Zoogloea dura sp. nov., a N2-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-4-1-14T, was obtained from forest soil sampled at Gwanggyo mountain, Gyeonggi-do, Republic of Korea. Cells were colourless, aerobic, grew optimally at 28–35 °C and hydrolysed DNA and casein. Phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain G-4-1-14T formed a lineage within the genus Zoogloea . The closest members were Zoogloea resiniphila ATCC 70068T (98.6 % sequence similarity), Zoogloea caeni EMB43T (98.2 %), Zoogloea oryzae A-7T (97.7 %), Zoogloea ramigera IAM 12136T (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-C15 :0 2-OH/C16  : 1 ω7c) and C16 : 0. The DNA G+C content was 65.9 mol%. The average nucleotide identity and digital DNA–DNA hybridization relatedness values between strain G-4-1-14T 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-4-1-14T represents a novel species in the genus Zoogloea , for which the name Zoogloea dura sp. nov. is proposed. The type strain is G-4-1-14T (=KACC 21618T=NBRC 114358T). In addition, we propose emendation of the genus Zoogloea and the species Zoogloea oryzae and Zoogloea ramigera .