中文摘要：

采用体外拮抗试验方法,研究了2株分离自斜带石斑鱼幼鱼肠道的乳酸菌（MM1和MM4）的产酸能力及抑菌特性。结果表明,MM1产乳酸速度较快,且整个培养期间乳酸产量均显著高于MM4（P〈0.05）。MM1和MM4对革兰氏阴性细菌梅氏弧菌、哈维氏弧菌和革兰氏阳性细菌金黄色葡萄球菌均有强烈的抑制作用,但乳酸对2株乳酸菌的抑菌活性没有影响。过氧化氢酶显著降低了2株乳酸菌对梅氏弧菌和哈维氏弧菌的抑菌活性（P〈0.05）,但对金黄色葡萄球菌的抑菌活性影响较小,提示2株菌除能产生过氧化氢外,还能产生其它抑菌物质。2株乳酸菌产生的抑菌物质具有一定的热稳定性,对蛋白酶部分敏感,经3种蛋白酶（胃蛋白酶、胰蛋白酶和蛋白酶K）处理后,均保留70.0%以上的抑菌活性。因此,2株乳酸菌产生的抑菌物质具有热稳定性和蛋白酶部分敏感特性,且对革兰氏阴性菌和阳性菌均具有抑制效果,可推测为类细菌素物质。

英文摘要：

Lactic acid bacteria can produce inhibitory substances,such as lactic acid,hydrogen peroxide,bacteriocin and bacteriocin-like substance,and therefore can be used as probiotics to modulate the composition of gut microbiota and maintain the health of the host.The most rapid and experimentally simplest means for evaluating potential probiotic effects was to determine the inhibitory activity of the cell-free culture of lactic acid bacteria on pathogenic bacteria.In this study,two strains of lactic acid bacteria,MM1 and MM4,were isolated from the intestine of orange-spotted grouper（Epinephelus coioides）.Lactic acid production and antibacterial activity of two strains were studied in vitro.The results showed that MM1 exhibited more rapid production of lactic acid than MM4;and the amount of lactic acid produced by MM1 was significantly larger than that by MM4 in the whole incubation period（P 0.05）,but the pH values in the cultures of two strains were similar.MM1 and MM4 exhibited strong inhibitory activity against the pathogenic gram-negative Vibrio metschnikovi and V.harveyi,and gram-positive Staphylococcus aureus.However,lactic acid did not contribute to the inhibitory activity of the two strains.After 2 h of treatment with catalase,the inhibitory activity of MM1 and MM4 against V.metschnikovi and V.harveyi decreased significantly（P 0.05）,while the inhibitory activity against S.aureus was only affected slightly,suggesting,in addition to hydrogen peroxide,other inhibitory substances might be produced by the two strains.After 15min of heat treatments at 60℃,80℃ and 100℃,the residual inhibitory activity of MM1 and MM4 were above 86.0%,60.2% and 42.9%,respectively,indicating the inhibitory substances secreted by the two strains were heat stable.The residual inhibition activity of MM1 and MM4 were more than 70.0% after being treated with pepsin,trypsin and protease K,revealing that the inhibitory substances secreted by the two strains were partially sensitive to protease.Therefore,the inhibitory substance