Winfrey M R, Zeikus J G
Appl Environ Microbiol. 1977 Feb;33(2):275-81. doi: 10.1128/aem.33.2.275-281.1977.
The effect of sulfate on methane production in Lake Mendota sediments was investigated to clarify the mechanism of sulfate inhibition of methanogenesis. Methanogenesis was shown to be inhibited by the addition of as little as 0.2 mM sulfate. Sulfate inhibition was reversed by the addition of either H2 or acetate. Methane evolved when inhibition was reversed by H2 additions was derived from 14CO2. Conversely, when acetate was added to overcome sulfate inhibition, the evolved methane was derived from [2-14C]acetate. A competition for available H2 and acetate was proposed as the mechanism by which sulfate inhibited methanogenesis. Acetate was shown to be metabolized even in the absence of methanogenic activity. In the presence of sulfate, the methyl position of acetate was converted to CO2. The addition of sulfate to sediments did not result in the accumulation of significant amounts of sulfide in the pore water. Sulfate additions did not inhibit methanogenesis unless greater than 100 mug of free sulfide per ml was present in the pore water. These results indicate that carbon and electron flow are altered when sulfate is added to sediments. Sulfate-reducing organisms appear to assume the role of methanogenic bacteria in sulfate-containing sediments by utilizing methanogenic precursors.
研究了硫酸盐对门多塔湖沉积物中甲烷生成的影响，以阐明硫酸盐抑制甲烷生成的机制。结果表明，添加低至0.2 mM的硫酸盐即可抑制甲烷生成。添加氢气或乙酸盐可逆转硫酸盐的抑制作用。当通过添加氢气逆转抑制作用时，产生的甲烷来自14CO2。相反，当添加乙酸盐以克服硫酸盐抑制作用时，产生的甲烷来自[2-14C]乙酸盐。有人提出，对可用氢气和乙酸盐的竞争是硫酸盐抑制甲烷生成的机制。结果表明，即使在没有甲烷生成活性的情况下，乙酸盐也能被代谢。在有硫酸盐存在的情况下，乙酸盐的甲基位置会转化为二氧化碳。向沉积物中添加硫酸盐不会导致孔隙水中大量硫化物的积累。除非孔隙水中每毫升游离硫化物含量超过100微克，否则添加硫酸盐不会抑制甲烷生成。这些结果表明，向沉积物中添加硫酸盐时，碳和电子流会发生改变。在含硫酸盐的沉积物中，硫酸盐还原生物似乎通过利用甲烷生成前体承担了甲烷生成细菌的角色。
