The aim of this study is to review the current state of and highlight the challenges in the production of microbial nitrilases as catalysts for the mild hydrolysis of industrially important nitriles. Together with aldoxime dehydratase, the nitrile-hydrolyzing enzymes (nitrilase, nitrile hydratase) are key enzymes in the aldoxime-nitrile pathway which is widely distributed in bacteria and fungi. The availability of nitrilases has grown significantly over the past decade due to the use of metagenomic and database-mining approaches. Databases contain plenty of putative enzymes of this type, whose overproduction may improve the spectrum and the industrial utility of nitrilases. By exploiting this resource, the number of experimentally verified nitrilases has recently increased to several hundred. We especially focus on the efficient heterologous expression systems that are applicable for the overproduction of wild-type nitrilases and their artificial variants. Biocatalyst forms with industrial potential are also highlighted. The potential industrial applications of nitrilases are classified according to their target products (α-hydroxy acids, α- and β-amino acids, cyano acids, amides). The emerging uses of nitrilases and their subtypes (cyanide hydratases, cyanide dihydratases) in bioremediation is also summarized. The integration of nitrilases with other enzymes into artificial multienzymatic and chemoenzymatic pathways is considered a promising strategy for future applications.

• Keywords
• Aldoxime–nitrile pathway, Biocatalytic applications, Database mining, Heterologous production, Metagenome mining, Nitrilase,
• MeSH
• Aminohydrolases genetics   metabolism   MeSH
• Bacteria enzymology   genetics   MeSH
• Bacterial Proteins genetics   metabolism   MeSH
• Biodegradation, Environmental MeSH
• Biocatalysis MeSH
• Databases, Protein MeSH
• Fungal Proteins genetics   metabolism   MeSH
• Fungi enzymology   genetics   MeSH
• Metagenomics MeSH
• Nitriles metabolism   MeSH
• Protein Engineering methods   MeSH
• Recombinant Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Aminohydrolases MeSH
• Bacterial Proteins MeSH
• Fungal Proteins MeSH
• nitrilase MeSH Browser
• Nitriles MeSH
• Recombinant Proteins MeSH