Submitted to: Crop Protection Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2001
Publication Date: 1/1/2002
Citation: Li, W., Roberts, D.P., Dery, P.D., Meyer, S.L., Lohrke, S.M., Lumsden, R.D., Hebbar, K.P. 2002. Broad spectrum anti-biotic activity and disease suppression by the potential biocontrol agen burkholderia ambifaria BC-F. Crop Protection. 21:129-135. Interpretive Summary: Soilborne plant pathogenic fungi and nematodes cause diseases that result in major economic losses to farmers in the United States. Biological control measures for these diseases need to be developed due to environmental problems associated with existing chemical controls. The potential biocontrol bacterium Burkholderia ambifaria BC-F was partially characterized. It was shown that B. ambifaria BC-F was able to colonize the roots of several important crops in different soils. It was also shown that B. ambifaria BC-F produces a broad spectrum anti-biotic compound that is capable of inhibiting several important soilborne plant pathogenic fungi and the root-knot nematode. This information will be useful to scientist developing B. ambifaria as a biological control agent.
Technical Abstract: Burkholderia ambifaria isolate BC-F when applied as a seed coating significantly suppressed damping-off of cucumber and soybean caused by Pythium ultimum. Cucumber and soybean seed coated with a pead bond formulation of isolate BC-F had significantly greater plant strands than the non-treated pathogen controls in potting mix. Soybean seeds treated isolate BC-F had significantly greater plant fresh weight per pot and plan height per pot than the pathogen control. Isolate BC-F effectively colonized the roots of corn, cucumber, soybean, and sunflower and was detected at >105 colony-forming-units per gram fresh weight of root after four weeks in two different natural soils. B. ambifaria BC-F grown on nutrient broth agar or potato dextrose agar released a diffusable metabolite(s) that inhibited hyphal growth of P. ultimum, R. solani, P. capsici, and Fusarium oxysporum f. sp. lycopersici. Culture filtrates from misolate BC-F grown on nutrient broth contained a metabolite(s) that inhibited egg hatch and mobility of second-stage juveniles of M. incognita. These culture filtrates contained chitinase, lamarinase, and protease activities. However, the <3 kDa fraction of these culture filtrates was responsible for the inhibition of M. incognita. The >8 kDa fraction contained no inhibitory activity, indicating that inhibition of egg hatch and mobility of second-stage juveniles was not directly due to chitinase, laminarinase, and protease activities. The demonstrated ability of isolate BC-F to suppress disease caused by animal and fungal pathogens of many crop plants may be due to 1) the ability of isolate BC-F to persist for long periods in association with roots of diverse crop plants in different soils and 2)production of metabolite with broad spectrum anti-biotic activity.