A microbial consortium led by a novel Pseudomonas species enables degradation of carbon tetrachloride under aerobic conditions

Abstract

Carbon tetrachloride (CT) is a recalcitrant and high priority pollutant known for its toxicity, environmental prevalence, and inhibitory activities. Although much is known about anaerobic CT biodegradation, microbial degradation of CT under aerobic conditions has not yet been reported. This study reports for the first time the enrichment of a stable aerobic CT-degrading bacterial consortium, from a CT-contaminated groundwater sample, capable of co-metabolically degrading 30 μM of CT within a week. A Pseudomonas strain (designated as Stari2) that is the predominant bacterium in this consortium was isolated, and further characterization showed that this bacterium can tolerate and co-metabolically degrade up to 5 mM of CT under aerobic conditions in the presence of different carbon/energy sources. The CT biodegradation profiles of strain Stari2 and the consortium were found to be identical, while no significant positive correlation between strain Stari2 and other bacteria was observed in the consortium during the period of higher CT biodegradation. These results confirmed that the isolated Pseudomonas strain Stari2 is the key player in the consortium catalyzing the biodegradation of CT. No chloroform (CF) or other chlorinated compound was detected during the cometabolism of CT. The whole genome sequencing of strain Stari2 showed that it is a novel Pseudomonas species. The findings demonstrated that biodegradation of CT under aerobic conditions is feasible, and the isolated CT-degrader Pseudomonas sp. strain Stari2 has a great potential for in-situ bioremediation of CT-contaminated environments.

Keywords: Aerobic biodegradation; Bioremediation; Carbon tetrachloride; Co-metabolism; Microbial consortia; Pseudomonas.