植物乳植杆菌P-8与拟杆菌之间的代谢调控及其物种特异性互作

Metabolic regulation and species-specific interactions between Lactiplantibacillus plantarum P-8 and Bacteroides

摘要:

背景 益生菌与肠道核心菌群(如拟杆菌)之间复杂的相互作用，是其发挥益生功能的重要前提。然而，其具体的微观互作机制及物种特异性代谢交互模式仍有待阐明。目的 通过构建植物乳植杆菌(Lactiplantibacillus plantarum) P-8与溶木聚糖拟杆菌(Bacteroides xylanisolvens)、单形拟杆菌(Bacteroides uniformis)、埃氏拟杆菌(Bacteroides eggerthii)的体外共培养模型，分析不同时间点的群落动态和代谢物变化，从而探究它们之间是否存在物种特异性的互作模式以及潜在的跨物种代谢互补机制。方法 建立菌株P-8与3株拟杆菌的双菌共培养体系，于0、12、24、48 h测定生长曲线，结合宏基因组学与非靶向代谢组学分析群落结构与代谢互作特征。结果 菌株P-8与3株拟杆菌均能稳定共存，但互作模式呈现明显的物种差异。其中，与B. uniformis和B. eggerthii的共培养组表现出明显的“超产效应”，即共培养体系生物量显著高于单菌最大值(P<0.05)，48 h总生物量分别为单菌对照组的1.35倍和1.90倍；而B. xylanisolvens组中拟杆菌作为优势菌株(相对丰度>90.00%)，其共培养组的生长情况及代谢特征与B. xylanisolvens单菌状态相似，而在B. uniformis和B. eggerthii的共培养组中，则观测到苯丙氨酸在24 h被消耗、并于48 h转化为苯乳酸的现象。这一代谢转化过程提示了跨物种代谢互补的存在。结论 菌株P-8与拟杆菌之间能够建立稳定的共生关系，但其功能输出依赖于共生的特定拟杆菌种类。这种代谢调控不仅促进了益生菌次级代谢产物的合成，也为理解益生菌在不同肠道环境中的定殖差异和个体化功效提供了新的视角。

Abstract:

Background The interactions between probiotics and core taxa such as Bacteroides in the gut microbiota are crucial prerequisites for their functional efficacy. However, the specific microscopic interaction mechanisms and species-specific metabolic cross-feeding patterns remain to be elucidated.Objective This study established in vitro co-culture models of Lactiplantibacillus plantarum P-8 with three Bacteroides strains (B. xylanisolvens, B. uniformis, and B. eggerthii) to analyze community evolution and metabolic profiles across different time points, aiming to elucidate the species-specific interactions and cross-species metabolic complementarity.Methods Dual-strain co-culture systems consisting of P-8 and either B. xylanisolvens, B. uniformis, or B. eggerthii were constructed with the modified GAM medium. OD₆₀₀ values were recorded at the time points of 0, 12, 24, and 48 h for establishment of growth curves. Metagenomic and non-targeted metabolomic analyses were performed to characterize the community structures and metabolic interaction features at the time points of 24 h and 48 h.Results P-8 established stable coexistence with all the three Bacteroides strains, although the interaction patterns exhibited significant species-specific differences. Specifically, the co-culture groups involving B. uniformis and B. eggerthii demonstrated a pronounced over-yielding effect, with the total biomass at 48 h being significantly higher than that of either monoculture (P<0.05). In the co-culture system with B. xylanisolvens, the Bacteroides strain remained the dominant taxon throughout cultivation, accounting for more than 90% of the community abundance, and the metabolic profile of the co-culture closely resembled that of the B. xylanisolvens monoculture, characterized by the sustained accumulation of organic acids such as succinate. Conversely, in the co-culture of P-8 with B. uniformis or B. eggerthii, distinct metabolic transition was observed: phenylalanine was consumed within 24 h and subsequently converted into phenyllactic acid within 48 h. This temporal metabolic evolution highlighted the existence of cross-species metabolic complementarity between P-8 and specific Bacteroides species.Conclusion P-8 maintains robust symbiotic relationships with Bacteroides strains. However, its functional output is highly dependent on the co-existing Bacteroides species. This metabolic complementarity enhances the synthesis of secondary metabolites and provides a theoretical basis for understanding the individualized efficacy and colonization differences of probiotics in diverse gut environments.