Bacillus subtilis is ubiquitous and capable of producing various metabolites, which make the bacterium a good candidate as a biocontrol agent for managing plant diseases. In this study, a phyllosphere bacterium B. subtilis PMB102 isolated from tomato leaf was found to inhibit the growth of Alternaria brassicicola ABA-31 on PDA and suppress Alternaria leaf spot on Chinese cabbage (Brassica rapa). The genome of PMB102 (Accession no. CP047645) was completely sequenced by Nanopore and Illumina technology to generate a circular chromosome of 4,103,088 bp encoding several gene clusters for synthesizing bioactive compounds. PMB102 and the other B. subtilis strains from different sources were compared in pangenome analysis to identify a suite of conserved genes involved in biocontrol and habitat adaptation. Two predicted gene products, surfactin and fengycin, were extracted from PMB102 culture filtrates and verified by LC–MS/MS. The antifungal activity of fengycin was tested on A. brassicicola ABA-31 in bioautography to inhibit hyphae growth, and in co-culturing assays to elicit the formation of swollen hyphae. Our data revealed that B. subtilis PMB102 suppresses Alternaria leaf spot by the production of antifungal metabolites, and fengycin plays an important role to inhibit the vegetative growth of A. brassicicola ABA-31.

枯草芽孢杆菌无处不在，能够产生各种代谢物，这使得该细菌成为控制植物病害的生物防治剂的良好候选者。在这项研究中，发现从番茄叶中分离出的一种叶际细菌B. subtilis PMB102 能够抑制PDA上Alternaria brasicicola ABA-31的生长，并抑制大白菜（Brassica rapa）上的 Alternaria 叶斑病。PMB102（登录号CP047645）的基因组通过Nanopore和Illumina技术完全测序，产生4,103,088 bp的环状染色体，编码几个用于合成生物活性化合物的基因簇。PMB102 和其他B. subtilis在泛基因组分析中比较了来自不同来源的菌株，以确定一组涉及生物控制和栖息地适应的保守基因。从 PMB102 培养物滤液中提取了两种预测的基因产物，surfactin 和 fengycin，并通过 LC-MS/MS 进行验证。在生物自显影中对A. brasicicola ABA-31的抗真菌活性进行了测试，以抑制菌丝生长，并在共培养试验中检测到形成肿胀的菌丝。我们的数据显示，枯草芽孢杆菌PMB102 通过产生抗真菌代谢物来抑制链格孢菌叶斑病，并且芬霉素在抑制A. brasicicola ABA-31的营养生长方面起着重要作用。