抗鼠伤寒沙门氏菌的乳酸菌细菌素生物学特性及其抑菌机制初步研究

Preliminary study on biological characteristics and inhibitory mechanism of Lactobacillus bacteriocins against Salmonella typhimurium

试验旨在研究拮抗鼠伤寒沙门氏菌的新型乳酸菌细菌素生物学特性及其抑菌机制。采用全基因组测序分析产细菌素的乳酸菌基因组信息,琼脂扩散法和透析法测定细菌素抑菌活性及分子量范围,有机酸、过氧化氢排除试验和蛋白酶敏感试验确定细菌素性质,通过设置pH值与温度梯度测定乳酸菌生长曲线与细菌素抑菌曲线,研究细菌素生物学特性,扫描电子显微镜观察初步探索细菌素抑菌机制。结果显示,试验筛选出的1株具有抑菌活性的乳酸菌PG-9,经分子生物学鉴定为发酵黏液乳杆菌。全基因组大小为1985177 bp,包含1947个编码基因。其产细菌素PG-9B对鼠伤寒沙门氏菌抑菌活性良好,分子量小于1 kDa,排除有机酸、过氧化氢影响后发现其对多种蛋白酶敏感,在pH值3.0~7.0、-20~121℃范围内均保留了较高的抑菌活性。扫描电镜显示,发酵黏液乳杆菌细菌素PG-9B通过破坏鼠伤寒沙门氏菌细胞表面形态而抑制和杀死细胞。研究表明,发酵黏液乳杆菌细菌素PG-9B具有良好的生物学特性和抑菌活性,在饲料工业中可作为潜在的替抗添加剂防治鼠伤寒沙门氏菌。

The aim of this experiment was to study the biological characteristics and inhibitory mechanism of a novel Lactobacillus bacteriocin against Salmonella typhimurium.Whole genome sequencing was used to analyze the genomic information of bacteriocin-producing lactic acid bacteria,agar diffusion and dialysis methods were used to determine the bacteriocin inhibitory activity and molecular weight range,organic acid,hydrogen peroxide exclusion test and protease sensitivity test were used to determine the nature of bacteriocin,and the biological properties of bacteriocin were investigated by setting up pH value and temperature gradients,determining the growth curves and bacteriocin inhibitory curves of lactic acid bacteria,and the preliminary exploration of bacteriocin inhibitory mechanism was carried out by scanning electron microscope observation.Scanning electron microscope observation was used to explore the mechanism of bacteriocin inhibition.The results showed that a strain of Lactobacillus PG-9 with bacteriocin inhibitory activity was identified as Limosilactobacillus fermentum by molecular biology,with a full genome size of 1985177 bp,containing 1947 coding genes.The bacteriocin PG-9B it produced had good bacteriostatic activity against Salmonella typhimurium,with an estimated molecular weight of less than 1 kDa.After excluding the effects of organic acids and hydrogen peroxide,it was found to be sensitive to various proteases,in the range of pH 3.0~7.0 and-20~121℃,high antibacterial activity was retained.Scanning electron microscopy showed that the Limosilactobacillus fermentum citriodora bacteriocin PG-9B inhibits and kills cells by disrupting the cell surface morphology of Salmonella typhimurium.The study indicates that the favorable biological properties of Limosilactobacillus fermentum bacteriocin PG-9B can be used as a potential alternative antioxidant additive for the control of Salmonella typhimurium in the feed industry.