 U/ml bacteriocin from NBRC 12007 were required. In experiments using McIlvaine buffer (pH 4.5) with 15% ethanol instead of namazake as the medium, the viable cell concentrations of L. hilgardii and L. paracasei decreased to less than 1.0 x 10(2) cells/ml, whereas those of L. fructivorans decreased to less than 1.0 x 10(3) cells/ml, when bacteriocins were added at the concentrations that had proven effective in namazake. The membrane depolarization assay using a fluorescent probe showed that the presence of ethanol stimulated the collapse of the membrane potential induced by bacteriocins. The ethanol induced collapse of the membrane potential suggests that the application of bacteriocins at the storage stage of namazake is more beneficial than when used in other stages of the sake brewing process.
Taniguchi
Masayuki
M
Department of Materials Science and Technology, Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan. mtanig@eng.niigata-u.ac.jp
Ishiyama
Yohei
Y
Takata
Takeomi
T
Nakanishi
Toshihiro
T
Kaneoke
Mitsuoki
M
Watanabe
Ken-ichi
K
Yanagida
Fujitoshi
F
Chen
Yi-sheng
YS
Kouya
Tomoaki
T
Tanaka
Takaaki
T
D000434:Alcoholic Beverages / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001430:Bacteriocins / Q000378:metabolism / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology; D007778:Lactobacillus / Q000187:drug effects* / Q000254:growth & development; D013294:Lactococcus lactis / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D000431:Ethanol