副干酪乳杆菌与芽孢杆菌属共培养种间关系对产细菌素的影响

为使芽孢杆菌属与副干酪乳杆菌(Lactobacillus paracasei)通过种间信息交流形成稳定的小生态环境,加大芽孢杆菌属的初始接种量,来探究L. paracasei HD1.7与其共培养的生态学关系。结果表明,将枯草芽孢杆菌(Bacillus subtilis)与L. paracasei HD1.7以5%：1%的初始接种比例共培养,L. paracasei HD1.7所产细菌素为其单培养的1.21倍,群体感应相关基因luxS,prcK和prcR分别上调表达3.14、4.98和5.41倍。同时,B. subtilis形成更多的芽孢以回避细菌素的攻击,芽孢形成相关基因spo0A,sigE,sigF和sigG分别上调2.37、2.71、3.15和2.56倍。此时,二者形成了一种协同合作的生态关系。冗余分析结果表明,共培养体系中与细菌素产生关系最为密切的是芽孢数量、培养时间以及B. subtilis活菌数。L. paracasei HD1.7与芽孢杆菌属之间存在不同的生态关系,有与之共培养后对L. paracasei HD1.7偏利的芽孢杆菌,也存在对其偏害的芽孢杆菌。

Interspecific Relationship of Lactobacillus paracasei Co-cultured with Bacillus sp. Affects Bacteriocin Production

To form a stable ecological environment through interspecific information exchange between Lactobacillus paracasei HD1.7 and Bacillus sp., the initial inoculation amount of Bacillus sp. was increased to study the ecological relationship of Lactobacillus paracasei co-cultured with Bacillus sp.. When Bacillus subtilis was co-cultured with L. paracasei HD1.7 at the initial inoculation ratio of 5%:1%, the bacteriocin produced by L. paracasei HD1.7 was 1.21 times that of monoculture. L. paracasei HD1.7 quorum sensing-related genes luxS, prcK, and prcR were upregulated (up to 3.14, 4.98 and 5.41 folds, respectively) while B. subtilis formed more spores to avoid the attack of bacteriocins. Expression levels of spo0A, sigE, sigF, and sigG, genes related to B. subtilis endospore formation, were correspondingly upregulated (up to 2.37, 2.71, 3.15 and 2.56 folds, respectively). At this time, a cooperative ecological relationship was formed between L. paracasei HD1.7 and Bacillus sp.. The redundancy analysis revealed that the number of spores, incubation time and B. subtilis viable counts were the most closely related to the production of bacteriocin. Different ecological relationships were found between L. paracasei HD1.7 and Bacillus sp., and some Bacillus are beneficial to L. paracasei HD1.7 and some are harmful to it.