酰基高丝氨酸内酯提高小鼠肠道革兰氏阴性菌的分离培养效率

Acyl homoserine lactones facilitate the isolation and cultivation of Gram-negative bacteria from mouse intestine

摘要:

十二烷酰-l-高丝氨酸内酯(N-dodecanoyl-l-homoserine lactone, C12-HSL)是介导细菌群感效应的信号分子，调控细菌群体行为。本研究旨在探究C12-HSL对肠道微生物分离培养的影响，丰富小鼠肠道微生物可培养菌株资源的种类和数量。利用添加C12-HSL的培养基对小鼠肠道内容物进行菌株分离培养，共获得235个分离株，通过16S rRNA基因初步鉴定出54种菌，其中包含1个潜在新科，4个潜在新属，4个潜在新种；与实验室前期建立的小鼠肠道微生物菌株资源库mGMB比较，42个菌种为本研究的新增物种，丰富了菌库的物种多样性；统计分析发现，通过该方法分离获得的革兰氏阴性菌，特别是变形菌门的比例，显著高于未添加C12-HSL的普通分离培养方法。随后，对发现的一个新菌种进行培养实验表明，外源C12-HSL在20–200μmol/L浓度范围内对该菌种生长具有显著促进作用，而高浓度的C12-HSL则显著抑制该菌细胞密度。本研究证实了细菌群感效应分子在特定浓度范围内有助于肠道中革兰氏阴性菌的生长、分离和培养。尽管群感效应信号分子C12-HSL促进肠道菌株生长的机制还有待进一步探究，但本研究的发现为利用细菌群感效应信号分子靶向分离培养和调控肠道菌群提供了新思路。

Abstract:

N-dodecanoyl-l-homoserine lactone (C12-HSL) is a signaling molecule that mediates bacterial quorum sensing, regulating bacterial population behaviors. This study investigated the effects of C12-HSL on the isolation and cultivation of gut microbiota, with the goal of enriching the diversity and number of cultivable bacterial strains from the mouse gut microbiota. Using a culture medium supplemented with C12-HSL, we isolated and cultivated bacterial strains from mouse intestinal contents, obtaining a total of 235 isolates. Preliminary identification based on the 16S rRNA gene revealed 54 bacterial species, including 4 potential new species, 4 potential new genera and 1 potential new family. Compared with the previously established mouse gut microbial biobank (mGMB), this study newly identified 42 bacterial species, enhancing the diversity of the strain library. Statistical analysis showed that the proportion of Gram-negative bacteria, particularly those belonging to Proteobacteria, isolated by this method was significantly higher than that obtained by conventional isolation and cultivation methods without the addition of C12-HSL. Subsequent cultivation experiments with one of the newly discovered bacterial species indicated that exogenous C12-HSL at 20-200 μmol/L significantly promoted the growth of this species, while higher concentrations of C12-HSL significantly reduced the cell density of this bacterium. This work confirms that quorum sensing molecules, such as C12-HSL, can enhance the growth, isolation, and cultivation of Gram-negative bacteria in the gut within a specific concentration range. Although the mechanism by which C12-HSL promotes the growth of gut bacterial strains requires further investigation, the findings of this study provide new insights into the targeted isolation, cultivation, and regulation of gut microbiota using bacterial quorum sensing signal molecules.