藏羊源纤维素降解菌-沙福芽孢杆菌的分离鉴定及其生物学特性

为获得藏羊源纤维素降解益生菌，该试验采用纤维素刚果红培养基从藏羊瘤胃液中分离筛选出可降解纤维素的细菌，结合形态学、生理生化鉴定及16S rDNA序列分析对其进行种属鉴定，通过生长曲线的测定、抑菌试验和药敏试验研究该分离菌株的部分生物学特性。结果表明：筛选出一株纤维素刚果红培养基上呈粉红色、革兰氏染色呈阳性的菌株，命名为BS1-ql。分离菌株BS1-ql产芽孢，氧化酶试验、触酶试验呈阳性等生理生化特征符合芽孢杆菌属的特点，其16S rDNA序列与多株芽孢杆菌属菌株相似度达到96%以上，与沙福芽孢杆菌同源性达100%且处于同一最小分枝，明确该分离菌株是沙福芽孢杆菌。沙福芽孢杆菌BS1-ql生长迅速、接种2 h后进入对数生长期；对大肠杆菌、沙门氏菌、金黄色葡萄球菌、产气荚膜梭菌的抑菌圈均达8.96 nm以上，均有一定的抑制能力；对大多数常用抗生素呈现不同程度的敏感，对头孢他啶抗生素表现为耐药。结论：成功分离鉴定出一株藏羊源沙福芽孢杆菌，该分离菌株生物学特性良好，为藏羊源益生菌提供了候选菌株。

Isolation, Identification and Biological Characteristics of Cellulose-degrading Bacterium, Bacillus Shaffer, from Tibetan Sheep

In order to obtain cellulose-degrading probiotics from Tibetan sheep, cellulose Congo red medium was used to isolate and screen cellulose-degrading bacteria from the rumen fluid of Tibetan sheep Species identification was performed through combining morphological examination, physiological and biochemical identification, and 16 S rDNA sequence analysis. Some biological characteristics of the isolated strain were studied through the determination of growth curve, antibacterial test and drug susceptibility testing. The results showed that a pink and Gram-positive strain was screened out on cellulose Congo red medium (named BS1-ql). The isolated strain, BS1-ql, produced spores, and its physiological and biochemical characteristics were in line with the characteristics of Bacillus genus, such as positive oxidase test and catalase test. Its 16S rDNA sequence was more than 96% similar to that of multiple Bacillus strains, 100% homologous to Bacillus safensis and in the same smallest branch. It was confirmed that the isolated strain was Bacillus safensis. BS1-ql grew rapidly and entered the logarithmic phase 2 h after inoculation; the inhibition zones against Escherichia coli, Salmonella, Staphylococcus aureus and Clostridium perfringens were all above than 8.96 nm, indicating a certain degree of inhibition; BS1-ql was sensitive to most commonly used antibiotics to varying degrees, and resistant to ceftazidime antibiotics. Conclusion: A strain of Bacillus safensis from Tibetan sheep was successfully isolated and identified. The isolated strain has good biological characteristics and can be a candidate strain for probiotics from Tibetan sheep.