Anaerobic metabolism of immediate methane precursors in Lake Mendota
Anaerobic metabolism of immediate methane precursors in Lake Mendota
复制标题
门多塔湖直接甲烷前体的厌氧代谢
DOI：
10.1128/aem.37.2.244-253.1979
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发表时间：
1979
影响因子：
4.4
通讯作者：
J. Zeikus
中科院分区：
文献类型：
--
作者：
M. Winfrey;J. Zeikus
为了更好地了解产甲烷前体H2/CO2和醋酸盐在自然界中的代谢，对门多塔湖沉积物和直接上覆水柱进行了研究。醋酸盐池尺寸很小(3.5微米M)，醋酸盐周转时间很快(0.22h)。溶解无机碳库大(6.4~8.3 mm)，周转时间慢(111H)。沉积物中产生的甲烷中，CO2占41+/-5.5%。乙酸盐和H2/CO2同时转化为CH4。在沉积物中加入H2后，H(14)CO3-生成的CH4比活度增加，[2-14C]乙酸酯生成的CH4比活度降低。乙酸酯的加入使H(14)CO3-的CH4比活度降低。H(14)CO3-或[2-14C]乙酸酯向14CH4的代谢不受乙酸盐或氢气的抑制。当添加的[2-14C]醋酸酯的99%以上被反转后，标记的42%被回收为14CH4，20%被回收为14CO2，38%被结合到沉积物中。对沉积物中[2-14C]乙酸酯代谢的抑制研究表明，CHCl3完全抑制了CH4的形成，但不能抑制CO2的产生。空气和硝酸盐的添加抑制了CH4的形成并刺激了CO2的产生，而氟乙酸酯的添加则完全抑制了乙酸酯的代谢。在添加Label之前孵育沉积物时，[2-14C]乙酸酯氧化为14CO2的反应随着时间的推移而减少，这表明内源沉积物电子受体的水平很低。醋酸盐代谢随季节变化，与湖水和间隙水中硫酸盐浓度有关。在湖泊层化期间，甲烷发生在沉积物及其上覆水中，在湖泊翻转时，在沉积物-水界面以下几厘米处发生。这些数据表明，门多塔湖沉积物中的甲烷生成受到甲烷前体“即时”可获得性(即乙酸盐和氢气)、非产甲烷菌对这些底物的竞争以及改变沉积物和水化学的季节性变化的限制。
Lake Mendota sediments and the immediate overlying water column were studied to better understand the metabolism of the methanogenic precursors H2/CO2 and acetate in nature. The pool size of acetate (3.5 microns M) was very small, and the acetate turnover time (0.22h) was very rapid. The dissolved inorganic carbon pool was shown to be large (6.4 to 8.3 mM), and the turnover time was slow (111 H.). CO2 was shown to account for 41 +/- 5.5% of the methane produced in sediment. Acetate and H2/CO2 were simultaneously converted to CH4. The addition of H2 to sediments resulted in an increase specific activity of CH4 from H(14)CO3- and a decrease in specific activity of CH4 from [2-14C]acetate. Acetate addition resulted in a decrease in specific activity of CH4 from H(14)CO3-. The metabolism of H(14)CO3- or [2-14C]acetate to 14CH4 was not inhibited by addition of acetate or H2. After greater than 99% of added [2-14C]acetate had been turned over, 42% of the label was recovered as 14CH4 20% was recovered as 14CO2 and 38% was incorporated into sediment. Inhibitor studies of [2-14C]acetate metabolism in sediments demonstrated that CHCl3 completely inhibited CH4 formation, but not CO2 production. Air and nitrate addition inhibited CH4 formation and stimulated CO2 production, whereas fluoroacetate addition totally inhibited acetate metabolism. The oxidation of [2-14C]acetate to 14CO2 was shown to decrease with time when sediment was incubated before the addition of label, suggesting depletion of low levels of an endogenous sediment electron acceptor. Acetate metabolism varied seasonally and was related to the concentration of sulfate in the lake and interstitial water. Methanogenesis occurred in the sediment and in the water immediately overlying the sediment during period of lake stratification and several centimeters below the sediment-water interface during lake turnovers. These data indicate that methanogenesis in Lake Mendota sediments was limited by "immediate" methane precursor availability (i.e., acetate and H2), by competition for these substrates by nonmethanogens, and by seasonal variations which altered sediment and water chemistry.