Submitted to: Plant Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2015
Publication Date: 3/12/2015
Publication URL: http://handle.nal.usda.gov/10113/60630
Citation: Dunlap, C.A., Schisler, D.A., Bowman, M.J., Rooney, A.P. 2015. Genomic analysis of Bacillus subtilis OH 131.1 and coculturing with Cryptococcus flavescens for control of fusarium head blight. Plant Gene. 2:1-9.
Interpretive Summary: ARS Researchers in Peoria, IL, completed the genome of a bacterium which had previously been shown to be effective in managing Fusarium Head Blight in wheat. The completed genome allowed the researcher to predict what bioactive metabolites the strain is capable of producing. Additionally, they evaluated combining the bacteria with a yeast antagonist for enhance biocontrol activity. The study demonstrated combining the strains increased their efficacy. This work provides insight into the modes of action the strain may utilize in its biological activity and to identify related strains that may also benefit wheat producers and consumer by reducing the impact of Fusarium Head Blight disease.
Technical Abstract: Bacillus subtilis OH131.1 is a bacterial antagonist of Fusarium graminearum, a plant pathogen which causes Fusarium head blight in wheat. The genome of B. subtilis OH131.1 was sequenced, annotated and analyzed to understand its potential to produce bioactive metabolites. The analysis identified 6 synthetic clusters for metabolites that could impact biocontrol efficacy. Five of the clusters were confirmed functional with HPLC-MS/MS of the culture supernatant. The analysis also provided the data to determine the phylogeny of the subject strain. The phylogeny results characterize the strain as Bacillus subtilis subsp subtilis. Comparative genomics was used to compare the genome of B. subtilis OH131.1 with closely related strains. Previously, the culture supernatant of B. subtilis OH131.1 showed no antifungal activity, which suggested it may be a suitable candidate to combine with a yeast antagonist (Cryptococcus flavescens OH182.9) of Fusarium head blight for possible enhanced biocontrol efficacy. Cocultures of B. subtilis OH131.1 and C. flavescens OH 182.9 were produced with varying ratios of the starting inoculum of the two strains. The strains alone and the various ratios were evaluated for biocontrol activity in greenhouse assays. Co-cultures of B. subtilis OH 131.1 and C. flavescens OH 182.9 initially inoculated at a ratio of 1:100 or 1:10, respectively, were the most effective in reducing disease symptoms compared to the control. This study reports the first coculturing of bacterial and yeast biocontrol antagonists and their efficacy in greenhouse assays.