Zoogloea dura sp. nov., a N-2-fixing bacterium isolated from forest soil and emendation of the genus Zoogloea and the species Zoogloea oryzae and Zoogloea ramigera

Abstract

A motile, Gram-stain-negative, rod-shaped bacterium, designated G-4-1-14(T), was obtained from forest soil sampled at Gwanggyo mountain, Gyeonggi-do, Republic of Korea. Cells were colourless, aerobic, grew optimally at 28-35 degrees C and hydrolysed DNA and casein. Phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain G-4-1-14(T) formed a lineage within the genus Zoogloea. The closest members were Zoogloea resiniphila ATCC 70068(T) (98.6% sequence similarity), Zoogloea caeni EMB43(T) (98.2 %), Zoogloea oryzae A-7(T) (97.7%), Zoogloea ramigera IAM 12136(T) (96.9 %) and Zoogloea oleivorans BucT (96.2%). The major respiratory quinone was ubiquinone-8 and the principal polar lipids were phosphatidylethanolamine, phosphatidyl-N-methylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The predominant cellular fatty acids were summed feature 3 (iso-C-15:0 2-OH/C-16:1 omega 7c) and C-16:0. The DNA G+C content was 65.9 mol%. The average nucleotide identity and digital DNA-DNA hybridization relatedness values between strain G-4-1-14(T) and other type strains were <= 81.6 and <= 24.9%, respectively, which are below the species demarcation thresholds. Based on the results of phenotypic, phylogenetic and genomic analyses, strain G-4-1-14(T) represents a novel species in the genus Zoogloea, for which the name Zoogloea dura sp. nov. is proposed. The type strain is G-4-1-14(T) (=KACC 21618(T)=NBRC 114358(T)). In addition, we propose emendation of the genus Zoogloea and the species Zoogloea oryzae and Zoogloea ramigera.