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【目的】分离筛选低温沼气产酸细菌并研究其发酵特性。【方法】利用筛选培养基分离产酸细菌;通过形态学观察、16S rRNA进行鉴定;利用糖发酵、淀粉水解、明胶液化、过氧化氢酶等实验考察发酵特性;采用气相色谱法测定挥发性脂肪酸(Volatile fatty acid,VFA),对菌株的产酸特性进行研究。【结果】从霍林河市户用沼液中分离出两株在4℃产酸较高的菌株FJ-8和FJ-15,经16S rRNA系统发育树分析分别属于Pseudomonas sp.和Shewanella sp.。两株菌均能够水解淀粉、液化明胶,且过氧化氢酶反应均呈阳性。它们最适的产酸温度分别是15℃和20℃,在4℃液体发酵10 d后所产总VFAs分别为2593 mg/L和2687 mg/L。其中乙酸含量分别为792 mg/L和966 mg/L。另外,相同条件下5 L模拟发酵结果显示处理组(添加所筛两株菌混合发酵液)的周产气量比对照组高出59%。【结论】分离出的两株产酸细菌FJ-8和FJ-15在低温条件下具有较好的产酸性能,在提高低温条件下沼气产气量方面具有很强的应用前景。
【Objective】 Isolation and screening of acidogenic bacteria in low temperature biogas and their fermentation characteristics were studied. 【Method】 The acid-producing bacteria were isolated by screening medium. The 16S rRNA was identified by morphological observation. The fermentation characteristics were investigated by sugar fermentation, starch hydrolysis, gelatin liquefaction and catalase. The volatile fatty acids (Volatile fatty acid, VFA) to study the acidogenicity of the strain. 【Result】 Two strains FJ-8 and FJ-15 which had higher acidogenicity at 4 ℃ were isolated from the household biogas slurry in Huolinhe City. The 16S rRNA phylogenetic tree analyzes belong to Pseudomonas sp. And Shewanella sp. Respectively. . Both strains were able to hydrolyze starch, liquefy gelatin, and catalase reactions were positive. Their optimal acidogenic temperatures were 15 ℃ and 20 ℃, respectively. The total VFAs produced by liquid fermentation at 4 ℃ for 10 d were 2593 mg / L and 2687 mg / L, respectively. Acetic acid content was 792 mg / L and 966 mg / L, respectively. In addition, the results of 5 L simulated fermentation under the same conditions showed that the weekly gas production of the treatment group (adding the two strains of mixed fermentation broth) was 59% higher than that of the control group. 【Conclusion】 The two isolated acid-producing bacteria, FJ-8 and FJ-15, have good acid-producing properties under low temperature and have strong application prospect in improving biogas gas production under low temperature.