酸马奶提取植物乳杆菌DSM20174细菌素的理化特性研究

为研究从酸马奶中提取的植物乳杆菌DSM20174细菌素的理化特性,本试验提纯植物乳杆菌DSM20174细菌素,经过硫酸铵沉淀、透析后得到细菌素粗提液,再利用SephadexG-100凝胶柱层析进行纯化后,细菌素的比活力明显增加,达到154.70 AU/mL,得率为43.5%.采用牛津杯法测定纯化的植物乳杆菌DSM20174细菌素在3种不同方式处理下对牛源野生致病性大肠杆菌O78抑菌效果的影响.结果显示:①植物乳杆菌DSM20174细菌素在5组温度处理下,随着温度的升高抑菌作用降低,各组抑菌作用差异显著(P<0.05).即使121 ℃处理30 min后,抑菌直径仍达14.90 mm.②植物乳杆菌DSM20174细菌素在pH 2.0~12.0由低到高的11组酸碱处理下,pH越大抑菌直径越小,且除了pH 9.0和pH 10.0之间差异不显著(P>0.05)外,其余各组抑菌作用均差异显著(P<0.05). ③植物乳杆菌DSM20174细菌素经胰蛋白酶、胃蛋白酶、木瓜蛋白酶3种酶处理后抑菌直径变化明显,处理前后抑菌作用均差异显著(P<0.05).结果表明植物乳杆菌DSM20174细菌素是较好的抑菌活性物质,但不是热稳定性物质;具有较广泛的pH适用范围,且pH越小时其抑菌活性越强,在最适生长pH时抑菌活性有所增强;不是蛋白酶稳定性物质.     

牛源致病性Escherichia coli O8对小鼠小肠结构及免疫相关细胞的影响

为研究小鼠感染牛源致病性大肠杆菌(Escherichia coli)O8后小肠结构和免疫相关细胞的变化,用试验观察小鼠感染后的患病症状,采集小鼠小肠组织样品,HE和PAS染色后观察其病理切片,测定小肠结构中肠绒毛长度、隐窝深度、肠绒毛长度/隐窝深度(V/C)值、肌层厚度及免疫相关细胞肠上皮淋巴细胞和杯状细胞的数量。结果表明,小鼠感染牛源致病性E.coli O88~12h出现患病症状;24h出现明显患病症状,个别小鼠死亡;36~48h小鼠患病症状更加严重,死亡小鼠增多;72h不再出现死亡小鼠,未死亡小鼠精神状态和行动能力全面好转。小鼠感染牛源致病性E.coli O8后,小肠肠绒毛长度、V/C值、肌层厚度、肠上皮淋巴细胞和杯状细胞数量先减少后增多,隐窝深度先增大后减小。小鼠感染牛源致病性E.coli O8后0~72h小肠各指标出现规律性变化,其中,36h小鼠感染最严重,72h开始恢复。     

Study on Physicochemical Properties of Lactobacillus plantarum DSM20174 Bacteriocin from Koumiss

To study the physicochemical properties extracted from koumiss of Lactobacillus plantarum DSM20174 bacteriocin,we purified the Lactobacillus plantarum DSM20174 bacteriocins and got the bacteriocin crude extractions after ammonium sulfate precipitation and dialysis.After purification with Sephadex G-100 gel column chromatography,bacteriocin specific activity apparently increased,reaching 154.70 AU/mL,yield was 43.5%.We detected the effects of purified Lactobacillus plantarum DSM20174 bacteriocin on bacteriostatic action of wild bovine pathogenic E.coli O78 by Oxford cup method under 3 different treatments.The results showed that:①In five groups of temperature treatments,the bacteriostatic action decreased with the increase of temperature,bacteriostatic actions of all groups were significantly different (P<0.05).Even after treatment at 121 ℃ 30 min,antimicrobial diameter was 14.90 mm.② After Lactobacillus plantarum DSM20174 bacteriocin were treated with pH 2.0 to pH 12.0,the higher of pH,the smaller of antibacterial diameter.The inhibitory effect of groups were significantly different (P<0.05) except pH 9.0 and pH 10.0.③Lactobacillus plantarum DSM20174 bacteriocins were treated by trypsin,pepsin and papain,antibacterial diameter apparently changed,bacteriostatic action was significantly different (P<0.05) before and after treatment.The results suggested that Lactobacillus plantarum DSM20174 bacteriocins were better antibacterial substances,but not thermal stability substances.It had a relatively wide pH range,and the smaller of pH,the stronger of its antibacterial activity,the antibacterial activity had been enhanced at optimum growth pH.It was not protease stability substances.