Suzuki Daisuke, Ueki Atsuko, Amaishi Aya, Ueki Katsuji
Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata 997-8555, Japan.
J Gen Appl Microbiol. 2007 Apr;53(2):119-32. doi: 10.2323/jgam.53.119.
Two different isolation methods, the dilution colony-counting method (colony-isolation) and enrichment culture, were used to isolate sulfate-reducing bacteria (SRBs) from estuarine sediment in Japan. Lactate was used as an electron donor for colony-isolation, and lactate or propionate was used for enrichment culture. All isolates were classified into six different phylogenetic groups according to the 16S rRNA gene-based analysis. The closest relatives of the colony-isolates (12 strains) were species in the genera of Desulfobacterium, Desulfofrigus, Desulfovibrio and Desulfomicrobium. The closest known relative of the lactate-enrichment isolates was Desulfovibrio acrylicus and that of the propionate-enrichment isolates was Desulfobulbus mediterraneus. All isolates were incompletely-oxidizing SRBs. Overall patterns of utilization of electron donors and acceptors, as well as fermentative substrates, differed depending on the affiliation of the strain. Furthermore, even if several strains used the same substrate, the growth rates were often significantly different depending on the strain. It was strongly suggested that various species of SRBs could coexist in the sediment by competing for common substrates as well as taking priority in favorable or specific substrates for each species and the community of SRBs should be able to oxidize almost all major intermediates of anaerobic decomposition of organic matter such as lower fatty acids, alcohols and H2 as well as amino acids. Thus, it was indicated by the phylogenetic and physiological analyses of the isolates that the SRB community composed of diverse lineages of bacteria living in anoxic estuarine sediment should be able to play an extensive role in the carbon cycle as well as the sulfur cycle of the earth.
采用两种不同的分离方法，即稀释菌落计数法（菌落分离法）和富集培养法，从日本河口沉积物中分离硫酸盐还原菌（SRB）。乳酸用作菌落分离的电子供体，乳酸或丙酸用作富集培养的电子供体。根据基于16S rRNA基因的分析，所有分离株被分为六个不同的系统发育组。菌落分离株（12株）的最相近亲缘种是脱硫杆菌属、脱硫冷杆菌属、脱硫弧菌属和脱硫微菌属的物种。乳酸富集分离株最相近的已知亲缘种是丙烯酸脱硫弧菌，丙酸富集分离株最相近的已知亲缘种是地中海脱硫球菌。所有分离株均为不完全氧化型SRB。电子供体、受体以及发酵底物的总体利用模式因菌株所属类别而异。此外，即使几种菌株使用相同的底物，其生长速率也常常因菌株不同而有显著差异。强烈表明，各种SRB物种可通过竞争共同底物以及优先利用各自物种适宜或特定的底物而在沉积物中共存，并且SRB群落应该能够氧化几乎所有厌氧分解有机物质的主要中间产物，如下级脂肪酸、醇类、氢气以及氨基酸。因此，通过对分离株的系统发育和生理分析表明，生活在缺氧河口沉积物中的由不同细菌谱系组成的SRB群落应该能够在地球的碳循环以及硫循环中发挥广泛作用。
