Comparative genomic analysis of the genus Novosphingobium and the description of two novel species Novosphingobium aerophilum sp. nov. and Novosphingobium jiangmenense sp. nov.

Members of the genus Novosphingobium are well known for their metabolically versatile and great application potential in pollution elimination. The three novel bacterial strains, designated 4Y4T, 4Y9, and 1Y9AT, were isolated from aquaculture water and characterized by using a polyphasic taxonomic approach. The 16S rRNA gene sequences phylogenetic analysis revealed that the three strains belonged to the genus Novosphingobium. The phylogenomic analysis indicated that the three strains formed two independent and robust branches distinct from all reference strains. The analyses of dDDH values and ANIs between the three strains and their relatives further demonstrated that the three strains represented two different novel genospecies. Comparative genomic analysis of the three isolates and 32 type strains of the genus Novosphingobium showed that the most important central metabolic pathways of these strains appeared to be similar, while specific and specialized metabolic pathways were flexible and variable among these strains. Chemotaxonomic characterization exhibited that the predominant cellular fatty acids were summed feature 8, summed feature 3, and C14:0 2OH; the major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylglycerol, and sphingoglycolipid; the major respiratory quinone and polyamine were Q-10 and spermidine. The DNA G + C contents were 67.6 and 64.7 %. Based on the genotypic and phenotypic characteristics, strains 4Y4T and 1Y9AT are concluded to represent two novel species of the genus Novosphingobium, for which the names Novosphingobium aerophilum sp. nov. (type strain 4Y4T = GDMCC 1.1828 T = KACC 21946 T) and Novosphingobium jiangmenense sp. nov. (type strain 1Y9AT = GDMCC 1.1936 T = KACC 22085 T) are proposed.

Hymenobacter metallilatus sp. nov., isolated from abandoned lead-zinc ore.

An aerobic, non-motile, Gram-stain-negative, red-to-pinkish and rod-shaped bacterium, designated 9PBR-2T, was isolated from an abandoned lead-zinc ore sample collected from Meizhou, Guangdong Province, PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 9PBR-2T belongs to the genus Hymenobacter and was most closely related to Hymenobacter rigui KCTC 12533T (98.0 %), Hymenobacter swuensis KCTC 32018T (97.8 %) and Hymenobacter perfusus LMG 26000T (97.6 %). The calculated average nucleotide identity values based on whole genome sequences between strain 9PBR-2T and closely related type strains ranged from 81.3 to 84.1 %. Correspondingly, the digital DNA-DNA hybridization values ranged from 25.5 to 28.1 %. The major fatty acids of strain 9PBR-2T were iso-C15:0, anteiso-C15:0, C16:1ω5c, summed feature 3 (C16:1ω6c and/or C16:1ω7c) and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). It contained menaquinone 7 (MK-7) as the major isoprenoid quinone and phosphatidylethanolamine as the major polar lipid. The genomic DNA G+C content based on whole genome sequence was 59.8 mol%. Characterization based on phylogenetic, chemotaxonomic and phenotypic analyses clearly indicated that strain 9PBR-2T represents a novel species of the genus Hymenobacter, for which the name Hymenobactermetallilatus sp. nov. is proposed. The type strain is 9PBR-2T (=GDMCC 1.1492T=JCM 32699T).