Enterobacter muelleri sp nov., isolated from the rhizosphere of Zea mays

A beige-pigmented, oxidase-negative bacterial strain (JM-458(T)), isolated from a rhizosphere sample, was studied using a polyphasic taxonomic approach. Cells of the isolate were rod-shaped and stained Gram-negative. A comparison of the 16S rRNA gene sequence of strain JM-458(T) with sequences of the type strains of closely related species of the genus Enterobacter showed that it shared highest sequence similarity with Enterobacter mori (98.7 %), Enterobacter hormaechei (98.3 %), Enterobacter cloacae subsp. dissolvens, Enterobacter ludwigii and Enterobacter asburiae (all 98.2 %). 16S rRNA gene sequence similarities to all other Enterobacter species were below 98 %. Multilocus sequence analysis based on concatenated partial rpoB, gyrB, infB and atpD gene sequences showed a clear distinction of strain JM-458(T) from its closest related type strains. The fatty acid profile of the strain consisted of C-16 : 0, C-17 : 0 cyclo, iso-C-15 : 0 2-OH/C-16 : 1 omega 7c and C-18 : 1 omega 7c as major components. DNA-DNA hybridizations between strain JM-458(T) and the type strains of E. mori, E. hormaechei and E. ludwigii resulted in relatedness values of 29 % (reciprocal 25 %), 24 % (reciprocal 43 %) and 16 % (reciprocal 17 %), respectively. DNA-DNA hybridization results together with multilocus sequence analysis results and differential biochemical and chemotaxonomic properties showed that strain JM-458(T) represents a novel species of the genus Enterobacter, for which the name Enterobacter muelleri sp. nov. is proposed. The type strain is JM-458(T) (=DSM 29346(T)=CIP 110826(T)=LMG 28480(T)=CCM 8546(T)).