期刊
ISME JOURNAL
卷 6, 期 4, 页码 863-874出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/ismej.2011.142
关键词
microbial mats; fermentation; hydrogen; hydrogenase; Microcoleus spp.; pyrotags
资金
- U.S. Department of Energy (DOE) [SCW1039]
- U.S. Department of Energy at Lawrence Livermore National Laboratory [DE-AC52-07NA27344]
- U.S. Department of Energy at Lawrence Berkeley National Laboratory [DE-AC02-05CH11231]
- German Research Foundation (Deutsche Forschungsgemeinschaft)
Hydrogen (H-2) release from photosynthetic microbial mats has contributed to the chemical evolution of Earth and could potentially be a source of renewable H-2 in the future. However, the taxonomy of H-2-producing microorganisms (hydrogenogens) in these mats has not been previously determined. With combined biogeochemical and molecular studies of microbial mats collected from Elkhorn Slough, Monterey Bay, California, we characterized the mechanisms of H-2 production and identified a dominant hydrogenogen. Net production of H-2 was observed within the upper photosynthetic layer (0-2 mm) of the mats under dark and anoxic conditions. Pyrosequencing of rRNA gene libraries generated from this layer demonstrated the presence of 64 phyla, with Bacteriodetes, Cyanobacteria and Proteobacteria dominating the sequences. Sequencing of rRNA transcripts obtained from this layer demonstrated that Cyanobacteria dominated rRNA transcript pyrotag libraries. An OTU affiliated to Microcoleus spp. was the most abundant OTU in both rRNA gene and transcript libraries. Depriving mats of sunlight resulted in an order of magnitude decrease in subsequent nighttime H-2 production, suggesting that newly fixed carbon is critical to H-2 production. Suppression of nitrogen (N-2)-fixation in the mats did not suppress H-2 production, which indicates that co-metabolic production of H-2 during N-2-fixation is not an important contributor to H-2 production. Concomitant production of organic acids is consistent with fermentation of recently produced photosynthate as the dominant mode of H-2 production. Analysis of rRNA % transcript: % gene ratios and H-2-evolving bidirectional [NiFe] hydrogenase % transcript:% gene ratios indicated that Microcoelus spp. are dominant hydrogenogens in the Elkhorn Slough mats. The ISME Journal (2012) 6, 863-874; doi: 10.1038/ismej.2011.142; published online 20 October 2011
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