Functional Gene Analysis of Freshwater Iron-Rich Flocs at Circumneutral pH and Isolation of a Stalk-Forming Microaerophilic Iron-Oxidizing Bacterium
Functional Gene Analysis of Freshwater Iron-Rich Flocs at Circumneutral pH and Isolation of a Stalk-Forming Microaerophilic Iron-Oxidizing Bacterium
复制标题
DOI：
10.1128/aem.03840-12
复制
发表时间：
2013-09-01
影响因子：
4.4
通讯作者：
Ohkuma, Moriya
中科院分区：
文献类型：
--
作者：
Kato, Shingo;Chan, Clara;Ohkuma, Moriya
富铁絮体经常出现在含铁的缺氧水遇到含氧环境的地方。独立于培养的分子分析揭示了与不同细菌相关的16S rRNA基因序列，包括富铁絮体中的自养铁氧化菌和甲烷氧化菌；然而，微生物群落的代谢功能仍然缺乏特征，特别是在碳循环方面。在本研究中，我们培养了氧化铁细菌(FeOB)，并对地下水排泄点富铁淡水絮体中与固碳和甲烷氧化相关的功能基因(分别为cbbM和pmoA)以及细菌和古生菌的16S rRNA基因进行了克隆文库分析。对16S rRNA、cbbM和pmoA基因的分析表明，絮体中存在自养铁氧化菌和甲烷氧化菌。此外，还分离到了一株新的秸秆形成微生物FeOB菌株OYT1，并对其系统发育和生理特性进行了研究。OYT1的16S rRNA和cbbM基因序列与大蒜科其他嗜氧FeOB基因和贝塔蛋白细菌的16S rRNA和cbbM基因序列有关，这些FeOB是从淡水环境中分离出来的。OYT1的生理特性将有助于阐明微好氧FeOB的生态生理学。总体而言，这项研究证明了微生物在铁絮体中的功能作用，暗示了铁和碳循环之间的几种可能的联系。
Iron-rich flocs often occur where anoxic water containing ferrous iron encounters oxygenated environments. Culture-independent molecular analyses have revealed the presence of 16S rRNA gene sequences related to diverse bacteria, including autotrophic iron oxidizers and methanotrophs in iron-rich flocs; however, the metabolic functions of the microbial communities remain poorly characterized, particularly regarding carbon cycling. In the present study, we cultivated iron-oxidizing bacteria (FeOB) and performed clone library analyses of functional genes related to carbon fixation and methane oxidization (cbbM and pmoA, respectively), in addition to bacterial and archaeal 16S rRNA genes, in freshwater iron-rich flocs at groundwater discharge points. The analyses of 16S rRNA, cbbM, and pmoA genes strongly suggested the coexistence of autotrophic iron oxidizers and methanotrophs in the flocs. Furthermore, a novel stalk-forming microaerophilic FeOB, strain OYT1, was isolated and characterized phylogenetically and physiologically. The 16S rRNA and cbbM gene sequences of OYT1 are related to those of other microaerophilic FeOB in the family Gallionellaceae, of the Betaproteobacteria, isolated from freshwater environments at circum-neutral pH. The physiological characteristics of OYT1 will help elucidate the ecophysiology of microaerophilic FeOB. Overall, this study demonstrates functional roles of microorganisms in iron flocs, suggesting several possible linkages between Fe and C cycling.