香蕉植株上乳酸菌的分离鉴定、系统发育及抑菌特性分析

Separation, Identification, Phylogenetic Analysis and Antibacterial Activity of Lactobacillus from Banana Plants

为分析香蕉(Musa nana Lour.)植株上乳酸菌的多样性,扩大植物源乳酸菌菌种库,并为今后的青贮饲料发酵业和食品发酵工业等提供植物源乳酸菌,本研究运用经典乳酸菌筛选法与分子生物学相结合方法从香蕉植株上分离纯化乳酸菌,并对其进行生理生化实验、生长速率测定实验和产酸速率测定实验;根据以上实验结果选出代表性菌株,对其进行测序、同源性分析和系统发育树的构建;利用其发酵产物对大肠杆菌(Escherichia coli)、沙门菌(Salmonella)、枯草芽孢杆菌(Bacillus subtilis)和单核细胞性李斯特菌(Listeria monocytogenes)等食品中常见的致病菌进行抑菌实验。结果表明:从香蕉植株上6个部位共筛出44株乳酸菌疑似菌株,5株代表性菌株中有3株(WFr6-4、WSt6-4、WL7-3)为植物乳杆菌(Lactobacillus plantarum),1株(WFl5-3)为戊糖乳杆菌(Lactobacillus pentosus),1株(WR7-1)为酪黄肠球菌(Enterococcus casseliflavus)。代表菌株都能够明显抑制致病菌,其中WL7-3抑菌效果最好。由此可见,在香蕉植株上乳杆菌属为优势菌种,乳酸菌种类较为多样,而且抑菌效果较好。

In this research, we analyzed the diversity of Lactobacillus isolated from banana plants（Musa nana Lour.）, aiming to find new plant-derived strains of Lactobacillus for the silage and food fermentation industries in the future. The classical method was used for bacterial isolation and bacterial identification was performed by molecular biology techniques. In addition, the physiological and biochemical characteristics, growth rate and acid production rate of the isolates were evaluated and typical strains were selected for sequencing, 16 S rDNA sequence analysis and phylogenetic analysis. The bacteriostatic effects of the selected strains were investigated on the common foodborne pathogens Escherichia coli, Salmonella, Bacillus subtilis and Listeria monocytogenes. The results showed that 44 suspected strains were isolated from six parts of banana plants. Five typical strains were identified, namely 3 Lactobacillus plantarum（WFr6-4, WSt6-4 and WL7-3）, 1 Lactobacillus pentosus（WFl5-3） and 1 Enterococcus casseliflavus（WR7-1）. All the five strains showed significant antibacterial activity, with WL7-3 demonstrating the highest bacteriostatic effect. Thus, Lactobacillus was the dominant bacterium on banana plants, which had a strong bacteriostatic effect on all pathogens tested.