1986 Volume 52 Issue 1 Pages 69-77
Various kinds of soft rot bacteria were isolated from rhizomes of wasabi or Japanese horse radish (Eutrema wasabi Maxim.) with the internal black rot syndrome as well as from fibrous roots showing black stele symptoms. These bacteria included Erwinia spp. and Pseudomonas spp. Based on the bacteriological characteristics, Erwinia soft rot bacteria were divided into 4 groups. The strains of group 1 were identified as E. rhapontici which failed to produce pink diffusible pigment on any kinds of media used in the study. The strains of group 4 were identified as E. carotovora subsp. carotovora. The strains of group 3 were also identical with subsp. carotovora although they differed from the former in a few phenotypic characters. The strains of group 2 differed from subsp. carotovora in properties such as delayed acid production from lactose, absence of β-galactosidase, inability to utilize melibiose and raffinose, absence of growth in KCN broth, in 5% NaCl broth and at 36 C. This group should be classified as a new taxon in the genus Erwinia. Pseudomonas soft rot bacteria were divided into 5 groups by the bacteriological tests. The strains of groups 1, 2, and 5 were identified as P. marginalis (=biovar II of P. fluorescens) based on their overall similarity of phenotypic characteristics. The strains of group 4 were identified as P. viridiflava although they differed from the description of the bacterium in the literature in some minor characters. The strains of group 3 were also identical to P. viridiflava in the characteristics of the LOPAT test. However, the physiological and biochemical properties were significantly different from those of any of the soft rot pseudomonads hitherto described. Therefore, the taxonomic attributes of this group remain to be determined by more detailed comparative studies in future.