Bacillus subtilis Z15 (BS-Z15), isolated from cotton rhizosphere soil, inhibits Verticillium dahliae and suppresses cotton Verticillium wilt in pot experiments. We investigated the influence of environmental factors, pH, temperature, ultraviolet light, protease, and incubation time on the stability of BS-Z15 secondary metabolites (SMs), and the mechanism underlying the cytotoxicity of BS-Z15 SMs on V. dahliae. BS-Z15 and its fermentation broth inhibited V. dahliae, and this effect was mediated by its SMs. These were shown to be stable to the influence of the above environmental factors. BS-Z15 SMs decreased the viability of V. dahliae conidia in a time-dependent manner. Scanning electron microscopy showed that BS-Z15 and its SMs resulted in flattened and depressed conidia. BS-Z15 SMs induced morphological abnormalities in the hyphae, which showed rough aberrant structures, reduced conidiophore production, and accelerated aging. Flow cytometry using Hoechst/propidium iodide double staining revealed that BS-Z15 SMs induced necrosis in V. dahliae in a time-dependent manner. Fluorescence microscopy showed that BS-Z15 SMs did not induce apoptotic bodies in the conidia of V. dahliae but caused significant changes in karyotypes, accompanied by nuclear lysis and nucleic-acid diffusion, which may play important roles in necrosis. In addition, 0.3 mg/mL BS-Z15 SMs had no effect on either the mitochondrial membrane potential or the synthesis of proapoptotic proteins, indicating that the SMs did not induce apoptosis in V. dahliae. Their lethal effect on V. dahliae was by inducing necrosis in its conidia and hyphae. BS-Z15 SMs thus have potential as biological pesticides to control Verticillium wilt in cotton.

在盆栽试验中，枯草芽孢杆菌Z15（BS-Z15）从棉花根际土壤中分离出来，可抑制大黄萎病菌并抑制棉花黄萎病。我们调查了环境因素，pH值，温度，紫外线，蛋白酶和孵育时间对BS-Z15次生代谢产物（SMs）稳定性的影响，以及BS-Z15 SM对大丽花蛾细胞毒性的潜在机制。BS-Z15及其发酵液可抑制大丽花弧菌，其作用是由其SM介导的。这些被证明对上述环境因素的影响是稳定的。BS-Z15的SM下降的生存能力黄萎病分生孢子具有时间依赖性。扫描电子显微镜显示，BS-Z15及其SM导致分生孢子扁平和凹陷。BS-Z15 SMs引起菌丝形态异常，表现出粗糙的异常结构，降低了分生孢子的产生，并加速了衰老。使用Hoechst /碘化丙啶双重染色的流式细胞仪显示，BS-Z15 SMs以时间依赖性方式诱导大丽花弧菌坏死。荧光显微镜显示，BS-Z15 SMs不会在大疱弧菌的分生孢子中诱导凋亡小体。但会导致核型显着变化，并伴随核溶解和核酸扩散，这可能在坏死中起重要作用。此外，0.3 mg / mL BS-Z15 SM对线粒体膜电位或促凋亡蛋白的合成均无影响，表明该SM不会诱导大丽花弧菌的凋亡。它们对大丽菌的致死作用是在其分生孢子和菌丝中引起坏死。因此，BS-Z15 SM具有作为生物农药的潜力，可以控制棉花中的黄萎病。