Pectobacterium jejuense sp. nov. Isolated from Cucumber Stem Tissue

초록

A single Pectobacterium-like strain named 13-115(T) was isolated from a specimen of diseased cucumber stem tissue collected on Jeju Island, South Korea. The strain presented a rod-like shape and was negative for Gram staining. When grown on R2A medium at 25 & DEG;C, strain 13-115(T) formed round, convex and white colonies. This strain showed growth at temperatures ranging from 10 to 30 & DEG;C and tolerated a pH range of 6-9. The strain could also tolerate NaCl concentrations up to 5%. Analysis of the 16S rRNA gene sequence revealed that strain 13-115(T) exhibited similarity of over 99% with Pectobacterium brasiliense, P. carotovorum, P. polaris, and P. parvum. By conducting multilocus sequence analyses using dnaX, leuS, and recA genes, a separate phylogenetic lineage was discovered between strain 13-115(T) and other members of the genus Pectobacterium. Moreover, the strain showed relatively low in silico DNA-DNA hybridization (<60.6%) and average nucleotide identity (ANI) (<94.9%) values with recognized Pectobacterium species. The isolate has a genome size of 5,069,478 bp and a genomic G + C content of 52.04 mol%. Major fatty acids identified in the strain included C-16:0 (28.99%), summed feature 3 (C-16:1 & omega;7c and/or C-16:1 & omega;6c; 28.85%), and C-18:1 & omega;7c (19.01%). Pathogenicity assay confirmed that the novel strain induced soft rot symptoms in cucumber plants and Koch's postulates were fulfilled. Molecular analysis and phenotypic data indicated that strain 13-115(T) could be classified as a new species within the Pectobacterium genus, which has been named Pectobacterium jejuense. The type strain is 13-115(T) (= KCTC 92800(T) = JCM 35940(T)).

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