瘤胃纤维素降解细菌和真菌的互作对纤维物质降解的影响

发布时间：2019-06-15 11:06

【摘要】：本试验在前期体内群体研究的基础上,选择2株瘤胃厌氧真菌和3株纤维降解细菌,进行单一培养、混合培养和序列培养,研究菌株之间的相互关系；再以不同碳源进行培养,明确碳源组成对瘤胃厌氧真菌和纤维降解细菌互作关系的影响；并结合同位素示踪技术,以13C标记的纯纤维素作为菌株培养的发酵底物,精确追踪纤维降解的去路问题,更准确的来评价研究瘤胃厌氧真菌和细菌在纤维降解中的贡献及相互作用。试验结果表明,经纤维降解特性的研究发现拜氏梭菌、粪肠球菌、白色瘤胃球菌、Neocallimastix属菌和Cyllamyces属菌纤维降解情况及生长状态良好。拜氏梭菌分别与肠球菌、Neocallimastix属菌混合培养具有促进发酵的作用,而拜氏梭菌与Cyllamyces属菌混合培养无明显作用,拜氏梭菌与白色瘤胃球菌混合培养出现抑制发酵的现象；白色瘤胃球菌分别与肠球菌、Neocallimastix属菌、Cyllamyces属菌混合培养有抑制作用；肠球菌与Neocallimastix属菌混合培养有促进作用；Cyllamyces属菌分别与肠球菌、Neocallimastix属菌混合培养无明显的相互作用。进一步做序列培养后发现,拜氏梭菌、粪肠球菌与白色瘤胃球菌之间存在相互影响。纤维降解细菌与厌氧真菌混合培养若为促进作用,则是厌氧真菌促进了纤维降解细菌；纤维降解细菌与厌氧真菌混合培养若为抑制作用,则是纤维降解细菌抑制了厌氧真菌。混合培养的促进作用主要是由前一株菌的代谢产物引起的,但是干物质降解率的增加还是由于纤维结合位点的作用；混合培养中菌体蛋白浓度、产气量的抑制作用的原因表现在代谢产物与纤维结合位点,氨氮浓度、TVFA、滤纸酶活力的抑制的根源在纤维结合位点。经过三种不同比例的碳源比较,粗料与精料比为7：3的组合其微生物产量、降解率、VFA和NH3-N浓度等指标的结果较好,反映了此组合利于微生物的生长及对底物的发酵与利用。通过对底物纤维素添加13C同位素进行示踪可知,单一培养时纤维素的主要去路为VFA,混合培养时,VFA中的13C丰度急剧减少。在纤维素与淀粉为7：3时,碳的主要去路为VFA,气体中的碳比例有所增加。
[Abstract]:On the basis of the previous population study in vivo, two strains of rumen anaerobes and three strains of fiber-degradable bacteria were selected for single culture, mixed culture and sequence culture to study the relationship between the strains, and then the effects of carbon source composition on the interaction between rumen anaerobic fungi and fiber-degradable bacteria were determined. Combined with isotopic tracer technique, using 13 C labeled pure cellulose as the fermentation substrate of strain culture, the problem of fiber degradation was accurately traced, and the contribution and interaction between rumen anaerobes and bacteria in fiber degradation were evaluated and studied more accurately. The results showed that Clostridium faecalis, Enterococcus albicans, Neocallimastix and Cyllamyces had good fiber degradation and growth. The mixed culture of Clostridium berghei with Enterococcus and Neocallimastix could promote the fermentation, but the mixed culture of Clostridium Bayer and Cyllamyces had no obvious effect, and the mixed culture of Clostridium Bayer and Clostridium albicans could inhibit the fermentation, and the mixed culture of Clostridium albicans with Enterococcus, Neocallimastix and Cyllamyces could inhibit the fermentation, and the mixed culture of Enterococcus and Neocallimastix could promote the fermentation, and the mixed culture of Clostridium berberis and Clostridium albicans could inhibit the fermentation, inhibit the fermentation of Clostridium albicans and inhibit the fermentation. There was no obvious interaction between Cyllamyces and Enterococcus and Neocallimastix. After further sequence culture, it was found that there was an interaction between Clostridium monocytogenes, Enterococcus faecalis and Enterococcus albicans. If the mixed culture of fiber-degradable bacteria and anaerobes was promoted, it was anaerobes that promoted fiber-degradable bacteria, and if the mixed culture of fiber-degradable bacteria and anaerobes was inhibitory, it was the fiber-degradable bacteria that inhibited anaerobes. The promoting effect of mixed culture was mainly caused by the metabolites of the previous strain, but the increase of dry matter degradation rate was still due to the role of fiber binding sites. The reasons for the inhibition of bacterial protein concentration and gas production in mixed culture were the binding sites of metabolites to fiber, ammonia nitrogen concentration and TVFA, filter paper enzyme activity. Through the comparison of three different proportion of carbon sources, the results of microbial yield, degradation rate, VFA and NH3-N concentration were better when the ratio of crude material to concentrate was 7:3, which reflected that the combination was beneficial to the growth of microorganisms and the fermentation and utilization of substrate. By tracing the addition of 13 C isotopes to the substrate cellulose, it can be seen that the 13C abundance in VFA decreased sharply when the main route of cellulose in single culture was VFA, mixed culture. When the ratio of cellulose to starch is 7: 3, the main route of carbon is the ratio of carbon in VFA, gas.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S852.6

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