Pyrosequencing reveals the key microorganisms involved in sludge alkaline fermentation for efficient short-chain fatty acids production.
Pyrosequencing reveals the key microorganisms involved in sludge alkaline fermentation for efficient short-chain fatty acids production.
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DOI：
10.1021/es400210v
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发表时间：
2013-04
影响因子：
11.4
通讯作者：
Xiong Zheng;Yinglong Su;Xiang Li;Naidong Xiao;Dong-bo Wang;Yinguang Chen
中科院分区：
文献类型：
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作者：
Xiong Zheng;Yinglong Su;Xiang Li;Naidong Xiao;Dong-bo Wang;Yinguang Chen
短链脂肪酸(SCFAs)被认为是废水生物脱氮的优良碳源，而污泥碱性(pH为10)发酵可实现SCFAs的高效生产。本研究通过454焦磷酸测序和荧光原位杂交(FISH)分析污泥发酵反应器中微生物群落结构，探讨了在pH为10的条件下提高单链脂肪酸产量的可能机制。结果表明，在pH为10的条件下进行污泥发酵可提高假单胞菌的丰度。和产碱菌，它们能分泌胞外蛋白酶和解聚酶，从而促进不溶性污泥蛋白和聚羟基烷酸酯(PHA)的降解。同时，产酸菌(如梭状芽孢杆菌Clostridium sp.)在pH为10的反应器中，pH值也高于未控制的pH值，有利于可溶性有机底物的酸化。进一步的研究表明，pH为10的污泥发酵显著减少了产甲烷古生菌的数量，从而减少了单链脂肪酸的消耗和甲烷的产生。因此，碱性条件下的厌氧污泥发酵增加了参与污泥水解和酸化的细菌的丰度，降低了产甲烷古菌的丰度，有利于细菌对产甲烷菌的竞争，从而导致单链脂肪酸的高效生产。
Short-chain fatty acids (SCFAs) have been regarded as the excellent carbon source of wastewater biological nutrient removal, and sludge alkaline (pH 10) fermentation has been reported to achieve highly efficient SCFAs production. In this study, the underlying mechanisms for the improved SCFAs production at pH 10 were investigated by using 454 pyrosequencing and fluorescent in situ hybridization (FISH) to analyze the microbial community structures in sludge fermentation reactors. It was found that sludge fermentation at pH 10 increased the abundances of Pseudomonas sp. and Alcaligenes sp., which were able to excrete extracellular proteases and depolymerases, and thus enhanced the hydrolysis of insoluble sludge protein and polyhydroxyalkanoates (PHA). Meanwhile, the abundance of acid-producing bacteria (such as Clostridium sp.) in the reactor of pH 10 was also higher than that of uncontrolled pH, which benefited the acidification of soluble organic substrates. Further study indicated that sludge fermentation at pH 10 significantly decreased the number of methanogenic archaea, resulting in lower SCFAs consumption and lower methane production. Therefore, anaerobic sludge fermentation under alkaline conditions increased the abundances of bacteria involved in sludge hydrolysis and acidification, and decreased the abundance of methanogenic archaea, which favored the competition of bacteria over methanogens and resulted in the efficient production of SCFAs.