Sphingomonas oryzagri sp. nov., isolated from a rice field

Abstract

A Gram-stain-negative, aerobic, short rod-shaped and motile novel bacterial strain, designated MAHUQ-71(T), was isolated from the soil of a rice field. The colonies were observed to be milky yellow-coloured, smooth, spherical and 0.1-0.4 mm in diameter when grown on Reasoner's 2A agar medium for 2 days. Strain MAHUQ-71(T) was found to be able to grow at 15-37 degrees C, pH 5.0-10.0 and with 0-3.0% NaCl (w/v). The strain was found to be positive for the catalase test, but negative for the oxidase test. The strain was positive for hydrolysis of aesculin and Tween 20. According to the 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Sphingomonas and to be closely related to Sphingomonas chungangi MAH-6(T) (98.5 % sequence similarity), Sphingomonas polyaromaticivorans B2-7(T) (98.4%) and Sphingomonas oligoaromativorans SY-6(T) (96.6%). Strain MAHUQ-71(T) has a draft genome size of 4255278 bp (10 contigs), annotated with 4098 protein-coding genes, 47 tRNA and three rRNA genes. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain MAHUQ-71(T) and the closest type strain S. chungangi MAH-6(T) were in the range of 85.6 and 30.6 %, respectively. The genomic DNA G+C content was determined to be 66.7 mol%. The predominant isoprenoid quinone was ubiquinone 10. The major fatty acids were identified as summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c), C-16:0 and C-14:0 2OH. The main polar lipids were phosphatidylcholine, phosphatidylethanolamine, diphosphatidylglycerol and sphingoglycolipid. On the basis of dDDH and ANI values, as well as the results of genotypic, chemotaxonomic and physiological analyses, strain MAHUQ-71(T) represents a novel species within the genus Sphingomonas, for which the name Sphingomonas oryzagri sp. nov. is proposed, with MAHUQ-71(T) (=KACC 22252(T)=CGMCC 1.19065(T)) as the type strain.