A Gram-negative, rod-shaped bacterium was isolated from a mixed culture that degraded tert-butyl alcohol (TBA) in a granular-activated carbon (GAC) sample from a Biological-GAC reactor. Strain YZ2T was assigned to the Betaproteobacteria within the family Comamonadaceae based on 16S rRNA gene similarities. The nearest phylogenetic relative (95.0 % similarity) with a valid name was Hydrogenophaga taeniospiralis. The DNA G+C content was 66.4 mol%. DNA:DNA hybridization indicated that the level of relatedness to members of the genus Hydrogenophaga ranged from 1.1 to 10.8 %. The dominant cellular fatty acids were: 18:1 w7c (75 %), 16:0 (4.9 %), 17:0 (3.85 %), 18:0 (2.93 %), 11 methyl 18:1 w7c (2.69 %), Summed Feature 2 (2.27 %), and 18:0 3OH (1.35 %). The primary substrate used was TBA, which is a fuel oxygenate and groundwater contaminant. YZ2T was non-motile, without apparent flagella. It is a psychrotolerant, facultative aerobe that grew between pH 6.5 and 9.5, and 4 and 30 C. The culture grew on and mineralized TBA at 4 C, which is the first report of psychrotolerant TBA degradation. Hydrogen was used as an alternative electron donor. The culture also grew well in defined freshwater medium with ethanol, butanol, hydroxy isobutyric acid, acetate, pyruvate, citrate, lactate, isopropanol, and benzoic acid as electron donors. Nitrate was reduced with hydrogen as the sole electron donor. On the basis of morphological, physiological, and chemotaxonomic data, a new species, Hydrogenophaga carboriunda is proposed, with YZ2T as the type strain.
Bibliographical noteFunding Information:
This work was funded by British Petroleum, an Atlantic Richfield Company (BP/ARCO); we thank Xiaomin Yang of BP/ARCO for providing the GAC samples. We thank Rachel Whitaker and Angela Kent of the University of Illinois (Microbiology and Natural Resources, respectively) for suggestions regarding phylogenetic analyses. We also thank Cate Wallace of the Imaging Technology Group of Beckman Institute for Advanced Science and Technology at the University of Illinois and Lou Ann Miller of the University of Illinois for SEM microscopy and cell culture preparation for SEM.