ERWINIA APHIDICOLA, A NEW SPECIES ISOLATED FROM PEA APHID, ACYRTHOSIPHON-PISUM

Five strains of Gram-negative, oxidase-negative, facultatively anaerob ic, fermentative, motile, rod-shaped bacterium with the general charac teristics of the family Enterobacteriaceae were isolated from the gut of multiple specimens of the pea aphid. All the strains caused aphid m ortality when ingested by insects via a synthetic diet, The results of biochemical tests showed that these strains are most related to Erwin ia herbicola and Pantoea agglomerans. According to DNA-DNA hybridizati on, the five strains showed more than 96% relatedness to each other, i ndicating that these organisms are members of a single species, These strains were most closely related to Erwinia herbicola (22% DNA relate dness). Phenotypic differentiation of these strains from Erwinia herbi cola, which was also detected from aphid gut, was based on negative re actions in tests of yellow pigment production, gelatin liquefaction, a cid production from inulin, starch and dulcitol, and positive acid pro duction from melibiose, inositol, cellobiose and glycerol. On the basi s of these data, the name Erwinia aphidicola is proposed for the new o rganism. The type strain is strain X 001 (=IAM 14479).