一株纤维降解菌的鉴定及其对酒糟固态发酵效果的研究

Identification of one fiber degrading bacterium and its effect on solid fermentation of distillers’grains

为鉴定本实验室前期筛选的一株纤维降解菌,并优化其发酵白酒糟的条件,通过16S rRNA序列分析并结合菌株形态和部分生理生化方法进行菌株鉴定,随后利用该菌进行白酒糟发酵试验。首先采用单因素试验设计,然后根据发酵后白酒糟营养成分变化,确定用于正交试验的各因素水平,在此基础上进行四因素三水平的正交试验设计确定最适发酵条件,最后比较发酵前后营养成分、酒糟结构以及体外瘤胃发酵参数的变化。结果表明:1)菌株T5鉴定为Cohnella xylanilytica,其发酵白酒糟的最适条件为:发酵温度33℃,发酵时间5d,种子液添加量25%,料水比1∶1.50。2)最适条件下,对照组和T5发酵组的粗蛋白质、真蛋白质、粗纤维、中性洗涤纤维、酸性洗涤纤维和粗灰分含量差异显著(P<0.05)。与对照组相比,T5发酵组粗蛋白质和真蛋白质质量分数分别增加了19.68%和30.38%,而中性洗涤纤维和酸性洗涤纤维分别降解了31.68%和27.69%。T5发酵组的扫描电镜结果显示酒糟结构松散,表面出现大量孔洞。3)人工瘤胃体外产气法结果表明,T5发酵组的氨态氮质量浓度、各挥发性脂肪酸质量浓度以及干物质降解率均显著高于对照组(P<0.05),而甲烷产量显著低于对照组(P<0.05)。综上,分离获得的纤维降解菌可用于降解糟粕类饲料纤维,有利于改善低质粗饲料营养价值,该菌可以作为饲料资源开发利用的候选菌株。

To identify one fiber degrading bacterium screened earlier in our laboratory and optimize the fermentation conditions of distiller’s grains,this strain was identified based on the 16S rRNA sequence analysis,strain morphology and partial physiological and biochemical results and fermentation experiment was subsequently carried out.Firstly,single factor experiment design was used.Then,according to the nutrient change after fermenting distiller’s grains,the level of various factors for the orthogonal experiment were determined.Four factors and three levels orthogonal experiment design were used to determine the optimal conditions;Finally,the nutrient composition,distiller’s grains structure and rumen fermentation parameters were compared before and after fermentation.The results showed that:1)The strain T5 was identified as Cohnella xylanilytica.The optimal fermentation factors of strain T5 were fermentation temperature 33℃,fermentation time 5 d,the additive amount 25% and the ratio of material to water 1∶1.50.2)Under the optimum conditions,there were significant differences in contents of crude protein,true protein,crude fiber,neutral detergent fiber,acid detergent fiber and ash between control group and experimental group(P<0.05).Compared with the control group,the crude protein and true protein of the experimental group respectively increased by19.68% and 30.38% while the neutral detergent fiber and acid detergent fiber were respectively degraded by 31.68% and 27.69%.The scanning electron microscope results of T5 fermentation group showed that the structure of distiller’s grains was loose and holes appeared.3)The results of artificial rumen invitro gas production showed that the ammonia nitrogen concentration,volatile fatty acid concentration and dry matter digestibility in the T5 fermentation group were significantly higher than those in the control group(P<0.05),while methane production was significantly lower than that of control group(P<0.05).In conclusion,the isolated fiber degrading bacteria can be used to degrade the fiber of distillers’grains,which is conducive to improve the nutritional value of low-quality roughage.The strain T5 can be used as a candidate strain for the development and utilization of feed resources.