Characterization and genome functional analysis of an efficient nitrile-degrading bacterium, Rhodococcus rhodochrous BX2, to lay the foundation for potential bioaugmentation for remediation of nitrile-contaminated environments

Nitriles are a class of extremely toxic chemicals with extensive applications, and these compounds pose potential risks to humans and ecosystems. The activated sludge isolate Rhodococcus rhodochrous BX2 efficiently metabolizes aliphatic nitriles. However, the molecular underpinnings of the degradation mechanism of aliphatic nitriles by BX2 remain unknown, and the metabolic fate of aliphatic nitriles also has not been elucidated. Here, strain BX2 was capable of completely mineralizing three aliphatic nitriles. Bioinformatic analysis yielded a deeper insight into the genetic basis of BX2 for efficient degradation of aliphatic nitriles and adaptation to harsh environments. Transcriptional, enzyme activity and metabolite analyses confirmed that the intracellular inducible nitrile hydratase/amidase pathway is the preferred metabolic pathway. Our findings provide an in-depth understanding of the environmental fate of aliphatic nitriles and, most importantly, offer a new perspective on the potential applications of the genus Rhodococcus in bioremediation and the development of degradation enzyme resources.