产细菌素弯曲乳杆菌的分离鉴定及细菌素特性初步研究
Separation and identification of bacteriocin-producing Lactobacillus curvatus and characterization of its bacteriocin
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摘要: 从西班牙传统色拉米香肠中分离到一株产细菌素菌株RX-6,其发酵液在排除有机酸、过氧化氢及菌体细胞干扰后,抑菌活性基本无变化;经硫酸铵盐析及透析处理后,抑菌活性明显增强;蛋白酶K处理后,抑菌活性消失,表明起抑菌作用的是蛋白类物质。通过菌体形态观察、生理生化特征实验、16SrRNA序列比对及系统发育分析,鉴定菌株RX-6为弯曲乳杆菌(Lactobacillus curvatus)。抑菌特性研究结果显示该菌株所产细菌素具有很好的热稳定性和酸碱耐受性,在121℃20min的高温处理后仍能保持一定活性,活性pH范围为310;使用安全性高,胃蛋白酶和胰蛋白酶可将其完全分解,而酸性蛋白酶可将其部分分解;抑菌谱较广,对受试的7株李斯特菌(Listeria spp.)、3株金黄色葡萄球菌(Staphylococcus aereu)、1株大肠杆菌(Escherichia coli)及1株假单胞菌(Pseudomonas spp.)等都有明显抑制作用,显示出作为天然食品生物防腐剂的巨大应用潜力。Abstract: Bacteriocin-producing stain RX-6 was isolated from Spanish traditional Salami sausages. After eliminating some interference factors such as the organic acids, hydrogen peroxides and strain cells, the antimicrobial activity of the fermentation broth of strain RX-6 remained the same. By ammonium sulphate precipitation and dialysis, the activity was significantly enhanced. However, the substance was inactivated when treated with proteinase K. These results indicated the nature of antibacterial substance produced by strain RX-6 was protein. Based on morphological, physiological and biochemical characteristics, 16S rRNA gene sequence and phylogenic analysis, strain RX-6 was identified as Lactobacillus curvatus. Results obtained from characteristics analysis of the bacteriocin produced by strain RX-6 showed this bacteriocin still remained activated after the heat treatment at 121℃ for 20min and the pH activity range was 3 to 10, which indicated that it had strong heat stability and acid-base tolerance. Also, the bacteriocin could be inactivated by pepsin and trypsin, and partially inactivated by acid proteinase, which suggested that its use safety was very high. In addition, the bacteriocin had a broad inhibitory spectrum and could show inhibitory activity against Listeria spp., Staphylococcus spp., Pseudomonas spp. and Escherichia coli, which indicated that the bacteriocin had a potential application as natural food bio-preservatives in food industry.