Intrasporangium zincisolvens sp. nov., A Novel Actinobacterium Isolated from Rhizosphere Soil.

Abstract

A novel phosphate-solubilizing and zinc-solubilizing actinobacterium strain YIM S08009^T was isolated from rhizosphere soil collected from Pinus yunnanensis in Wuliangshan National Nature Reserve, Pu'er City, Yunnan Province, southwest PR China. Cells of strain YIM S08009^T were Gram-stain-positive, non-motile, irregular rods to cocci, and formed yellow and white colonies on nutrient agar. Growth was observed at 10-40 °C (optimum 25-35 °C), pH 6.0-8.5 (optimum 7), and 0-4% (w/v) NaCl (optimum 1%). The cell wall peptidoglycan contained LL-diaminopimelic acid. The whole-cell sugars were mannose, ribose, glucose, and galactose. The predominant menaquinone was MK-8(H₄). Major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, unknown lipid, and 3 unknown phospholipids. The predominant fatty acids were iso-C_14:0, iso-C_15:0, and iso-C_16:0. The DNA G + C content was 72.6%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM S08009^T belonged to genus Intrasporangium, and was most closely related to Intrasporangium flavum MUSC 78^T, with 99.0% 16S rRNA gene sequence similarity. Strain YIM S08009^T shared 90.1% orthologous average nucleotide identity (OrthoANI) and 39.8% digital DNA-DNA hybridization (dDDH) with I. flavum MUSC 78^T. The genome of strain YIM S08009^T contained phosphate-solubilizing genes (SenX3, RegX3, pstSCAB, ugpBAEC, phoA) and zinc-solubilizing genes (znuABC, zupT), and the strain had also demonstrated in vitro phosphorus and zinc solubilization. Based on the genotypic and phenotypic analyses, strain YIM S08009^T (= CGMCC 1.60168^T = NBRC 116604^T = KCTC 59021^T) represents a novel Intrasporangium species, for which the name Intrasporangium zincisolvens sp. nov. is proposed.