Laboratory of Enzymatic Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173-3038, Sfax, Tunisia.
Laboratory of Genetic Resources of Olive Tree : Characterization, Valorization and Phytosanitary Protection, Olive Tree Institute, University of Sfax, 3038, Sfax, Tunisia.
Curr Microbiol. 2024 Apr 16;81(6):142. doi: 10.1007/s00284-024-03660-6.
The present work aims to quantitatively and qualitatively monitor the production of lipopeptide mixtures by Bacillus methylotrophicus DCS1 strain in Landy medium and to investigate the antifungal activities of DCS1 strain and its produced lipopeptides. The in vitro activities were tested by the direct confrontation and agar well diffusion methods, while the in vivo study was carried out in order to test the efficiency of DCS1 bacterial suspension in the control of Fusarium wilt in tomato plants. Identification of lipopeptides by mass spectrometry (LC/MSD-TOF) showed that lipopeptide isoforms produced during the first 24 h and 48 h of fermentation are identical, belonging to bacillomycin D and fengycins A and B homologues with a difference in the yield of production. After 72 h of fermentation corresponding to the end of incubation period, B. methylotrophicus DCS1 is able to produce a mixture of surfactin, pumilacidin, iturin A/mycosubtilin, iturin C1, bacillomycin D and fengycins A and B isoforms. The results of in vitro antifungal experiments suggest that B. methylotrophicus DCS1 has a significant potential as a biocontrol agent, owing to lipopeptides produced, endowed with antifungal activity against several phytopathogenic fungi. The curative treatment of tomato plants with DCS1 bacterial suspension was more effective in the protection against Fusarium oxysporum f. sp. radicis-lycopersici (FORL) than the preventive treatment by comparing the average number of leaves remaining healthy after 30 days of each treatment and the appearance of tomato plants roots. The results indicate that B. methylotrophicus DCS1 exhibit a significant suppression of Fusarium wilt symptoms in tomato plants comparable to that of commercial fungicides and could be an alternative to chemically synthesized pesticides.
本工作旨在定量和定性监测甲基营养型芽孢杆菌 DCS1 菌株在 Landy 培养基中的脂肽混合物的生产，并研究 DCS1 菌株及其产生的脂肽的抗真菌活性。体外活性通过直接对抗和琼脂孔扩散方法进行测试，而体内研究则进行了测试，以测试 DCS1 细菌悬浮液在控制番茄植物枯萎病中的效率。通过质谱（LC/MSD-TOF）鉴定脂肽表明，发酵前 24 小时和 48 小时产生的脂肽异构体相同，属于芽孢杆菌素 D 和丰原素 A 和 B 同系物，产量有所不同。发酵 72 小时后，即培养期结束时，B. methylotrophicus DCS1 能够产生表面活性剂、 pumilacidin、iturin A/mycosubtilin、iturin C1、芽孢杆菌素 D 和丰原素 A 和 B 异构体的混合物。体外抗真菌实验结果表明，由于产生的脂肽具有抗几种植物病原真菌的活性，B. methylotrophicus DCS1 具有作为生物防治剂的巨大潜力。与预防性处理相比，用 DCS1 细菌悬浮液对番茄植物进行治疗性处理在保护番茄植物免受尖孢镰刀菌根腐病（FORL）方面更为有效，通过比较每种处理后 30 天保持健康的叶片数量平均值和番茄植物根系的外观。结果表明，B. methylotrophicus DCS1 对番茄植物枯萎病症状的抑制作用与商业杀真菌剂相当，可能是化学合成农药的替代品。
