抗食源性致病菌益生菌的筛选及其抑菌活性评价

采用交叉划线法、径向划线法、琼脂扩散法及液体共培养法评价各益生菌菌株及其代谢产物对4 株具代表性食源性致病菌的抑菌作用，并从20?株益生菌中筛选出同时对单核细胞性李斯特菌和金黄色葡萄球菌（革兰氏阳性致病菌）及大肠杆菌和鼠伤寒沙门菌（革兰氏阴性致病菌）具有良好抑菌活性的益生菌菌株。将筛选出的益生菌添加到羟丙基纤维素、丙三醇及魔芋粉的高分子复合材料中制备生物活性抑菌膜，并对抑菌膜中益生菌的存活情况及抑菌膜的抗菌效果进行评价。交叉划线法及径向划线法实验结果一致：乳杆菌属和肠球菌属的菌株，特别是Lactobacillus paracasei CICC 20241菌株对4?株目标致病菌均具有较高的抗菌活性；琼脂扩散法实验表明：L. paracasei CICC 20241菌株的培养液、上清液和菌悬液均具有较好的抑菌效果；液体共培养法实验表明：乳酸菌L. paracasei CICC 20241先于致病菌接种时表现出更高的生长活性和拮抗活性。此外，本实验制备的抑菌膜是L. paracasei CICC 20241菌株的良好载体，适宜该菌株的生长存活并对目标致病菌表现出持续的抗菌活性，对于开发鲜食食品的包装材料具有较大的应用潜力。

Screening and Evaluation of Probiotics for Antimicrobial Activity against Foodborne Pathogenic Bacteria

Cross streak, radial streak, agar diffusion and co-culture methods were used to assess the antimicrobial activity of various probiotics and their metabolites against four representative foodborne pathogenic bacteria. The probiotic strains with great antibacterial activity against both Gram-positive pathogens (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative pathogens (Escherichia coli and Salmonella typhimurium) were screened out. They were incorporated into polymeric materials (hydroxypropyl cellulose, glycerol and konjac flour) to develop bacteriostatic films, and the probiotic viability and the antimicrobial effects of films were measured. The consistent results obtained from cross streak and radial streak tests showed that Lactobacillus and Enterococcus especially Lactobacillus paracasei CICC 20241 exhibited high antibacterial activity against four target pathogens; the agar diffusion test showed that the lactic acid bacteria culture (LC), cell-free supernatant (CFS), and bacterial cells (BC) of L. paracasei CICC 20241 all had great antibacterial effect, and the co-culture test showed that L. paracasei CICC 20241 exhibited higher growth activity and antagonistic activity when inoculated earlier than the pathogens. In addition, the bacteriostatic film prepared in this experiment was a good carrier for L. paracasei CICC 20241, which was suitable for the survival of the Lactobacillus strain and exhibited continuous antibacterial activity against the target pathogens. The Lactobacillus film may have a great application potential for the development of packaging materials for fresh foods.