Non-sulfate-reducing, syntrophic bacteria affiliated with Desulfotomaculum cluster I are widely distributed in methanogenic environments
Non-sulfate-reducing, syntrophic bacteria affiliated with Desulfotomaculum cluster I are widely distributed in methanogenic environments
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DOI：
10.1128/aem.72.3.2080-2091.2006
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发表时间：
2006-03-01
影响因子：
4.4
通讯作者：
Harada, H
中科院分区：
文献类型：
--
作者：
Imachi, H;Sekiguchi, Y;Harada, H
革兰氏阳性的Desultomaculum集群I的成员是硫酸盐还原细菌的传统观念最近受到了挑战，因为分离出了缺乏厌氧硫酸盐呼吸能力的新代表。例如，所描述的两个合养丙酸氧化种属的Pelotomaculum形成新的Desulfotomaculum亚簇ih。在本研究中，我们采用了一种多相的方法，使用非培养和培养技术来进一步表征低硫酸盐、产甲烷环境中亚簇ih细菌的出现、丰度和生理特性。基于16S rRNA(基因)的克隆、定量荧光原位杂交和实时聚合酶链式反应分析表明，在几乎所有被检测的样品中，亚簇ih群体构成了Desulfotomaculum簇I群落的相当大一部分。此外，还成功地建立了5株洗脱亚菌降解丙酸的共养富集菌，其中一株新菌株MGP是通过与产氢产甲烷菌共培养而分离到的。所分析的培养物，包括前面描述的Pelotomaculum种和菌株MGP，都没有消耗亚硫酸盐、硫酸盐或有机磺酸盐。根据这些表型观察，对所有浓缩/(Co)培养物的dsrAB(编码异化亚硫酸盐还原酶的α和β亚基的硫酸盐呼吸途径的关键基因)的基于PCR的筛选是阴性的，只有一个例外。令人惊讶的是，MGP菌株含有dsrAB，在硫酸盐存在和不存在的情况下转录。基于这些和以前的发现，我们假设Desulfotomaculum亚群Ih的成员最近采取了一种同养的生活方式，以便在低硫酸盐、产甲烷的环境中茁壮成长，从而失去了祖先对异化硫酸盐/亚硫酸盐还原的能力。
The classical perception of members of the gram-positive Desulfotomaculum cluster I as sulfate-reducing bacteria was recently challenged by the isolation of new representatives lacking the ability for anaerobic sulfate respiration. For example, the two described syntrophic propionate-oxidizing species of the genus Pelotomaculum form the novel Desulfotomaculum subcluster Ih. In the present study, we applied a polyphasic approach by using cultivation-independent and culturing techniques in order to further characterize the occurrence, abundance, and physiological properties of subcluster Ih bacteria in low-sulfate, methanogenic environments. 16S rRNA (gene)-based cloning, quantitative fluorescence in situ hybridization, and real-time PCR analyses showed that the subcluster Ih population composed a considerable part of the Desulfotomaculum cluster I community in almost all samples examined. Additionally, five propionate-degrading syntrophic enrichments of subeluster Ih bacteria were successfully established, from one of which the new strain MGP was isolated in coculture with a hydrogenotrophic methanogen. None of the cultures analyzed, including previously described Pelotomaculum species and strain MGP, consumed sulfite, sulfate, or organosulfonates. In accordance with these phenotypic observations, a PCR-based screening for dsrAB (key genes of the sulfate respiration pathway encoding the alpha and beta subunits of the dissimilatory sulfite reductase) of all enrichments/ (co) cultures was negative with one exception. Surprisingly, strain MGP contained dsrAB, which were transcribed in the presence and absence of sulfate. Based on these and previous findings, we hypothesize that members of Desulfotomaculum subcluster Ih have recently adopted a syntrophic lifestyle to thrive in low-sulfate, methanogenic environments and thus have lost their ancestral ability for dissimilatory sulfate/sulfite reduction.