Isolation, identification, and control effect of a biocontrol bacterium for lotus root rot disease

Abstract Lotus rot is harmful to the underground stems and roots of plants. The center of the vascular bundle is brown or light brown at the beginning of the disease. After the pathogen spreads, it causes the leaves to roll over. The edges of leaves appear to have water invasion necrosis until the entire leaf tissue rots and dies. An endophytic bacterium that showed an apparent inhibitory effect on a specific type of Fusarium oxysporum, the pathogen of lotus root rot disease, was isolated from lotus root tissue. The bacterium, named LS8 (also known as strain CGMCC 24563 according to the General Microbiology Center of China Microbial Species Conservation and Management Committee), was identified as Bacillus velesiensis using physiological and biochemical identification methods and 16S rDNA sequencing. Soaking lotus seeds in LS8 culture medium with a concentration of 108 CFU for 12 h could significantly reduce the incidence of the disease in leaves and exert a control effect of up to 60.42% on the germination of lotus leaves rot. B. velesiensis LS8 has a significant biocontrol effect on lotus rot and could potentially be used to develop biocontrol agents.