Lactobacillus rhamnosus is a lactic acid bacterium with a diverse ecological habitat. We recently isolated a L. rhamnosus strain (LRB) from a healthy baby‐tooth that had naturally fallen out. We determined the whole genome sequence of LRB and found that the isolate is closely genetically related to an intestinal isolate, L. rhamnosus GG (ATCC 53103). However, the LRB genome had lost about a 75‐kb segment and undergone a genomic rearrangement. We assessed LRB's capacity to survive in the gut environment, at least temporarily. We found that LRB, like the intestinal isolate ATCC 53103, showed resistance to low pH but sensitive to bile salt. Surprisingly, we found that this oral isolate LRB showed strong antimicrobial activity against a variety of oral streptococci including Streptococcus mutans. The production of antimicrobial activity is dependent on media composition since some media supported the production while others did not. The production of antimicrobial activity is also dependent on growth temperature, with optimal production at 37°C. The antimicrobial activity was not restricted to streptococci, but effective against a variety of organisms, including ESKAPE pathogens.

中文翻译：

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鼠李糖乳杆菌 LRB 介导抑制口腔链球菌。

鼠李糖乳杆菌是一种具有多样化生态栖息地的乳酸菌。我们最近从一颗自然脱落的健康乳牙中分离出鼠李糖乳杆菌菌株 (LRB)。我们确定了 LRB 的全基因组序列，发现该分离物在遗传上与肠道分离物L. rhamnosus GG (ATCC 53103) 密切相关。然而，LRB 基因组丢失了大约 75 kb 的片段并进行了基因组重排。我们评估了 LRB 在肠道环境中的生存能力，至少是暂时的。我们发现 LRB 与肠道分离物 ATCC 53103 一样，表现出对低 pH 值的抵抗力，但对胆汁盐敏感。令人惊讶的是，我们发现这种口腔分离株 LRB 对多种口腔链球菌表现出很强的抗菌活性，包括变形链球菌。抗菌活性的产生取决于培养基成分，因为一些培养基支持生产，而另一些则不支持。抗菌活性的产生也取决于生长温度，最佳生产温度为 37°C。抗菌活性不仅限于链球菌，而且对多种生物有效，包括 ESKAPE 病原体。