Trace amounts of oxygen stimulate facultative anaerobic bacteria (FAB) within anaerobic bioreactors, which was shown to correlate with enhanced methane production from long-chain fatty acids. The relationship between FAB and fatty acid-degrading syntrophic communities under micro-aerobic conditions is still unclear. In this work, two syntrophic co-cultures, Syntrophomonas wolfei + Methanospirillum hungatei and Syntrophomonas zehnderi + Methanobacterium formicicum, were assembled and incubated with short, medium and long-chain fatty acids, with 0–10 % O2, in the presence and absence of FAB, here represented by Pseudomonas spp. Without Pseudomonas, the syntrophic activity was inhibited by 79 % at 0.5 % O2, but with Pseudomonas, the syntrophic co-cultures successfully converted the fatty acids to methane with up to 2 % O2. These findings underscore the pivotal role of FAB in the protection of syntrophic fatty acid-degrading communities under micro-aerobic conditions and emphasizes its significance in real-scale anaerobic digesters where strictly anaerobic conditions may not consistently be maintained.

中文翻译：

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兼性厌氧菌能够在微需氧条件下降解共养脂肪酸


微量的氧气会刺激厌氧生物反应器内的兼性厌氧菌 （FAB），这与长链脂肪酸产生的甲烷增加有关。在微需氧条件下，FAB 与脂肪酸降解共养群落之间的关系尚不清楚。在这项工作中，两种共养共培养物，即 Syntrophomonas wolfei + Methanospirillum hungatei 和 Syntrophomonas zehnderi + Methanobacterium formicicum，在存在和不存在 FAB 的情况下，与 0-10% O2 的短链、中链和长链脂肪酸一起孵育，这里以假单胞菌属为代表。在没有假单胞菌的情况下，在 0.5% O2 下，共养活性被抑制了 79%，但对于假单胞菌，共养共培养物成功地将脂肪酸转化为高达 2% O2 的甲烷。这些发现强调了 FAB 在微需氧条件下保护共养脂肪酸降解群落的关键作用，并强调了它在实际规模厌氧消化器中的重要性，因为严格的厌氧条件可能无法始终如一地维持。