Characterization and genetic determination of a newly isolated cotinine-degrading bacterium Terrabacter sp. strain cot-2 from synergistic consortium

Cotinine, the main metabolite of nicotine, was frequently detected in aquatic environment and pose a high risk to environmental safety and human health. Microbial degradation was considered as the most effective and environmental-friendly method for cotinine elimination. However, the microbial resources including bacterial consortia and pure cultures were limited. In this study, a synergistic consortium involved in cotinine degradation was successfully obtained and metagenomic analysis were investigated to reveal the key microorganisms responsible for cotinine and 6-hydroxy-3-succinoylpyridine (HSP) degradation, respectively. The genes encoding for cotinine hydroxylation (cotA1A2A3) and for HSP cleavage (hspB) were successfully amplified from the consortium C2 and functionally identified. Furthermore, a new cotinine-degrading pure culture strain, Terrabacter sp. cot-2, was isolated from the consortium C2. The degradation characterization and key intermediates of cotinine by strain cot-2 were analyzed. Then, the complete genome of strain cot-2 was determined and the gene cluster cot was demonstrated to be widely distributed in different environments. This study significantly broadened the knowledge on the degradation of the functional consortium and mechanism involved in cotinine biodegradation at molecular level, which also offering a promising solution to mitigate the impact of cotinine in aquatic ecosystems.