中文摘要：

通过测定6株乳酸菌及其混合发酵对3种革兰氏阳性菌和3种革兰氏阴性菌抑制作用，探究单一发酵及混合发酵对抑菌作用的影响。结果显示，6株不同乳酸菌及其混合发酵对3种革兰氏阳性菌和3种革兰氏阴性菌的抑制效果均不同。建立主成分分析模型，根据模型中累计贡献率达75．284％两个主成分，进行综合评分，可得乳酸菌混合发酵抑菌效果高于任一单菌株发酵，乳酸菌混合发酵表现出广谱抑菌性。通过排除乳酸及过氧化氢干扰，以及经pH6．0处理、121℃，20min热处理、蛋白酶K处理，进一步对乳酸菌及其混合发酵抑菌物质分析，可知除乳酸外，不同乳酸菌及其混合发酵的发酵产物中存在其他抑菌物质，且抑菌产物中过氧化氢浓度不足以产生抑菌效果。乳酸菌发酵抑菌物质在酸性条件下活性高，对热和蛋白质酶K敏感。

英文摘要：

The antibacterial effect of single fermentation and mixed fermentation were studied by measuring the inhibitory ability of 6 strains of Lactic acid bacteria and their mixed fermentation on three Gram-positive bacteria and three Gram-negative bacteria. Test results revealed, 6 strains of Lactic acid bacteria and their mixed fermentation had different effects on three Gram-positive bacteria and three Gram-negative bac- teria. Based on the cumulative contribution rate of 75.284% in the principal component analysis model, we can see that the antibacterial effect of mixed fermentation of Lactic acid bacteria was higher than any single strain. Mixed fermentation by 6 strains had a broad antibacterial spec- trum. Exclusion the organic acids and hydrogen peroxide, we has further analyzed antibacterial active ingredients of single fermentation and mixed fermentation by 6 strains at pH 6.0 , in 121 ℃ for 15 rain or treated by Proteinase K. We found that there were some antimicrobial substances in the fermentation product without lactic acid. The concentration of hydrogen peroxide in antimicrobial substances was not enough to produce antibacterial effect. The antibacterial substances had favorable stability in acid condition. And the antibacterial substances made by mixed fermentation have been sensitive to heat and protein enzyme K.