以干酪乳杆菌发酵荔枝汁为研究对象，在人工胃液、人工肠液环境下对干酪乳杆菌的存活性能进行研究；同时，采用琼脂扩散法，研究其对六种常见食源性致病菌（肠炎沙门氏菌、宋氏志贺氏菌、大肠埃希氏菌O157:H7、单增李斯特氏菌、金黄色葡萄球菌和阪崎肠杆菌）的抑菌性，以及探究酸和酶等因素对发酵液抑菌性的影响。结果表明：在模拟胃肠消化中，干酪乳杆菌在pH 1.5、pH 2.0、pH 3.0和pH 4.0的人工胃液中培养4 h后，活菌数分别达到了260 CFU/mL、8.63×107 CFU/mL、9.57×107 CFU/mL和1.15×108 CFU/mL；在人工肠液中消化12 h后，活菌数均在107 CFU/mL以上。在抑菌试验中，经去酸、去过氧化氢和酶解等不同处理的发酵液对肠炎沙门氏菌等五种常见食源性致病菌具有明显的抑制效果，而对阪崎肠杆菌均未表现出抑制作用，其中胞外多糖、H2O2和蛋白肽类物质对五种常见的致病菌是主要的抑菌物质。研究结果为干酪乳杆菌发酵荔枝汁能否在胃肠道中发挥有益作用提供体外实验的理论依据以及在当地食品工业的开发应用提供科学依据。

The survival of Lactobacillus casei in its fermented lychee juice was investigated in an artificial gastric juice and artificial intestinal juice model. At the same time, the antimicrobial activities of the fermented juice against six common foodborne pathogens (Salmonella, Shigella sonnei, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Enterobacter sakazakii) were examined using the agar diffusion method, considering the effects of acids and enzymes. The results showed that in the simulated gastrointestinal digestion model, the viable counts of Lactobacillus casei were 260, 8.63×107, 9.57×107 and 1.15×108 CFU/mL, respectively, after a 4-h incubation in an artificial gastric juice at pH 1.5, 2.0, 3.0 or 4.0, while above 107 CFU/mL after a 12-h digestion in the artificial intestinal juice. In terms of antimicrobial activity, the fermentation broths subjected to different treatments such as deacidification, hydrogen peroxide removal and enzymatic hydrolysis exhibited significant inhibitory effects on five common foodborne pathogenic bacteria including Salmonella enteritidis, except for Enterobacter sakazakii. Exopolysaccharide, H2O2 and protein peptides were the main antimicrobial substances against five common pathogenic bacteria. These results will lay a theoretical foundation for in vitro experiments on whether Lactobacillus casei fermented lychee juice could offer beneficial effects in the gastrointestinal tract and provides a scientific basis for local food industrial development and application.

广东省科技计划项目（2017A030303038）；广东省科技计划项目（2017B020207005）