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

Abstract

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}ω7 c and C _{18 : 1}ω7 c 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).