ROLE OF INTERSPECIES H-2 TRANSFER TO SULFATE AND FERRIC IRON-REDUCING BACTERIA IN ACETATE CONSUMPTION IN ANOXIC PADDY SOIL
ROLE OF INTERSPECIES H-2 TRANSFER TO SULFATE AND FERRIC IRON-REDUCING BACTERIA IN ACETATE CONSUMPTION IN ANOXIC PADDY SOIL
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DOI：
10.1111/j.1574-6941.1995.tb00269.x
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发表时间：
1995-01-01
影响因子：
4.2
通讯作者：
CONRAD, R
中科院分区：
文献类型：
--
作者：
ACHTNICH, C;SCHUHMANN, A;CONRAD, R
硫酸盐的添加导致缺氧水稻土甲烷生成的完全抑制。约20%的CH 4由H-2/（CO2）-C-14生成，其余由-乙酸生成。抑制H-2-依赖的产甲烷被解释为成功的竞争硫酸盐还原剂的H-2，作为H-2分压下降后，加入硫酸盐。然而，乙酸盐浓度并未降低。硫酸盐还原刺激H-2，但不是由乙酸。利用乙酸盐的硫酸盐还原菌的计数在新鲜和巴氏灭菌的土壤中都相对较低，表明细菌仅以孢子形式存在。氯仿抑制甲烷生成导致H-2和乙酸的积累。当另外加入硫酸盐时，H-2积累停止，但乙酸盐仍然积累，表明产甲烷菌的活性对于乙酸盐转化是必需的，并且乙酸盐不能被硫酸盐还原剂直接利用。当加入硫酸盐时，[2-C-14]乙酸酯的转化导致形成相对更多的（CO2）-C-14，表明乙酸酯的甲基现在被氧化而不是还原。氯仿的加入强烈抑制了[2-C-14]乙酸酯的转化，即使在硫酸盐的存在下。一个可能的解释是硫酸盐依赖的物种间H-2转移之间的乙酸盐利用产甲烷菌和H-2利用硫酸盐还原剂，改变电子现在从甲烷生产硫酸盐还原。添加水铁矿只会导致不完全抑制甲烷生成，这可以解释为成功的竞争的三价铁还原剂H-2。三价铁还原剂能够直接利用乙酸盐，但不能胜过产甲烷菌。
Addition of sulfate resulted in complete inhibition of methanogenesis in anoxic paddy soil. About 20% of the CH4 was produced from H-2/(CO2)-C-14, the rest from-acetate. Inhibition of H-2-dependent methanogenesis was explained by successful competition by sulfate reducers for H-2, as the H-2 partial pressures decreased upon addition of sulfate. However, acetate concentrations did not decrease. Sulfate reduction was stimulated by H-2, but not by acetate. Counts of acetate-utilizing sulfate reducers were relatively low both in fresh and pasteurized soil indicating that the bacteria were only present as spores. Inhibition of methanogenesis by chloroform resulted in accumulation of both H-2 and acetate. When sulfate was added in addition, H-2 accumulation stopped, but acetate still accumulated indicating that the activity of the methanogens was necessary for acetate conversion and that acetate could not be utilized by the sulfate reducers directly. Conversion of [2-C-14]acetate resulted in formation of relatively more (CO2)-C-14, when sulfate was added, indicating that the methyl group of acetate was now being oxidized instead of reduced. Addition of chloroform strongly inhibited the conversion of [2-C-14]acetate, even in the presence of sulfate. A conceivable explanation is sulfate-dependent interspecies H-2 transfer between acetate-utilizing methanogens and H-2-utilizing sulfate reducers, changing the electron now from CH4 production to sulfate reduction. Addition of ferrihydrite resulted only in incomplete inhibition of methanogenesis which could be explained by successful competition of ferric iron reducers for H-2. The ferric iron reducers were able to use acetate directly, but did not outcompete the methanogens.