Trujillonella humicola sp. nov., a siderophore-synthesizing bacterium isolated from black soil in Northeast China

Abstract

A Gram-stain-positive, motile, and oval-shaped bacterium, designated as SYSU BS000539^T, was isolated from black soil in Heilongjiang Province, China. 16S rRNA gene sequencing revealed that the isolate shared the highest similarity to Trujillonella endophytica DSM 45413^T (98.32%), and phylogenetic analysis confirmed that it belonged to the genus Trujillonella. The strain could grow at temperatures from 15 to 37 °C (with an optimum at 28 °C), in salt concentrations of 0–5% (w/v) (with an optimum at 0%), and at pH levels from 6.0 to 10.0 (with an optimum at 8.0). The dominant cellular fatty acids (> 5%) were iso-C_16:0, iso-C_15:0, and iso-C_16:1, while the principal respiratory quinones was menaquinone MK-9 (H₄) with menaquinone MK-8 as minor components. Polar lipids were composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol methylphosphonolipid, an unidentified aminolipid and two unidentified polar lipids. The G + C content of the genome was 74.97%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SYSU BS000539^T and T. endophytica DSM 45413^T were 84.10% and 27.60%, respectively, falling below species delineation thresholds. Combining phylogenetic, genotypic, chemotaxonomic, physiological and biochemical analyses, it is evident that SYSU BS000539^T represented a novel species within the genus Trujillonella, for which the name Trujillonella humicola sp. nov. is proposed. The type strain of the proposed novel species is SYSU BS000539^T (= MCCC 1K09330^T = KCTC 59402^T).