BREEDING SELECTION AND MOLECULAR CHARACTERIZATION FOR IMPROVED SUGAR BEET GERMPLASM
Location: Sugarbeet and Bean Research
Title: Characterizing a novel strain of Bacillus amyloliquefaciens BAC03 for potential biological control application
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 30, 2012
Publication Date: October 18, 2012
Citation: Meng, Q.X., Jiang, H.H., Hanson, L.E., Hao, J.J. 2012. Characterizing a novel strain of Bacillus amyloliquefaciens BAC03 for potential biological control application. Journal of Applied Microbiology. 113:1165-1175.
Interpretive Summary: A strain of Bacillus, BAC03, that had been isolated from soil suppressive to common scab development in potato was characterized. BAC03 was identified as Bacillus amyloliquefaciens using molecular methods. The isolate inhibited the growth of several bacteria, fungi, and oomycetes in plate tests using co-culturing of the organisms. When tested in the greenhouse, BAC03 applied to potting mix decreased the severity of common scab for both potato and radish, but showed no effect when applied as a foliar spray. Seedling emergence of radish was reduced when BAC03 was applied to the potting mix at planting, but there was no effect on potato emergence. No growth inhibition was observed when BAC03 was applied to soil after plant emergence, but care should be used if this organism is used with seeds or seedlings. An antimicrobial substance was extracted from BAC03 that was identified as an LCI protein. This material was stable under a range of temperatures and pH levels. This organism shows potential for use as a biological control agent, particularly against common scab of potato, and possibly other root crops affected by common scab.
Aims: Identify and characterize a bacterial strain from suppressive soil, BAC03, evaluate its antimicrobial activity against Streptomyces scabies and other microorganisms, and characterize an antimicrobial substance produced by this strain.
Methods and Results: Bacterial strain BAC03 (isolated from common scab-suppressive soil) was identified as Bacillus amyloliquefaciens by analyzing sequences of fragments of the recA, recN, cheA, and gyrA genes. On various media, BAC03 displayed a broad spectrum of antagonistic activity against bacteria, fungi, and oomycetes using a co-culture method. In greenhouse assays, BAC03 applied in potting mix significantly reduced common scab severity (P < 0.05), and reduced S. scabies population as measured by quantitative real-time polymerase chain reaction. Potato showed potential yield increases following treatment. Foliar spray with BAC03 did not significantly affect disease severity or plant growth. BAC03 applied in potting mix inhibited the emergence of radish seedlings, but not affected potato emergence from seed tubers. An antimicrobial substance extracted from BAC03 by ammonium sulfate precipitation was identified as an LCI protein using liquid chromatography-mass spectrometry. The liquid culture of BAC03 and extracted substance were stable under a wide range of temperatures, pH levels, and following exposure to several chemicals.
Conclusions: Bacillus amyloliquefaciens strain BAC03 displayed strong antimicrobial activities, suppression of potato common scab, and potential enhancement of plant biomass.
Significance and Impact of the Study: Strain BAC03 has the potential to be developed to a commercial biocontrol agent.