Postbiotic is the term used to define the soluble factors, metabolic products, or byproducts released by live probiotic bacteria or after its lysis. The objective of this study was to carry out the chemical characterization of the postbiotic of Lacticaseibacillus rhamnosus LR-32 and to evaluate its in vitro effect on the development of the Streptococcus mutans biofilm. After the cultivation of the probiotic strain, the postbiotic was extracted by centrifuging the culture and filtering the supernatant. This postbiotic was characterized by using gas chromatography coupled with mass spectrometry (GC–MS), and then it was used to determine the growth inhibition of S. mutans in its planktonic form; additionally, its effects on the following parameters in 48 h biofilm were evaluated: viable bacteria, dry weight, and gene expression of glucosyltransferases and VicR gene. The control group consisted of the biofilm without any treatment. A paired t-test was performed for statistical analysis, with the p-value set at 5%. Seventeen compounds of various chemical classes were identified in the postbiotic, including sugars, amino acids, vitamins, and acids. The treatment with the postbiotic led to an inhibition of the growth of S. mutans in its planktonic form, as well as a decrease in the number of viable bacteria, reduction in dry weight, and a negative regulation of the gene expression of gtfB, gtfC, gtfD, and vicR in its biofilm state, compared with the nontreated group (p < 0.05). The postbiotic of L. rhamnosus impaired the development of S. mutans biofilm.

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乳杆菌后生元的化学特征及其对体外变形链球菌生物膜的影响

后生元是一个术语，用于定义活益生菌或其裂解后释放的可溶性因子、代谢产物或副产物。本研究的目的是对鼠李糖乳杆菌 LR-32 后生元进行化学表征，并评估其对变形链球菌生物膜发育的体外影响。益生菌菌株培养后，通过离心培养物并过滤上清液来提取后生元。使用气相色谱与质谱联用 (GC-MS) 对这种后生元进行了表征，然后用于测定浮游形式的变形链球菌的生长抑制作用；此外，还评估了其对48小时生物膜中以下参数的影响：活菌、干重、葡萄糖基转移酶和VicR基因的基因表达。对照组由未进行任何处理的生物膜组成。进行配对 t 检验进行统计分析，p 值设置为 5%。在后生元中鉴定出十七种不同化学类别的化合物，包括糖、氨基酸、维生素和酸。后生元处理导致浮游形式变形链球菌的生长受到抑制，活细菌数量减少，干重减少，并对 gtfB、gtfC 基因表达产生负调节、gtfD 和 vicR 处于生物膜状态，与未处理组相比 (p < 0.05)。鼠李糖乳杆菌的后生元损害了变形链球菌生物膜的发育。