Anandan Kanmani, Vittal Ravishankar Rai
Department of Studies in Microbiology, University of Mysore, Manasagangotri, Mysore, 570006, India.
Department of Studies in Microbiology, University of Mysore, Manasagangotri, Mysore, 570006, India.
Microb Pathog. 2025 Mar;200:107356. doi: 10.1016/j.micpath.2025.107356. Epub 2025 Feb 5.
Phytopathogens are global threats to agriculture, causing substantial economic losses and decreased crop productivity. Developing a control strategy without emerging resistance or creating environmental and health hazards is necessary. The majority of potential pathogens of crops are gram-negative and they communicate through Acyl homoserine lactones (AHLs)-mediated quorum sensing (QS) systems to establish their pathogenicity. By synthesizing small signal molecules, they collectively respond, regulate the expression of virulence factors, biofilm development, secondary metabolite production, and interactions with the host and other microbes in a population-density-dependent manner. Targeting QS mechanisms has been put forward as an attractive approach for conventional infection control. The quorum quenching endophytic Bacillus thuringiensis strain KMCL07 cell free lysate (CFL) was used to attenuate the virulence of the soft-rot Pectobacterium carotovorum subsp. carotovorum (Pcc) by targeting its QS system. The CFL inhibition ability of Pcc on the AHL signal molecules were tested using a biosensor strain (Chromobacterium subtsugae), which showed a significant (p < 0.001) reduction in the production of AHL signalling molecules without inhibiting Pcc growth. Pcc pathogenicity is related to the expression of various virulence traits like the secretion of extracellular enzymes, motility, and biofilm. The test results showed a significant degree (p < 0.0001) of inhibition in the production of virulence-causing extracellular enzymes (Pel, Cel, and Prt) when Pcc was treated with CFL. Soft rot in-vitro assays revealed that CFL, irrespective of different families, showed a significant level (p ≤ 0.0001) of reduction in disease severity and effectively reduced tissue maceration under different temperature ranges (25°, 30°, and 40 °C). LC-MS analysis confirmed the hydrolytic degradation of QS signalling molecules (3-oxo-C6-HSL and 3-oxo-C8-HSL) by CFL indicating the presence of lactonase enzyme activity. These results suggest that CFL can degrade a wide range of AHL molecules, and control soft rot in a wide variety of hosts and temperatures without affecting the host. Applying cell free lysates (CFLs) from endophytic bacteria to control soft rot pathogens can be an environmentally friendly way to improve plant health. CFLs protect plants by preventing the establishment of pathogenic organisms.
植物病原体是农业面临的全球性威胁，会造成巨大的经济损失并降低作物产量。制定一种不会产生新抗性、也不会造成环境和健康危害的控制策略很有必要。大多数潜在的作物病原体是革兰氏阴性菌，它们通过酰基高丝氨酸内酯（AHLs）介导的群体感应（QS）系统进行通讯，以确立其致病性。通过合成小信号分子，它们共同做出反应，以群体密度依赖的方式调节毒力因子的表达、生物膜形成、次生代谢产物的产生以及与宿主和其他微生物的相互作用。针对QS机制已被提出作为传统感染控制的一种有吸引力的方法。群体淬灭内生苏云金芽孢杆菌KMCL07菌株的无细胞裂解物（CFL）被用于通过靶向软腐胡萝卜软腐果胶杆菌胡萝卜软腐亚种（Pcc）的QS系统来减弱其毒力。使用生物传感器菌株（杉叶杆菌）测试了CFL对Pcc的AHL信号分子的抑制能力，结果显示AHL信号分子的产生显著减少（p < 0.001），且未抑制Pcc的生长。Pcc的致病性与各种毒力特性的表达有关，如细胞外酶的分泌、运动性和生物膜。测试结果表明，当用CFL处理Pcc时，致病细胞外酶（Pel、Cel和Prt）的产生受到显著抑制（p < 0.0001）。软腐体外试验表明，无论属于不同家族，CFL均能显著降低病害严重程度（p≤0.0001），并在不同温度范围（25°、30°和40°C）有效减少组织浸软。液相色谱 - 质谱分析证实CFL对QS信号分子（3 - 氧代 - C6 - HSL和3 - 氧代 - C8 - HSL）有水解降解作用，表明存在内酯酶活性。这些结果表明，CFL可以降解多种AHL分子，并在不影响宿主的情况下，在多种宿主和温度下控制软腐病。应用内生细菌的无细胞裂解物（CFLs）来控制软腐病原体可能是一种改善植物健康的环保方法。CFLs通过阻止致病生物的定殖来保护植物。
