Yin Haichang, Du Zunhe, Jiang Xinjie, Zhou Yao, Jin Zhenhua, Cong Feng
College of Life Science and Agriculture Forestry, Qiqihar University, Qiqihar, Heilongjiang 161006, China; Guangdong Laboratory Animals Monitoring Institute, 2.Guangdong, Guangzhou 510663, China.
College of Life Science and Agriculture Forestry, Qiqihar University, Qiqihar, Heilongjiang 161006, China.
Poult Sci. 2025 Apr 1;104(6):105119. doi: 10.1016/j.psj.2025.105119.
Avian pathogenic Escherichia coli can cause high morbidity, mortality, and serious economic losses to the global poultry industry. Lactic acid bacteria inhibit the growth of many pathogens, including E. coli, but the underlying mechanism remains unclear. In this study, we investigated the effect of the cell-free supernatant of Ligilactobacillus animalis 2020MB isolated from the intestinal tract of chickens on specific pathogen-free chickens infected with E. coli. The cell-free supernatant-induced inhibition of E. coli infection was determined through clinical symptom observation, pathological analysis, and qPCR. Protease and heat treatments did not affect the antibacterial activity of cell-free supernatant, suggesting that an organic acid was the antibacterial substance. Liquid chromatography-mass spectrometry and non-targeted metabolomics identified antibacterial activity for eight L. animalis 2020MB cell-free supernatant metabolites, including butyric, valeric, and succinic acids. The inhibitory activity of butyric acid was quantified by determining the minimal inhibitory concentration. Scanning electron microscopy, laser confocal microscopy, and proteomic analysis revealed that butyric acid altered the morphology and impaired the cell envelope integrity of target bacteria, leading to leakage of intracellular contents. BamA was identified as the membrane protein target for butyric acid. The findings reveal the molecular mechanism of action of L. animalis 2020MB in the chicken intestine against E. coli.
禽致病性大肠杆菌可导致全球家禽业高发病率、高死亡率和严重的经济损失。乳酸菌可抑制包括大肠杆菌在内的多种病原体的生长，但其潜在机制尚不清楚。在本研究中，我们调查了从鸡肠道分离的动物源 Ligilactobacillus 2020MB 的无细胞上清液对感染大肠杆菌的无特定病原体鸡的影响。通过临床症状观察、病理分析和定量聚合酶链反应（qPCR）确定无细胞上清液对大肠杆菌感染的抑制作用。蛋白酶和热处理不影响无细胞上清液的抗菌活性，表明有机酸是抗菌物质。液相色谱 - 质谱联用和非靶向代谢组学鉴定出动物源 Ligilactobacillus 2020MB 无细胞上清液的八种代谢产物具有抗菌活性，包括丁酸、戊酸和琥珀酸。通过测定最小抑菌浓度对丁酸的抑制活性进行了定量。扫描电子显微镜、激光共聚焦显微镜和蛋白质组学分析表明，丁酸改变了靶细菌的形态并损害了其细胞膜完整性，导致细胞内容物泄漏。BamA 被确定为丁酸的膜蛋白靶点。这些发现揭示了动物源 Ligilactobacillus 2020MB 在鸡肠道中对抗大肠杆菌的分子作用机制。
