3种来源兼性纤维素分解菌与固氮菌混合对体外发酵的影响

Effects of Three Sources of Facultative Bacteria Cellulose Mixed with Nitrogen-fixing Bacteria on in Vitro Fermentation

本试验选取分离自瘤胃液、土壤、饲料中的3株高酶活性的兼性厌氧纤维素分解菌(L6、T1、S4)和3株低酶活性的兼性厌氧纤维素分解菌(L4、T4、S1),分别与自瘤胃内取提的1种兼性厌氧固氮菌(C5)以4:1混合,形成6种混合菌(记为L6、T1、S4、L4、T4、S1),通过体外培养试验来探讨其对体外发酵的影响。试验设置6个试验组和1个对照组,每组7个重复。向每个注射器内装入200 mg发酵底物(精:粗=45:55),与1 m L的混合菌液(对照组加入1 m L灭活的菌液)将培养液加至30 m L,进行体外发酵试验。发酵时间为24 h,分别记录2、4、8、12、24h的产气量,测定发酵指标。结果表明:与对照组相比,试验组对产气量、pH、氨态氮(NH_3-N)、菌体蛋白(MCP)、挥发性脂肪酸(VFA)及滤纸纤维素酶活性均有显著影响(P<0.05),其中L4试验组对VFA、NH_3-N及滤纸纤维素酶活等影响效果最好;与高酶活试验组相比,低酶活试验组对产气量、pH、VFA浓度及NH_3-N浓度有显著影响(P<0.05),对MCP浓度和滤纸纤维素酶活性没有显著影响(P>0.05)。由此可见,添加的混合菌对体外发酵有明显促进作用,其中L4试验组对体外发酵的影响效果最好;低酶活性的兼性纤维素分解菌对体外发酵的促进作用比高酶活性的兼性纤维素分解菌好。

In this trial, 3 strains with high activity of facultative anaerobic cellulolytic bacteria （L6, T1, S4）and 3 strainsof low enzyme activity of facultative anaerobic cellulolytic bacteria （L4, T4, S1）which were isolated from rumen fluid,soil and feed, respectively. Then individually mixed them with the same nitrogen-fixing bacteria in 4：1 ration （markedseparately L6, T1, $4, L4, T4, S1）, their effect on in vitro fermentation was studied by in vitro culture. The study wasdivided into 6 experimental groups, 1 control groups, each group with 7 replicates. Each syringe was put into 200 mg of thefermentation substrate （The ratio of concentrate to roughage = 45：55）, and 1 mL of mixed bacteria （1 mL of the inactivatedbacteria was added to the control group）, Finally, the culture medium was added to 30 mL, in vitro fermentation. Thefermentation time was 24 h, and the gas production was recorded at 2, 4, 8, 12 and 24 h, respectively, the results basedon the determination of fermentation index showed that the experimental group indicated significant difference （P〈0.05）on the gas production, pH, ammonia nitrogen （NH3-N）, protein （MCP）, volatile fatty acids （VFA） and cellulase activitycompared with the control group. The L4 test group showed the best effect on VFA, NH3-N and cellulase activity comparedwith others; meanwhile, low fiber enzyme group had significant difference （P〈0.05） on the gas production, pH, VFA,NH3-N concentration compared with high enzyme activity group, however, MCP and cellulase activity was not significantlydifference （P〉0.05） between them. The results showed that the addition of culture of mixed bacteria has a significant effecton in vitro fermentation, the effect of L4 test group on in vitro fermentation was the best. The low cellulase activity offacultative fibrils is better for in vitro fermentation than synergistic fibrils with high cellulase activity.