苏云金芽胞杆菌BRC-ZLL5类细菌素的抑菌谱和理化特性

Antibacterial spectrum and physiochemical property of bacteriocin-like inhibitory substances from Bacillus thuringiensis BRC-ZLL5

为提升苏云金芽胞杆菌(Bacillus thuringiensis,简称Bt)生物农药产品附加值,通过对其发酵上清液提取细菌素,进一步研究Bt菌株BRC-ZLL5类细菌素(Bacteriocin-like inhibitory substa nces,BLIS)的抑菌谱和理化特性.结果显示:BRC-ZLL5类细菌素对李斯特菌、铜绿假单胞杆菌、粪链球菌具有活性,对4种肠道益生菌及自身无抗菌活性;抑菌活性动态监测表明其活性集中于6-18 h,在12 h达到最大值;分子量(Mr)小于1.43×104;具有较广的pH耐受范围(pH 3-9)和较强的耐热能力(50-90℃时活性极显著提高;121℃高压灭菌15 min仍保持32%活性);脂肪酶Ⅱ可极显著提高其活性(P<0.01),蛋白酶K、α胰凝乳蛋白酶Ⅶ、α胰凝乳蛋白酶Ⅱ使其活性消失(P<0.01).BRC-ZLL5类细菌素可望用于进一步开发,本研究为高效利用Bt发酵上清液提供了依据.

To add value to Bacillus thuringiensis（Bt） products, extraction of bacteriocins from Bt fermentation supernatants is needed. This paper aimed to study the extraction methods and the property of Bt bacteriocin-like inhibitory substances（BLIS）. In this study, antibacterial spectrum and physiochemical property of Bt BRC-ZLL5 BLIS were investigated using Listeria monocytogenes（Lm） as one of the indicator strains. The results showed that BRC-ZLL5 BLIS were active against Listeria, Pseudomonas aeruginosa and Streptococcus faecalis, but not against itself and 4 probiotics. The activity of BRC-ZLL5 BLIS against Lm 100525 existed for 6-18 h after incubation, peaking at 12 h after incubation. The molecular weight（Mr） of BRCZLL5 BLIS was less than 1.43 × 104. The BRC-ZLL5 BLIS were pH stable（pH 3-9） and heat-resistant： compared with that at 4 °C, the activity of BRC-ZLL5 BLIS was significantly increased after treatment at 50-90 °C for 30 min; it retained 32% activity after treatment at 121 °C for 15 min. The antibacterial activity of BRC-ZLL5 BLIS was increased with addition of lipase II（P 0.01） while completely lost after treatment with proteinase K, α-chymotrypsin VII and α-chymotrypsin II（P 0.01）. This study provides a model for utilization of Bt fermentation supernatants with high efficiency.