The Erwinia-Coliform Relationship

Abstract

19 isolates of the genus Erwinia (soft-rot group) could be classified on the basis of lactose fermentation as aberrant eoliforms. On the basis of their IMViC pat-terns, the majority would seem to approximate Escherichia freundii. But, according to their gelatin-liquefying ability, motility and production of acid in glycerol, the relationship seems to be closer to Aerobacter cloacae. 16 of the cultures possessed the ability to macerate vegetable tissue. This characteristic was not shared by any of 50 coliform cultures. All but 2 of the Erwinia isolates fermented pectin in a synthetic medium, while 22 of the 50 coliform organisms including 3 Escherichia of fecal origin, did so. There was no correlation between the ability to disorganize plant tissue and pectin fermentation. On the basis of this macerating ability, it is contended that the placing of soft-rot organisms in a genus (Erwinia) separate from the coliforms is valid. At the same time the close relationship of the 2 groups is recognized.