Department of Microbiology, Montana State University, Bozeman, Montana 59717.
Appl Environ Microbiol. 1987 Oct;53(10):2343-52. doi: 10.1128/aem.53.10.2343-2352.1987.
The fate of representative fermentation products (acetate, propionate, butyrate, lactate, and ethanol) in hot spring cyanobacterial mats was investigated. The major fate during incubations in the light was photoassimilation by filamentous bacteria resembling Chloroflexus aurantiacus. Some metabolism of all compounds occurred under dark aerobic conditions. Under dark anaerobic conditions, only lactate was oxidized extensively to carbon dioxide. Extended preincubation under dark anaerobic conditions did not enhance anaerobic catabolism of acetate, propionate, or ethanol. Acetogenesis of butyrate was suggested by the hydrogen sensitivity of butyrate conversion to acetate and by the enrichment of butyrate-degrading acetogenic bacteria. Accumulation of fermentation products which were not catabolized under dark anaerobic conditions revealed their importance. Acetate and propionate were the major fermentation products which accumulated in samples collected at temperatures ranging from 50 to 70 degrees C. Other organic acids and alcohols accumulated to a much lesser extent. Fermentation occurred mainly in the top 4 mm of the mat. Exposure to light decreased the accumulation of acetate and presumably of other fermentation products. The importance of interspecies hydrogen transfer was investigated by comparing fermentation product accumulation at a 65 degrees C site, with naturally high hydrogen levels, and a 55 degrees C site, where active methanogenesis prevented significant hydrogen accumulation. There was a greater relative accumulation of reduced products, notably ethanol, in the 65 degrees C mat.
研究了温泉蓝藻垫中代表性发酵产物（乙酸盐、丙酸盐、丁酸盐、乳酸盐和乙醇）的命运。在光照下孵育期间，主要命运是类似于黄化菌属的丝状细菌的光同化作用。所有化合物在有氧黑暗条件下都会发生一些代谢。在黑暗厌氧条件下，只有乳酸盐被广泛氧化为二氧化碳。在黑暗厌氧条件下进行延长的预孵育不会增强乙酸盐、丙酸盐或乙醇的厌氧分解代谢。丁酸盐的乙酰生成作用由丁酸盐转化为乙酸盐的氢气敏感性和丁酸盐降解产乙酸菌的富集所暗示。未在黑暗厌氧条件下分解代谢的发酵产物的积累揭示了它们的重要性。在 50 至 70°C 的温度范围内采集的样品中，积累了主要的未被分解代谢的发酵产物乙酸盐和丙酸盐。其他有机酸和醇类积累的程度要小得多。发酵主要发生在垫子的前 4 毫米处。暴露在光线下会减少乙酸盐和可能的其他发酵产物的积累。通过比较具有高自然氢水平的 65°C 点和阻止显著氢积累的 55°C 点的发酵产物积累情况，研究了种间氢转移的重要性。在 65°C 的垫子中，还原产物（特别是乙醇）的相对积累更大。
