Fukui Youhei, Yoshida Mitsuhiro, Shozen Kei-ichi, Funatsu Yasuhiro, Takano Takashi, Oikawa Hiroshi, Yano Yutaka, Satomi Masataka
National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama 236-8648, Japan.
J Gen Appl Microbiol. 2012;58(4):273-81. doi: 10.2323/jgam.58.273.
In fish sauce production, microorganisms are associated with the fermentation process; however, the sequential changes in the bacterial communities have never been examined throughout the period of fermentation. In this study, we determined the bacterial floras in a fish sauce mash over 8 months, using three different culture media and 16S rRNA gene clone library analysis. During the first 4 weeks, viable counts of non-halophilic and halophilic bacteria decreased and were dominated by Staphylococcus species. Between 4 and 6 weeks, halophilic and highly halophilic bacterial counts markedly increased from 10(7) to 10(8) cfu/g, and the predominant species changed to Tetragenococcus halophilus. The occurrence of T. halophilus was associated with an increase of lactic acid and a reduction of pH values. In contrast, non-halophilic bacterial counts decreased to 10(6) cfu/g by 6 weeks with Bacillus subtilis as the dominant isolate. Clone library analysis revealed that the dominant bacterial group also changed from Staphylococcus spp. to T. halophilus, and the changes were consistent with those of the floras of halophilic and highly halophilic isolates. This is the first report describing a combination approach of culture and clone library methods for the analysis of bacterial communities in fish sauce mash.
在鱼露生产过程中，微生物与发酵过程相关；然而，在整个发酵期间，细菌群落的连续变化从未被研究过。在本研究中，我们使用三种不同的培养基和16S rRNA基因克隆文库分析方法，对鱼露酱醪8个月内的细菌菌群进行了测定。在最初的4周内，非嗜盐菌和嗜盐菌的活菌数下降，且以葡萄球菌属为主。在4至6周期间，嗜盐菌和高度嗜盐菌的数量从10(7) cfu/g显著增加到10(8) cfu/g，优势菌种变为嗜盐四联球菌。嗜盐四联球菌的出现与乳酸增加和pH值降低有关。相比之下，到6周时，非嗜盐菌数量降至10(6) cfu/g，以枯草芽孢杆菌为优势分离株。克隆文库分析表明，优势细菌类群也从葡萄球菌属变为嗜盐四联球菌，这些变化与嗜盐菌和高度嗜盐菌分离株菌群的变化一致。这是第一份描述采用培养和克隆文库方法相结合来分析鱼露酱醪中细菌群落的报告。
