Cyanate Assimilation by the Alkaliphilic Cyanide-Degrading Bacterium Pseudomonas pseudoalcaligenes CECT5344: Mutational Analysis of the cyn Gene Cluster

• Published in: International journal of molecular sciences Vol. 20; no. 12; p. 3008
• Main Authors: Sáez, Lara Paloma, Cabello, Purificación, Ibáñez, María Isabel, Luque-Almagro, Víctor Manuel, Roldán, María Dolores, Moreno-Vivián, Conrado
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 20.06.2019; MDPI
• Subjects: Aerobic microorganisms; Alternative oxidase; Ammonia; Ammonia-oxidizing bacteria; Ammonium; Assimilation; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bicarbonates; Biodegradation, Environmental; Biological assimilation; Carbon dioxide; Carbon-Nitrogen Lyases - genetics; Carbon-Nitrogen Lyases - metabolism; Carbonic anhydrase; Cofactors; Contaminants; cyanase; cyanate; Cyanates; Cyanates - metabolism; cyanide; Cyanides; Cyanides - metabolism; Cytochrome-c oxidase; Detoxification; Electron transport; Electron transport chain; Enzymes; Genes; Genomes; Jewelry; Jewelry industry; jewelry residue; Metabolism; Microorganisms; Multigene Family; nitrate; Nitriles; nitrite; Nitrogen; Organic chemistry; Oxidase; Oxidation; Pseudomonas pseudoalcaligenes; Pseudomonas pseudoalcaligenes - genetics; Pseudomonas pseudoalcaligenes - metabolism; Waste Water - analysis; Waste Water - microbiology; cyanate; nitrite; Pseudomonas pseudoalcaligenes; jewelry residue; cyanide; nitrate; cyanase
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms20123008

The alkaliphilic bacterium CECT5344 can grow with cyanate, cyanide, or cyanide-containing industrial residues as the sole nitrogen source, but the assimilation of cyanide and cyanate takes place through independent pathways. Therefore, cyanide degradation involves a chemical reaction between cyanide and oxaloacetate to form a nitrile that is hydrolyzed to ammonium by the nitrilase NitC, whereas cyanate assimilation requires a cyanase that catalyzes cyanate decomposition to ammonium and carbon dioxide. The CECT5344 gene cluster codes for the putative transcriptional regulator CynF, the ABC-type cyanate transporter CynABD, and the cyanase CynS. In this study, transcriptional analysis revealed that the structural genes constitute a single transcriptional unit, which was induced by cyanate and repressed by ammonium. Mutational characterization of the genes indicated that CynF was essential for gene expression and that nitrate/nitrite transporters may be involved in cyanate uptake, in addition to the CynABD transport system. Biodegradation of hazardous jewelry wastewater containing high amounts of cyanide and metals was achieved in a batch reactor operating at an alkaline pH after chemical treatment with hydrogen peroxide to oxidize cyanide to cyanate.