两株低温沼气产酸细菌的分离鉴定及产酸特性

Isolation，identification and characterization of acidproducing strains from psychrotolerant biogas fermentation

摘要:

摘要:【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。

关键词:关键词:产酸，鉴定，挥发性脂肪酸，低温，沼气发酵

Abstract:

Abstract:［Objective］The aim of this study was to screen acid-producing strains from the broth of psychrotolerant biogas fermentation and evaluate the acid-producing character of them.［Methods］Acid-producing strains were isolated by a medium with methyl red at 4 ℃ in Petri dishes and identified by morphology observation and 16S rRNA sequencing．Moreover，the ability of hydrolysis of starch，fermentation of carbohydrates，liquefaction of gelatin and production of catalase were studied．［Results］Two acid-producing strains (FJ-8 and FJ-15) were isolated． The result of the 16S rRNA phylogenetic tree shows that FJ-8 and FJ-15 belong to Pseudomonas sp． and Shewanella sp.，respectively． Both FJ-8 and FJ-15 could hydrolyze starch，liquidize gelatin and produce catalase． The optimum temperature for acid-producing of FJ-8 and FJ-15 is 15 ℃ and 20 ℃，respectively． After 10 days cultivation at 4 ℃，the concentration of acetic acid was 792 mg/L and 966 mg/L of FJ-8 and FJ-15 ，respectively.［Conclusion］The selected strains，FJ-8 and FJ-15，have the potential to produce acids at low temperature.

Key words:Keywords: acid-producing，identification，volatile fatty acid，low temperature，biogas fermentation