Department of Ecological Microbiology, University of Bayreuth, Bayreuth 95440, Germany.
FEMS Microbiol Ecol. 2021 Nov 13;97(11). doi: 10.1093/femsec/fiab143.
Fen Schlöppnerbrunnen is a moderately acidic methane-emitting peatland overgrown by Molinia caerulea and other wetland graminoids (e.g. Carex rostrata). Recently, the accumulation of H2, an indicator for fermentation, was observed with anoxically incubated C. rostrata roots but not with root-free fen soil. Based on this finding, we hypothesized that root-derived organic carbon has a higher capacity to promote fermentation processes than peat organic carbon from root-free fen soil. To address this hypothesis, C. rostrata and M. caerulea roots were anoxically incubated with or without fen soil and the product profiles of root treatments were compared with those of root-free soil treatments. Ethanol, acetate, propionate, butyrate, H2 and CO2 accumulated in root treatments and collective amounts of carbon in accumulating products were 20-200 times higher than those in root-free soil treatments, in which mainly CO2 accumulated. Analyses of 16S rRNA and 16S rRNA gene sequences revealed that Clostridium, Propionispira and Rahnella, representatives of butyrate, propionate and mixed acid fermenters, respectively, were relatively enriched in root treatments. In contrast, differences of the microbial community before and after incubation were marginal in root-free soil treatments. Collectively, these findings supported the assumed stimulatory effect of root-derived organic carbon on fen fermenters.
芬斯克洛普纳布伦嫩是一个中等酸性的产甲烷泥炭地，长满了蓝色羊茅和其他湿地禾本科植物（如罗氏酸模）。最近，在缺氧培养的罗氏酸模根中观察到 H2 的积累，这是发酵的一个指标，但在无根沼泽土中则没有。基于这一发现，我们假设根源性有机碳比无根沼泽土中的泥炭有机碳更能促进发酵过程。为了验证这一假设，我们对罗氏酸模和蓝色羊茅的根进行了缺氧培养，有无沼泽土，并比较了根处理和无根土壤处理的产物分布。在根处理中积累了乙醇、乙酸、丙酸、丁酸、H2 和 CO2，而在无根土壤处理中主要积累了 CO2，累积产物中的碳总量是无根土壤处理的 20-200 倍。16S rRNA 和 16S rRNA 基因序列分析显示，丁酸、丙酸和混合酸发酵菌的代表，如梭菌属、丙酸螺旋菌属和 Rahnella 属，在根处理中相对富集。相比之下，无根土壤处理中培养前后微生物群落的差异较小。总之，这些发现支持了根源性有机碳对沼泽发酵菌的刺激作用假设。
