Genomic Characterization of Isolated from Mine Tailings in Peru and Evaluation of Its Cyanide-Degrading Enzyme CynD.

Understanding the biochemistry and metabolic pathways of cyanide degradation is necessary to improve the efficacy of cyanide bioremediation processes and industrial requirements. We have isolated and sequenced the genome of a cyanide-degrading strain from water in contact with mine tailings from Lima, Peru. This strain was classified as Bacillus safensis based on 16S rRNA gene sequencing and core genome analyses and named B. safensis PER-URP-08. We searched for possible cyanide-degradation enzymes in the genome of this strain and identified a putative cyanide dihydratase (CynD) gene similar to a previously characterized CynD from Bacillus pumilus C1. Sequence analysis of CynD from and allow us to identify C-terminal residues that differentiate both CynDs. We then cloned, expressed in Escherichia coli, and purified recombinant CynD from PER-URP-08 (CynD) and showed that in contrast to CynD from C1, this recombinant CynD remains active at up to pH 9. We also showed that oligomerization of CynD decreases as a function of increased pH. Finally, we demonstrated that transcripts of CynD in PER-URP-08 are strongly induced in the presence of cyanide. Our results suggest that the use of PER-URP-08 and CynD as potential tool for cyanide bioremediation warrants further investigation. Despite being of environmental concern around the world due to its toxicity, cyanide continues to be used in many important industrial processes. Thus, searching for cyanide bioremediation methods is a matter of societal concern and must be present on the political agenda of all governments. Here, we report the isolation, genome sequencing and characterization of cyanide degradation capacity of a bacterial strain isolated from an industrial mining site in Peru. We characterize a cyanide dehydratase (CynD) homolog from one of these bacteria, Bacillus safensis PER-URP-08.