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Brown patch caused by the basidiomycete fungus Rhizoctonia solani is an economically important disease of cool-season turfgrasses. In order to manage the disease, different types of fungicides have been applied, but the negative impact of fungicides on the environment continues to rise. In this study, the beneficial bacteria Bacillus velezensis GH1-13 was characterized as a potential biocontrol agent to manage brown patch disease. The strain GH1-13 strongly inhibited the mycelial growth of turf pathogens including different anastomosis groups of R. solani causing brown patch and large patch. R. solani AG2-2(IIIB) hyphae were morphologically changed, and fungal cell death resulted from exposure to the strain GH1-13. In addition, the compatibility of fungicides with the bacterial strain, and the combined application of fungicide azoxystrobin and the strain in brown patch control on creeping bentgrass indicated that the strain could serve as a biocontrol agent. To develop strain-specific detection method, two unique genes from chromosome and plasmid of GH1-13 were found using pan-genome analysis of 364 Bacillus strains. The unique gene from chromosome was successfully detected using both SYBR Green and TaqMan qPCR methods in bacterial DNA or soil DNA samples. This study suggests that application of GH1-13 offers an environmentally friendly approach via reducing fungicide application rates. Furthermore, the developed pipeline of strain-specific detection method could be a useful tool for detecting and studying the dynamics of specific biocontrol agents.

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Agricultural and livestock microorganisms including bacteria, yeast and fungi have been used as eco-friendly biological agent in plant growth promoting, disease suppression and odor reduction. In this study, we have optimized culture conditions of three species, such as Bacillus subtilis, Saccharomyces cerevisiae and Lactobacillus casei that could act as effective biological agent by producing growth-promoting factors to crops. They also reduce harmful odors generated from livestock manure. We made up the optimal media recipes for Bacillus subtilis, Saccharomyces cerevisae and Lactobacillus casei named as MMS (glucose 0.5%, soy bean flour 0.8%, NaCl 0.15%, K 2 HPO 4 0.25%, Na 2 CO 3 0.05%, MgSO 4 0.1%), YSM (dextrose 1%, soytone 0.5%, yeast extract 0.5%) and LSM (glucose 2%, soytone 0.5%, casein milk 0.5%, NaAc 0.5%, KH 2 PO 4 0.2%, MgSO 4 0.002%, MnSO 4 0.05%), respectively. The culture period of three microorganisms were determined on 30 hours in 500 L fermenter. In addition, the maximal cell growth of Bacillus subtilis, Saccharomyces cerevisae and Lactobacillus casei was measured as 1.4×10 9 cfu/mL, 6.4×10 8 cfu/mL, 3.3×10 9 cfu/mL, respectively. From above results, we represent that development of practical media and cultural techniques can economize heavily the cost for mass production of agricultural and livestock microorganisms.

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