一株贝莱斯芽孢杆菌的分离鉴定及其益生潜力评价

Isolation and identification of a Bacillus venezensis and its probiotic potential evaluation

贝莱斯芽孢杆菌(Bacillus velezensis)为芽孢杆菌属新型细菌。采用梯度稀释法及抑菌圈法进行菌株的分离和筛选,综合形态观察和16S rDNA序列比对对分离的菌株进行鉴定。通过高盐、胆盐、pH、模拟胃肠液、温度和抗生素等耐受性测定,结合体外抗氧化能力、抑菌活性以及溶血和动物饲喂试验,对分离菌株进行益生潜力评价。结果显示,从农家酱中分离出一株菌PJP10,初步鉴定为贝莱斯芽孢杆菌。该菌对金黄色葡萄球菌(Staphylococcus aureus)、肠炎沙门氏菌(Salmonella enteritidis)、副溶血弧菌(Vibrio parahaemolyticus)、青枯雷尔氏菌(Ralstonia solanacearum)和黑曲霉(Aspergillus niger)等拮抗效果显著,可以耐受8%NaCl、0.5%胆盐、100℃水浴、pH 2和模拟胃肠道的环境,对于头孢类、阿奇霉素等14种常用抗生素敏感。同时菌株PJP10无菌发酵液具有较好的抗氧化活性,对ABTS阳离子和DPPH自由基的清除率分别为(95.66±3.1)%和(44.84±2.2)%,Fe^(3+)还原能力和Fe^(2+)螯合率分别为(301.9±3.7)μmol/L和(76.88±2.2)%。此外,安全性试验表明无溶血圈,彭泽鲫饲喂未见异常。综上,贝莱斯芽孢杆菌PJP10具有良好的益生潜力,在食品行业中具有较高的应用价值。

Bacillus velezensis is a new species of the genus Bacillus. Separation and screening were carried out by gradient dilution method and the inhibition zone method, and the isolated strain was identified according to morphological observation and 16S rDNA sequence alignment. The tolerance to high salt, bile salt, simulated gastrointestinal fluid, temperature and antibiotics were tested, and antioxidant activity in vitro, antimicrobial susceptibility, the hemolysis and feeding test were examined to evaluate the probiotic potential of the strain. The results showed that the strain PJP10 was isolated from farmhouse fermented soybean paste and identified as B. velezensis. The PJP10 had significant inhibitory effect on various pathogens including Staphylococcus aureus, Salmonella enteritidis, Vibrio parahaemolyticus, Ralstonia solanacearum and Aspergillus niger. And it could tolerate 8%(mass fraction) NaCl, 0.5%(mass fraction) bile salt, 100 ℃, pH 2 and simulated gastrointestinal environment, and it was sensitive to 14 commonly used antibiotics such as cephalosporin and azithromycin. The fermentation broth of stain PJP10 exhibited good antioxidant activity with(95.66±3.1)% of ABTS cation radical scavenging rate,(44.84±2.2)% of DPPH free radical scavenging rate,(301.9±3.7) μmol/L of ferric ion reducing antioxidant power and(76.88±2.2)% of ferrous ion chelating rate. In addition, PJP10 showed no hemolysis activity and was safe to Carassius auratus var. Pengze. In conclusion, Bacillus velezensis PJP10 has good probiotic potential, indicating its application value in food industry.