Goh Falicia, Allen Michelle A, Leuko Stefan, Kawaguchi Tomohiro, Decho Alan W, Burns Brendan P, Neilan Brett A
School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia.
ISME J. 2009 Apr;3(4):383-96. doi: 10.1038/ismej.2008.114. Epub 2008 Dec 18.
The stromatolites at Shark Bay, Western Australia, are analogues of some of the oldest evidence of life on Earth. The aim of this study was to identify and spatially characterize the specific microbial communities associated with Shark Bay intertidal columnar stromatolites. Conventional culturing methods and construction of 16S rDNA clone libraries from community genomic DNA with both universal and specific PCR primers were employed. The estimated coverage, richness and diversity of stromatolite microbial populations were compared with earlier studies on these ecosystems. The estimated coverage for all clone libraries indicated that population coverage was comprehensive. Phylogenetic analyses of stromatolite and surrounding seawater sequences were performed in ARB with the Greengenes database of full-length non-chimaeric 16S rRNA genes. The communities identified exhibited extensive diversity. The most abundant sequences from the stromatolites were alpha- and gamma-proteobacteria (58%), whereas the cyanobacterial community was characterized by sequences related to the genera Euhalothece, Gloeocapsa, Gloeothece, Chroococcidiopsis, Dermocarpella, Acaryochloris, Geitlerinema and Schizothrix. All clones from the archaeal-specific clone libraries were related to the halophilic archaea; however, no archaeal sequence was identified from the surrounding seawater. Fluorescence in situ hybridization also revealed stromatolite surfaces to be dominated by unicellular cyanobacteria, in contrast to the sub-surface archaea and sulphate-reducing bacteria. This study is the first to compare the microbial composition of morphologically similar stromatolites over time and examine the spatial distribution of specific microorganismic groups in these intertidal structures and the surrounding seawater at Shark Bay. The results provide a platform for identifying the key microbial physiology groups and their potential roles in modern stromatolite morphogenesis and ecology.
西澳大利亚鲨鱼湾的叠层石是地球上一些最古老生命证据的类似物。本研究的目的是识别与鲨鱼湾潮间带柱状叠层石相关的特定微生物群落，并对其进行空间特征描述。采用了传统培养方法以及使用通用和特异性PCR引物从群落基因组DNA构建16S rDNA克隆文库。将叠层石微生物种群的估计覆盖率、丰富度和多样性与这些生态系统的早期研究进行了比较。所有克隆文库的估计覆盖率表明种群覆盖范围是全面的。利用全长非嵌合16S rRNA基因的Greengenes数据库在ARB中对叠层石和周围海水序列进行了系统发育分析。所识别的群落表现出广泛的多样性。叠层石中最丰富的序列是α-和γ-变形菌（58%），而蓝藻群落的特征是与真盐生蓝细菌属、粘球藻属、胶鞘藻属、拟色球藻属、皮果藻属、聚球藻属、席藻属相关的序列。古菌特异性克隆文库中的所有克隆均与嗜盐古菌相关；然而，在周围海水中未鉴定出古菌序列。荧光原位杂交还显示，与地下古菌和硫酸盐还原细菌相比，叠层石表面以单细胞蓝藻为主。本研究首次比较了不同时间形态相似的叠层石的微生物组成，并研究了这些潮间带结构及鲨鱼湾周围海水中特定微生物群体的空间分布。研究结果为识别关键微生物生理类群及其在现代叠层石形态发生和生态学中的潜在作用提供了一个平台。
