Identification of a strain Paenibacillus elgii SWL-W8 and its biocontrol effect against soft rot of Chinese cabbage

The bacterial strain SWL-W8 with good antagonism against the soft rot pathogen Pectobacterium carotovorum subsp. carotovorum was isolated from the hot springs at Tengchong City in Yunnan Province. The purpose of this study was to identify the strain, evaluate its antibacterial ability, and study the control effect of the strain against soft rot of Chinese cabbage. Based on its morphological characterisitcs, the BIOLOG identification results, and the annalysis of its 16S rDNA sequence, strain SWL-W8 was identified to be a member of Paenibacillus elgii. It exhibited inhibitory activities against several pathogens, including the pathogenic P. carotovorum that causes bacterial soft rot in plants. Whole genome sequencing analysis of strain SWL-W8 using nanopore sequencing technique indicated that the strain harbors encoding genes of lipopeptides, peptidoglycans, and polyketide resistant compounds such as surfactin, polyketide, subtilisin, chitinase, bacillibactin, fusaricidin and elgicin. SWL-W8 could easily colonize in soil. In pot experiments, the protection and cure efficacy of SWL-W8 bacterial suspension at a concentration of 1.0 × 10⁶ cfu/mL against soft rot of Chinese cabbage were 79.7% and 64.4%, respectively. In addition, SWL-W8 bacterial suspension promoted the seeds germination and Chinese cabbage growth. In conclusion, strain SWL-W8 is a potential candidate for further development in plant disease control.