Haaijer Suzanne C M, Crienen Gijs, Jetten Mike S M, Op den Camp Huub J M
Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen Nijmegen, Netherlands.
Front Microbiol. 2012 Feb 3;3:26. doi: 10.3389/fmicb.2012.00026. eCollection 2012.
In this study, both culture-dependent and culture-independent methods were used to determine whether the iron sulfide mineral- and nitrate-rich freshwater nature reserve Het Zwart Water accommodates anoxic microbial iron cycling. Molecular analyses (16S rRNA gene clone library and fluorescence in situ hybridization, FISH) showed that sulfur-oxidizing denitrifiers dominated the microbial population. In addition, bacteria resembling the iron-oxidizing, nitrate-reducing Acidovorax strain BrG1 accounted for a major part of the microbial community in the groundwater of this ecosystem. Despite the apparent abundance of strain BrG1-like bacteria, iron-oxidizing nitrate reducers could not be isolated, likely due to the strictly autotrophic cultivation conditions adopted in our study. In contrast an iron-reducing Geobacter sp. was isolated from this environment while FISH and 16S rRNA gene clone library analyses did not reveal any Geobacter sp.-related sequences in the groundwater. Our findings indicate that iron-oxidizing nitrate reducers may be of importance to the redox cycling of iron in the groundwater of our study site and illustrate the necessity of employing both culture-dependent and independent methods in studies on microbial processes.
在本研究中，采用了依赖培养和不依赖培养的方法来确定富含硫化铁矿物和硝酸盐的淡水自然保护区黑沃特是否存在缺氧微生物铁循环。分子分析（16S rRNA基因克隆文库和荧光原位杂交，FISH）表明，硫氧化反硝化菌在微生物群落中占主导地位。此外，类似于铁氧化、硝酸盐还原嗜酸菌菌株BrG1的细菌在该生态系统地下水中的微生物群落中占主要部分。尽管类似菌株BrG1的细菌明显丰富，但由于本研究采用了严格的自养培养条件，铁氧化硝酸盐还原菌未能分离出来。相比之下，从该环境中分离出了一种铁还原地杆菌属细菌，而FISH和16S rRNA基因克隆文库分析并未在地下水中发现任何与地杆菌属相关的序列。我们的研究结果表明，铁氧化硝酸盐还原菌可能对我们研究地点地下水中铁的氧化还原循环具有重要意义，并说明了在微生物过程研究中采用依赖培养和不依赖培养方法的必要性。
