Considering its disease-inducing nature and capacity, F. cf. incarnatum may have potentials to become an important causal agent of ginseng root rot. Bacillus species are usually found in diverse natural environments of soil, water, and air and have antifungal
effects against several kinds of plant fungal pathogens [21], [23] and [40]. They also show controlling capacities for root rots and Phytophthora blight of ginseng caused by Cylindrocarpon destructans and Phytophthora cactorum, respectively [22] and [33]. In our study, a bacterial isolate identified as Tenofovir molecular weight B. amyloliquefaciens B2-5 had a strong antagonistic activity against the causal pathogen of ginseng root rot, F. cf. incarnatum, showing strong inhibitory activity against mycelial growth and conidial germination that
play important roles in the infection cycle of the pathogen [17]. These attributes may make the bacterium useful for controlling the ginseng root rot caused by this fungal pathogen. The bacterial isolate B2-5 had the highest control efficiency of ginseng root rot caused by F. cf. incarnatum when it was applied 2 d prior to pathogen inoculation (by pretreatment); significantly lowered ABT-888 mouse control efficacies were observed in the simultaneous treatment and post-treatment. This suggests that the proper application time of the bacterial isolate may be any time prior to the disease occurrence as Bacillus spp. are durable in harsh environments due to endospore formation [41], which may be an advantage for easy formulation of the bacterial isolate for the commercialization of microbial fungicidal products. The mycelial growth of F. cf. incarnatum increased Glutathione peroxidase with temperature increase; however, the antagonistic activity of the bacterial isolate to the pathogen was enhanced much more than the fungal growth increase with a temperature increase up to
25°C, at which temperature the growth of the pathogen treated with antagonistic bacterium was reduced the most. This suggests that the antagonistic bacterium may exert its full disease-control capacity at a range of optimum temperatures in controlling the growths of the fungal pathogen and the half-heliophobus ginseng plant, and accordingly may lead to improved efficacy for the control of the root rot caused by F. cf. incarnatum. The inhibition of the conidial germination by the bacterial culture filtrate and the hyphal damages with no noticeable parasitism following the bacterial treatment as viewed by microscopy, suggest that bacterial antibiotics and other toxic compounds present in bacterial metabolites or a direct interaction might be responsible for the inhibition of the pathogen growth, for which antibiosis is the major action mode that exhibits instant disease control effects [42].