sp. AN090126 as a Biocontrol Agent against Bacterial and Fungal Plant Diseases.

Bacteria and fungi are major phytopathogens which substantially affect global agricultural productivity. In the present study, sp. AN090126, isolated from agricultural suppressive soil in Korea, showed broad-spectrum antagonistic activity against various phytopathogenic bacteria and fungi. In the 96-well plate assay, the fermentation filtrate of sp. AN090126 exhibited antimicrobial activity, with a minimum inhibitory concentration (MIC) of 0.63-10% for bacteria and 0.63-3.3% for fungi. The MIC of the partially purified fraction was 20.82-250 µg/mL for bacteria and 15.6-83.33 µg/mL for fungi. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that AN090126 produced various volatile organic compounds (VOCs), including dimethyl sulfide and trimethyl sulfide, which inhibited the growth of pathogenic bacteria and fungi in in vitro VOC assays. In pot experiments, the fermentation broth of sp. AN090126 reduced tomato bacterial wilt caused by , red pepper leaf spot caused by , and creeping bentgrass dollar spot caused by in a dose-dependent manner. Moreover, the secondary metabolites derived from this strain showed a synergistic effect with streptomycin sulfate against streptomycin-resistant subsp. , the causative agent of Kimchi cabbage soft rot, in both in vitro and in vivo experiments. Therefore, sp. AN090126 is a potential biocontrol agent in controlling plant diseases caused by pathogenic bacteria and fungi, specifically by the streptomycin-resistant strains.