Leucobacter chinensis sp. nov., with plant growth-promoting potential isolated from field soil after seven-years continuous maize cropping

Abstract

A novel Gram-stain-positive, aerobic, non-motile and rod-shaped bacterium, designated strain NC76-1T, was isolated from soil from a field that had undergone seven years continuous maize cropping from Liuba town located in Zhangye city, Gansu province, PR China. Colonies of strain NC76-1T were white, opaque and circular with a convex shape. The isolate was found to be able to grow at 10–40 °C (optimum 30 °C), pH 6.0 to 12.0 (optimum 7.0–8.0) and with 0–5.0 % (w/v) NaCl (optimum 0%). On the basis of the results of 16S rRNA gene sequence analysis, the strain fell within the clade of the genus Leucobacter , showing the highest sequence similarities with Leucobacter iarius 40T (97.4%), Leucobacter aridicollis CIP 108388T (97.0%), Leucobacter chromiireducens subsp. solipictus TAN 31504T (96.7%) and Leucobacter denitrificans M1T8B10T (96.7%). The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between NC76-1T and its closest relatives, L. iarius 40T, L. aridicollis CIP 108388T, L. chromiireducens subsp. solipictus TAN 31504T and L. denitrificans M1T8B10T were ≤73.5 % and 20.3%, respectively. The genomic DNA G+C content of NC76-1T was 61.5 mol%. It presented MK-11 as the predominant menaquinone. The major cellular fatty acids were anteiso-C15 : 0 (49.2 %) and iso-C16 : 0 (35.7%). The major polar lipids were found to be diphosphatidyglycerol, phosphatidylglycerol, phosphatidylethanolamine, aminoglycolipid, five glycolipid and one unidentified lipids. The cell wall amino acids were 2,4-diaminobutyric acid, alanine, glutamic acid, glycine and threonine. On the basis of the phylogenetic, phenotypic and chemotaxonomic characteristics, strain NC76-1T is concluded to represent a novel species within the genus Leucobacter , for which the name Leucobacter chinensis sp. nov. is proposed. The type strain is NC76-1T (GDMCC 1.2286T= JCM 34651T).