Clostridium nitrophenolicum sp. nov., a novel anaerobic p-nitrophenol-degrading bacterium, isolated from a subsurface soil sample.

An obligate anaerobic, mesophilic, motile and endospore-forming bacterium, designated 1D(T), was isolated from a subsurface soil sample. The young culture of strain 1D(T) was Gram-positive and formed oval spores that were central in position. Based on the biochemical, chemotaxonomic and physiological data, strain 1D(T) appears to be a member of the genus Clostridium. Strain 1D(T) was found to be capable of degrading p-nitrophenol (pNP) at a concentration of 0.5 mM under anaerobic conditions as revealed by HPLC analysis. The major fatty acids were C(16 : 0 )(28.02 %), iso-C(17 : 1) I/anteiso B (23.05 %) and C(14 : 0) (10.02 %). The major polar lipid content was diphosphatidylglycerol. Strain 1D(T) showed highest 16S rRNA gene sequence similarity to Clostridium aciditolerans JW/YJL-B3(T) (98.2 %) and similarity was less for Clostridium scatologenes ATCC 25775(T) (95.1 %), Clostridium drakei SL1(T) (95.0 %) and Clostridium carboxidivorans P7(T) (95.0 %). Phylogenetic analysis showed that it formed a coherent cluster with the species belonging to cluster I of the genus Clostridium. The DNA G+C content was 35.5 mol%. DNA-DNA hybridization analysis indicated a mean value of 36.4 % between strain 1D(T) and its closest relative C. aciditolerans. Several phenotypic differences from the closely related species were also revealed. On the basis of the polyphasic characteristics, strain 1D(T) represents a novel species of the genus Clostridium, for which the name Clostridium nitrophenolicum sp. nov. is proposed. The type strain is 1D(T) (=MTCC 7832(T)=JCM 14030(T)).