乳酸菌LE-Z的筛选鉴定及其益生性的初步评价

Screening and identification of Lactobacillus LE-Z and preliminary evaluation of its probiotics

为了筛选猪源肠道潜在益生菌,试验先对健康成华猪粪便中的微生物进行分离纯化,通过体外抑菌试验筛选1株对致病菌有抑制作用的菌株,对该菌株进行形态观察、生化试验、16S rRNA PCR扩增及测序,并对测得的序列进行遗传进化分析,然后再对分离菌株进行耐酸、耐猪胆盐试验及药敏试验分析。结果表明:分离纯化得到1株对大肠杆菌、金黄色葡萄球菌、猪链球菌有抑制作用的肠球菌,经生化鉴定和PCR鉴定为耐久肠球菌(Enterococcus durans),命名为LE-Z。该菌株在pH值2.0,4.0的环境中培养5 h存活率分别达到39.64%和58.91%,在猪胆盐浓度为0.25%、0.5%的环境中培养2 h存活率分别达到56.73%和12.82%。菌株LE-Z对大部分抗生素敏感,但对丁胺卡那、头孢他啶、庆大霉素、卡那霉素和新霉素5种抗生素耐药。说明菌株LE-Z具有一定的抗药性,在一定程度上能够耐受低pH值和高胆盐浓度的环境,可作为益生菌候选株进行后续试验。

In order to screen potential probiotics from pig intestines, the microbes in the feces of healthy Chenghua pigs were isolated and purified. According to in vitro bacteriostatic test, a strain with antibacterial effect was selected. Morphological observation, biochemical assays, 16 S rRNA PCR amplification and sequencing were carried out on the strain, and the measured sequence was analyzed by genetic evolutionary. Then acid and pig bile salt tolerance tests and drug sensitivity tests were carried out. The results showed that a strain of Enterococcus, which had inhibitory effect on Escherichia coli, Staphylococcus aureus and Streptococcus suis, was isolated and identified as Enterococcus durans by biochemical identification and PCR, named LE-Z. The survival rate of the strain reached 39.64% and 58.91% in the pH value 2.0 and 4.0 environment for 5 hours, respectively, and 56.73% and 12.82% in the environment with pig bile salt concentration of 0.25% and 0.5% for 2 hours. LE-Z was sensitive to most antibiotics, but resistant to five kinds of antibiotics of amikacin, ceftazidime, gentamicin, kanamycin and neomycin. These results indicated that strain LE-Z had certain drug resistance and could tolerate the environment of low pH value and high pig bile salt concentration to a certain extent. It can be used as a probiotic candidate for subsequent tests.