|Kang, Sun Chul|
Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2009
Publication Date: 5/1/2009
Citation: Bajpai, V.K., Kim, H., Hou, C.T., Kang, S. 2009. Microbial conversion and in vitro and in vivo antifungal assessment of bioconverted docosahexaenoic acid (bDHA) against agricultural plant pathogenic fungi. Journal of Industrial Microbiology and Biotechnology. 36(5):695-704. Interpretive Summary: Previously, we discovered a new microbial culture Pseudomonas aeruginosa PR3 that produced 7,10-dihydroxy-fatty acid from oleic acid. Hydroxy fatty acids are useful as starting materials for the synthesis of specialty chemicals, special military nylon, plastisizers, coating materials and possible as physiologically active agents. Now we found that strain PR3 coverts docosahexaenoic acid (DHA) to oxygenated products (bDHA). bDHA shows potential for controlling plant pathogenic fungi such as Botrytis cinerea, Colletotrichum capsici, Fusarium oxysporum, Fusarium solani, Phytophthora capsici, Rhizoctonia solani and Sclerotinia sclerotiorum. These findings raise the possibility of using microbial bioconverted fatty acid products as antifungal agents to control severe plant fungal diseases.
Technical Abstract: The goal of this research is to develop potential antifungal agents through the microbial conversion of docosahexaenoic acid. Bioconverted docosahexaenoic acid (bDHA), obtained from the microbial conversion of docosahexaenoic acid by Pseudomonas aeruginosa PR3, was assessed for its in vitro and in vivo antifungal potential. Mycelial growth inhibition of test plant pathogens such as Botrytis cinerea, Colletotrichum capsici, Fusarium oxysporum, Fusarium solani, Phytophthora capsici, Rhizoctonia solani and Sclerotinia sclerotiorum was measured in vitro. bDHA (5 ul/disc), corresponding to 5000 ug/ml inhibited 55.30 to 65.90% fungal mycelium radial growth of all the tested plant pathogens. Minimum inhibitory concentrations (MICs) of bDHA against the tested plant pathogens were found in the range of 125 to 500 ug/ml. Also, bDHA had a strong detrimental effect on spore germination for all the tested plant pathogens. Further, three plant pathogenic fungi namely C. capsici, F. oxysporum and P. capsici were subjected to an in vivo antifungal screening. bDHA at the varied concentrations revealed promising antifungal effect in vivo. The results of this study indicate that bDHA has potential value to control plant pathogenic fungi. The microbial bioconversion of unsaturated fatty acids may prove to be very valuable in generating potential antifungal agents to control severe plant fungal diseases.