Lysobacter enzymogenes LE16 autolysates have potential as biocontrol agents— Lysobacter sp. autolysates as biofungicide

Aims Biological techniques can manage plant diseases safely and in environmentally friendly ways, but their efficacy needs improvement. It is of the utmost importance to search for powerful microbes for the effective control of plant diseases. Methods and Results Unheated self-digestive solutions (SDS) that were heated at 100°C for 30 min(H-SDS) or stored for 12 months at room temperature (S-SDS) were prepared from Lysobacter enzymogenes LE16 broth culture to study their potential as biocontrol agents. This bacterium produced protease, phosphatase, lysozyme and siderophores in pure culture as well as 12 secondary metabolites including novel antibiotics lysobactin, WAP-8294A2 and mupirocin determined based on the antiSMASH 5.0.0 blast database. A poison plate assay revealed the antagonistic activities of SDS, H-SDS and S-SDS against an animal pathogenic bacterium Staphylococcus aureus, a phytopathogenic bacterium Pseudomonas syringae pv. tabaci, and numerous plant pathogenic fungi and oomycetes, including Colletotrichum gloeosporioides, Penicillium italicum, Alternaria alternate, Rhizoctonia solani, Didymella bryoniae, Sclerotinia sclerotiorum, Phytophthora nicotianae and Phytophthora capsici. The greenhouse experiment showed that SDS was highly effective in controlling pepper blight disease, which is caused by P. capsici. Compared with only pathogen inoculation, the application of SDS to the soil in preventive or curative treatments significantly reduced the disease incidence and index with relatively high control efficacy of 86·2–93·1%. Conclusions SDS enriched lytic enzymes, siderophores and antibiotics, has a wide antimicrobial spectrum, and shows potential as a new, safe and effective biocontrol agent against plant diseases. Significance and Impact of the Study Autolysates of the new biocontrol bacterium L. enzymogenes LE16 demonstrated the potential for industrial production and commercial use as a promising biocontrol agent in agriculture.