Pectobacterium jejuense sp. nov. Isolated from Cucumber Stem Tissue

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 °C, strain 13-115 T formed round, convex and white colonies. This strain showed growth at temperatures ranging from 10 to 30 °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 ω 7 c and/or C 16:1 ω 6 c ; 28.85%), and C 18:1 ω 7 c (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 ).