Aquatic Geomicrobiology Group, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany.
FEMS Microbiol Ecol. 2012 Aug;81(2):339-54. doi: 10.1111/j.1574-6941.2012.01352.x. Epub 2012 Apr 4.
Acetate is a central intermediate in the anaerobic degradation of organic matter, and the resolution of its metabolism necessitates integrated strategies. This study aims to (1) estimate the contribution of acetogenesis to acetate formation in an acidic fen (pH ~ 4.9), (2) assess the genetic potential for acetogenesis targeting the fhs gene encoding formyltetrahydrofolate synthetase (FTHFS) and (3) unravel the in situ turnover of acetate using stable carbon isotope pore-water analysis. H(2)/CO(2)-supplemented peat microcosms yielded (13)C-depleted acetate (-37.2‰ vs. VPDB (Vienna Peedee belemnite standard) compared with -14.2‰ vs. VPDB in an unamended control), indicating the potential for H(2)-dependent acetogenesis. Molecular analysis revealed a high diversity and depth-dependent distribution of fhs phylotypes with the highest number of operational taxonomic units in 0-20 cm depth, but only few and distant relationships to known acetogens. In pore waters, acetate concentrations (0-170 μM) and δ(13)C-values varied widely (-17.4‰ to -3.4‰ vs. VPDB) and did not indicate acetogenesis, but pointed to a predominance of sinks, which preferentially consumed (12)C-acetate, like acetoclastic methanogenesis. However, depth profiles of methane and δ(13)C(CH4) revealed a temporarily and spatially restricted role of this acetate sink and suggest other processes like sulfate and iron reduction played an important role in acetate turnover.
乙酸盐是有机物质厌氧降解的中心中间产物，其代谢的解决需要综合策略。本研究旨在：（1）估计产乙酸作用对酸性沼泽（pH~4.9）中乙酸盐形成的贡献，（2）评估针对编码甲酰四氢叶酸合成酶（FTHFS）的 fhs 基因的产乙酸作用的遗传潜力，（3）使用稳定碳同位素孔隙水分析揭示原位乙酸盐的转化。补充了 H2/CO2 的泥炭微宇宙产生了（13）C 贫乏的乙酸盐（-37.2‰相对于 VPDB（维也纳皮迪比姆尼乌斯标准），而未添加对照中的-14.2‰相对于 VPDB），表明存在 H2 依赖性产乙酸作用的潜力。分子分析揭示了 fhs 类群的高度多样性和深度依赖性分布，在 0-20 厘米深度的操作分类单位数量最多，但与已知产乙酸菌的关系很少且很远。在孔隙水中，乙酸盐浓度（0-170 μM）和 δ（13）C 值变化很大（-17.4‰至-3.4‰相对于 VPDB），并不表明产乙酸作用，但表明存在优先消耗（12）C-乙酸盐的汇，如乙酸盐依赖性甲烷生成。然而，甲烷和 δ（13）C（CH4）的深度分布揭示了这种乙酸盐汇的暂时和空间限制作用，并表明其他过程，如硫酸盐和铁还原，在乙酸盐转化中发挥了重要作用。
