Neoroseomonas alba sp. nov., Neoroseomonas nitratireducens sp. nov., Paraoseomonas indoligenes sp. nov and Paraoseomonas baculiformis sp. nov., isolated from the rhizosphere of paddy soil

Abstract

Four novel Gram-stain negative bacteria, designated as HAJ6(T), PWR1(T), SG15(T) and SSH11(T), were isolated from the soil sample of paddy fields from Goyang in the Republic of Korea. The isolated strains were aerobic, short-rod or rod shaped, non-sporulating. They grew optimally at 30 & DEG;C, pH 7 and without additional NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that they belong to the genus of Neoroseomonas and Pararoseomonas and closely relate to Neoroseomonas terrae DS-48(T) (97.5%; HJA6(T)), Neoroseomonas rubea MO17(T) (99.4%; PWR1(T)), Pararoseomonas pecuniae N75(T) (97.3%; SG15(T)) and Pararoseomonas rosea 173-96(T) (97.8%; SSH11(T)). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of the isolates with the most closely related strains were 72.9-90.9% and 19.1-42.5%, respectively. The major fatty acids in the isolates were C-16:0, C-19:0 cyclo & omega;8c, C-18:1 2-OH and summed feature 8 (composed of C-18:1 & omega;7c and/or C-18:1 & omega;6c), and the predominant quinone was ubiquinone 10. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, and other unidentified polar lipids. Based on the draft genome sequences, the genomic DNA G + C content of HAJ6(T), PWR1(T), SG15(T) and SSH11(T) were 69.5%, 72.0%, 70.8% and 69.7%, respectively. All isolates produced indole-3-acetic acid (IAA), a type of plant growth hormone in the presence of (L)-tryptophan. Physiological and biochemical tests and 16S rRNA sequence analysis clearly revealed that the isolates were novel species belonging to the genus Neoroseomonas and Pararoseomonas. Their proposed names were as follows: Neoroseomonas alba sp. nov. for strain HJA6(T) (= KACC 21545(T) = NBRC 114316(T)), Neoroseomonas nitratireducens sp. nov. for strain PWR1(T) (= KCTC 82687(T) = NBRC 114490(T)), Pararoseomonas indoligenes sp. nov. for strain SG15(T) (= KCTC 82686(T) = NBRC 114481(T)) and Paraoseomonas baculiformis sp. nov. for strain SSH11(T) (= KCTC 82685(T) = NBRC 11482(T)).