ERWINIA-CAROTOVORA SUBSP ODORIFERA SUBSP NOV, ASSOCIATED WITH ODOROUS SOFT ROT OF CHICORY (CHICHORIUM-INTYBUS L)

Eleven strains of Erwinia carotovora that were isolated mainly, but not exclusively, from slimy rot of witloof chicory and were previously designated "atypical" E. carotovora subsp. atroseptica strains were characterized and compared with strains of E. carotovora subsp. carotovora, E. carotovora subsp. atroseptica, and Erwinia chrysanthemi (including the type strains). The 11 atypical E. carotovora subsp. atroseptica strains produced a typical bananalike odor when they were inoculated onto witloof chicory leaves. DNA-DNA homology experiments, biochemical tests, tests to determine carbon utilization patterns, and tests to identify the volatile metabolites produced from rotting witloofs were performed. The volatile end products of witloof decay were analyzed by ps chromatography. Alcohols, methylketones, and ethylacetate were produced by all of the Erwinia strains which we studied, whereas propyl acetate, isobutyl acetate, isoamyl acetate, and 2-actamyl acetate were produced only by the flavoring witloof soft-rot strains. A DNA relatedness study was performed by hybridizing DNAs with a tritium-labeled DNA and estimating the DELTAT(m) values (DELTAT(m) is the difference between the thermal denaturation midpoint of a homoduplex and the thermal denaturation midpoint of a heteroduplex). The 11 flavoring strains constituted a tight DNA hybridization group (79 to 91% related to type strain CFBP 1878 isolated from witloof). Strains of E. carotovora subsp. carotovora were 59 to 88% related to strain CFBP 1878T (T = type strain) (DELTAT(m) range, 3 to 4.5-degrees-C), indicating that they belonged to the same species but another subspecies. E. carotovora subsp. atroseptica and E. carotovora subsp. betavasculorum appeared to be less closely related to strain CFBP 1878T than E. carotovora subsp. carotovora was, exhibiting 53% homology (DELTAT(m), 7-degrees-C) and 48 to 51% homology (DELTAT(m), 8.5-degrees-C), respectively, with strain CFBP 1878T. Therefore, we propose that the 11 flavoring strains are members of a new subspecies, Erwinia carotovora subsp. odorifera. We examined 95 biochemical characteristics, API strip tests, and assimilation tests in Biotype galleries and identified nine tests which can be used for phenotypic differentiation of the new subspecies.