Efficacy of plant growth-promoting bacteria Streptomyces werraensis F3 for chemical modifications of diseased soil of ginseng

Rust rot and root rot of ginseng are common soil-borne diseases with an annual incidence of 20–50%. Here, a strain of Streptomyces werraensis, F3, isolated from ginseng rhizosphere was evaluated for its antifungal activity against ginseng root rot and rust rot-causing pathogens and for its growth-promoting properties. To further assess the potential agricultural use of F3, a pot experiment was performed using ginseng. The results showed that the inhibition rates of F3 bacterial suspension against the mycelial growth of rust rot and root rot pathogens in ginseng were 66.7% and 65.5%, respectively. Compared with the negative control, the germination concise vigour index of ginseng seed increased by 7.25 units upon treatment of the ginseng soil with F3, which could secrete indoleacetic acid and effectively promote the germination of ginseng. The pot experiment proved that F3, when applied as a biological control bacterial agent, improved the pH, organic matter, rapidly available nitrogen, available phosphorus, and available potassium, and the microbial community structure of the soil exposed to the disease for varying time periods. S. werraensis F3 has great potential to be commercialised as a biological control agents and a plant growth-promoting agent to effectively manage ginseng rust rot and root rot diseases.