Zhang Wenping, Luo Qingqing, Zhang Yiyin, Fan Xinghui, Ye Tian, Mishra Sandhya, Bhatt Pankaj, Zhang Lianhui, Chen Shaohua
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China.
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China.
Microorganisms. 2020 Jul 23;8(8):1100. doi: 10.3390/microorganisms8081100.
Quorum sensing (QS) is a cell density-dependent mechanism that regulates the expression of specific genes in microbial cells. Quorum quenching (QQ) is a promising strategy for attenuating pathogenicity by interfering with the QS system of pathogens. -Acyl-homoserine lactones (AHLs) act as signaling molecules in many Gram-negative bacterial pathogens and have received wide attention. In this study, a novel, efficient AHL-degrading bacterium, sp. strain XN-10, was isolated from agricultural contaminated soil and evaluated for its degradation efficiency and potential use against QS-mediated pathogens. Strain XN-10 could effectively degrade -(3-oxohexanoyl)-L-homoserine lactone (OHHL), -hexanoyl-L-homoserine lactone (C6HSL), -(3-oxododecanoyl)-L-homoserine lactone (3OC12HSL), and -(3-oxooctanoyl)-L-homoserine lactone (3OC8HSL), which all belong to the AHL family. Analysis of AHL metabolic products by gas chromatography-mass spectrometry (GC-MS) led to the identification of -cyclohexyl-propanamide, and pentanoic acid, 4-methyl, methyl ester as the main intermediate metabolites, revealing that AHL could be degraded by hydrolysis and dehydroxylation. All intermediates were transitory and faded away without any non-cleavable metabolites at the end of the experiment. Furthermore, strain XN-10 significantly attenuated the pathogenicity of subsp. () to suppress tissue maceration in carrots, potatoes, and Chinese cabbage. Taken together, our results shed light on the QQ mechanism of a novel AHL-degrading bacterial isolate, and they provide useful information which show potential for biocontrol of infectious diseases caused by AHL-dependent bacterial pathogens.
群体感应（QS）是一种细胞密度依赖性机制，可调节微生物细胞中特定基因的表达。群体猝灭（QQ）是一种通过干扰病原体的QS系统来减弱致病性的有前景的策略。N-酰基高丝内酯（AHLs）在许多革兰氏阴性细菌病原体中充当信号分子，并受到广泛关注。在本研究中，从农业污染土壤中分离出一种新型高效的AHL降解细菌，菌株XN-10，并评估了其降解效率以及对QS介导的病原体的潜在用途。菌株XN-10能够有效降解N-（3-氧代己酰基）-L-高丝氨酸内酯（OHHL）、N-己酰基-L-高丝氨酸内酯（C6HSL）、N-（3-氧代十二酰基）-L-高丝氨酸内酯（3OC12HSL）和N-（3-氧代辛酰基）-L-高丝氨酸内酯（3OC8HSL），这些均属于AHL家族。通过气相色谱-质谱联用（GC-MS）对AHL代谢产物进行分析，鉴定出环己基丙酰胺和4-甲基戊酸甲酯为主要中间代谢产物，表明AHL可通过水解和脱羟基作用降解。所有中间产物都是暂时的，在实验结束时消失，没有任何不可裂解的代谢产物。此外，菌株XN-10显著减弱了胡萝卜软腐欧文氏菌胡萝卜亚种（Erwinia carotovora subsp. carotovora）对胡萝卜、土豆和大白菜的组织浸软致病性。综上所述，我们的结果揭示了一种新型AHL降解细菌分离株的QQ机制，并提供了有关对由AHL依赖性细菌病原体引起的传染病进行生物防治潜力的有用信息。
