Kaspar H F, Wuhrmann K
Appl Environ Microbiol. 1978 Jul;36(1):1-7. doi: 10.1128/aem.36.1.1-7.1978.
The kinetics of propionate degradation, acetate splitting, and hydrogen consumption in digesting sludge were investigated in a lab-scale digester. At natural steady-state conditions, the acetate-splitting systems in well-digested sludge were about half saturated. Propionate-degrading systems were saturated to only 10 to 15%, and hydrogen removal was less than 1% of the maximum possible rate. It was concluded that acetate splitting rather than "methanogenesis from fatty acids" is the rate-limiting reaction in the anaerobic degradation of dissolved organic matter and that a methoanogenic anaerobic ecosystem is stabilized by its large unused capacity of hydrogen consumption which is "buffering" the partial pressure of dissolved hydrogen in the system at sufficiently low values to permit rapid fatty acid oxidation. A tentative scheme of the substrate flow in sludge digestion is presented. It suggests that acid formation coupled with hydrogen formation via pyridine dinucleotide oxidation yields the immediate substrates, namely acetate and hydrogen, for about 54% of the total methanogenesis.
在实验室规模的消化器中研究了消化污泥中丙酸降解、乙酸分解和氢气消耗的动力学。在自然稳态条件下，消化良好的污泥中的乙酸分解系统约为半饱和状态。丙酸降解系统的饱和度仅为10%至15%，氢气去除量不到最大可能速率的1%。得出的结论是，乙酸分解而非“脂肪酸产甲烷”是溶解有机物厌氧降解中的限速反应，并且产甲烷厌氧生态系统通过其大量未利用的氢气消耗能力得以稳定，这种能力将系统中溶解氢的分压“缓冲”到足够低的值，以允许脂肪酸快速氧化。提出了污泥消化中底物流动的初步方案。该方案表明，通过吡啶二核苷酸氧化形成酸并同时形成氢气，产生了约占总产甲烷量54%的直接底物，即乙酸和氢气。
