C/N对污泥厌氧发酵产酸类型及代谢途径的影响

研究了污泥的初始C/N对污泥发酵产酸类型的影响及产酸代谢途径.初始C/N在12时,形成的是乙酸型发酵类型;当初始C/N在56左右,可实现丙酸型发酵类型;而当C/N处于156时,则形成丁酸型发酵.不同发酵产酸类型的形成是由优势产酸菌群的改变导致的.末端限制性片段长度多态性分析(T-RFLP)微生物种群的结果表明,构成乙酸型发酵类型的主要优势菌群为消化链球菌属;而丙酸型发酵类型中的优势菌群则为丙酸杆菌属;梭菌属则是丁酸型发酵类型中的优势产酸功能菌.有机酸代谢途径中关键酶活性检测结果表明,在低C/N条件下,乙酸的累积主要是通过氨基酸之间的Stickland反应形成,而随着C/N值的增大,导致丙酸和丁酸累积的主要代谢途径转变为糖酵解的丙酮酸途径.

The effects of C/N ratio on the production of volatile fatty acids and the metabolic pathway of anaerobic fermentation of sewage sludge

The effects of initial carbon-nitrogen ratio on the metabolic pathway leading to volatile fatty acid (VFA) production were investigated during anaerobic fermentation of sewage sludge. When the initial C/N ratio was 12, the main product was acetic acid, while propionic and acetic acids became the main products at an initial C/N of 56. With the increase of initial C/N to 156, butyric acid became the dominant volatile fatty acid. The shift of the acid fermentation type partly resulted from the change of the dominant bacterial populations in the system. During acetate type fermentation, the acetic acid-producing bacterial genus Peptostreptococcus was dominant. In propionate fermentation, the propionic acid-producing bacteria genus Propionibacterium became dominant. For the butyrate type fermentation, Clostridium dominated the bacterial community in the sludge. With the increase of C/N ratio, the main metabolic pathway resulting in the accumulation of the predominant VFA changed from the Stickland reaction to the pyruvic acid pathway of glycolysis.