Gordonia crocea sp. nov. and Gordonia spumicola sp. nov. isolated from sludge of a wastewater treatment plant

Abstract

Two novel actinobacteria, designated NBRC 107696^T and NBRC 107697^T, were isolated from sludge samples from a wastewater treatment plant and their taxonomic positions were investigated by a polyphasic approach. The cells of the strains were aerobic, rod-shaped, non-motile and non-endospore-forming. The strains contained glutamic acid, alanine and <i>meso</i>-diaminopimelic acid in the peptidoglycan. Galactose and arabinose were detected as cell-wall sugars. The predominant menaquinone was identified as MK-9(H₂) and the major fatty acids were C_{16 : 0}, C_{18 : 1}ω9c and C_{16 : 1}ω7c. The DNA G+C contents of NBRC 107696^T and NBRC 107697^T were 68.07 and 68.99 mol%, respectively. Phylogenetic analyses based on 16S rRNA gene sequence comparisons revealed that NBRC 107696^T and NBRC 107697^T were a clade with members of the genus <i>Gordonia</i>. The highest 16S rRNA gene sequence similarity values were obtained with <i>Gordonia araii</i> IFM 10211^T (98.9 %) for NBRC 107697^T, and <i>Gordonia malaquae</i> IMMIB WWCC-22^T, <i>Gordonia neofelifaecis</i> AD-6^T and <i>Gordonia humi</i> CC-12301^T (98.1 %) for NBRC 107696^T, respectively. The digital DNA-DNA relatedness data coupled with the combination of genotypic and phenotypic data indicated that the two strains are representatives of two novel separate species. The names proposed to accommodate these two strains are <i>Gordonia spumicola</i> sp. nov. and <i>Gordonia crocea</i> sp. nov., and the type strains are NBRC 107696^T (=IFM 10067^T=TBRC 11239^T) and NBRC 107697^T (=IFM 10881^T=TBRC 11240^T), respectively.