Studies on the Relationship between Virulence and Bacteriological Properties in Erwinia carotovora subsp. Carotovora

Nineteen wild-type strains of Erwinia carotovora subsp. carotovora isolated in Japan were classified into 3 groups on the basis of their virulence to slices of potato tuber. On the other hand, these strains were divided into 6 biovars on the basis of the differences in both methyl red reaction and acid production from maltose and sorbitol. No relationship was found between virulence and biovars. The activities of pectolytic, cellulolytic and proteolytic enzymes excreted from these strains were also examined by means of agar plate method. Indistinct correlation between virulence and enzyme activities in wild-type strains was observed. The mutant strains attenuated in virulence which were originated from the virulent strains by N-methyl-N’-nitro-N-nitrosoguanidine (NTG) treatment, also attenuated in enzyme activities, though several exceptions were observed. Among virulent mutant strains, those negative in enzyme activity were also found.