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Physiology and Biochemistry

Characterization of Fatty Acid Methyl Ester Content of Clavibacter michiganensis subsp. michiganensis. R. D. Gitaitis, Associate professor, Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793-0748; R. W. Beaver, assistant research chemist, Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793-0748. Phytopathology 80:318-321. Accepted for publication 2 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-318.

Profiles of fatty acid methyl esters (FAMEs) obtained from strains of Clavibacter michiganensis subsp. michiganensis from Canada, the People?s Republic of China, Thailand, Taiwan, and the United States were analyzed by gas-liquid chromatography. The FAMEs of 45 such strains were highly similar and were characterized by the presence of saturated, branched-chain C12 to C17 fatty acids. Other FAMEs occurring in significant amounts were the saturated straight-chain fatty acids 12:0 and 16:0. The presence of unsaturated branched-chain a 15:1, anteisopentadecenoic acid, was highly specific for C. m. michiganensis. When the amount of a 15:1 exceeded 2.56% of the total profile, the confidence level for identification was P = 0.10. Other qualitative and quantitative differences in FAMEs also were used to distinguish C. m. michiganensis from morphologically similar gram-positive bacteria that grew on semiselective media. When plotted three dimensionally, FAMEs defined a spatial relationship among strains of C. m. michiganensis. The technique was used as an accurate and rapid method for the characterization of bacteria recovered from irrigation ponds, seed, soil, transplants, and weeds.