Microbial Transformation of Nitriles to High-Value Acids or Amides

Abstract

Biotransformation of nitriles mediated by nitrile-amide converting enzymes has attracted considerable attention and developed tremendously in the recent years in China since it offers a valuable alternative to traditional chemical reaction which requires harsh conditions. As a result, an upsurge of these promising enzymes (including nitrile hydratase, nitrilase and amidase) has been taking place. This review aims at describing these enzymes in detail. A variety of microorganisms harboring nitrile-amide converting activities have been isolated and identified in China, some of which have already applied with moderate success. Currently, a wide range of high-value compounds such as aliphatic, alicyclic, aromatic and heterocyclic amides and their corresponding acids were provided by these nitrile-amide degrading organisms. Simultaneously, with the increasing demand of chiral substances, the enantioselectivity of the nitrilase superfamily is widely investigated and exploited in China, especially the bioconversion of optically active alpha-substituted phenylacetamides, acids and 2,2-dimethylcyclopropanecarboxamide and 2,2-dimethylcyclopropanecarboxylic acid by means of the catalysts exhibiting excellent stereoselectivity. Besides their synthetic value, the nitrile-amide converting enzymes also play an important role in environmental protection. In this context, cloning of the genes and expression of these enzymes are presented. In the near future in China, an increasing number of novel nitrile-amide converting organisms will be screened and their potential in the synthesis of useful acids and amides will be further exploited.

Enantioselective biocatalytic hydrolysis of (R,S)-mandelonitrile for production of (R)-(−)-mandelic acid by a newly isolated mutant strain

“…Some nitrilases have been investigated for the preparation of single enantiomers of carboxylic acids. One of the most important application appears to be the biotransformation of racemic mandelonitrile to produce chiral R-MA [3]. Several bacteria such as A. faecalis ATCC 8750 [20], Pseudomonas putida MTCC 5110 [8], and Alcaligenes sp.…”

“…Although a number of microorganisms with nitrilases that can catalyze the formation of carboxylic acids from the corresponding nitriles have been isolated and identified [3], there are only a few reports of microorganisms with nitrilases which can catalyze the formation of R-MA from (R,S)-mandelonitrile [6,8,20]. Moreover, the nitrilases from these strains are not satisfactory because of their relatively poor nitrilase activity or stability; thus most of them are not suitable to be applied in industrial process.…”

Characterization of an enantioselective amidase with potential application to asymmetric hydrolysis of (R, S)-2, 2-dimethylcyclopropane carboxamide

“…Recently, amidase (EC 3.5.1.4) has become a promising synthesis tool for the production of valuable chiral amides and their derivatives due to its excellent enantioselectivity and environmental compatibility (Banerjee et al 2002;Chen et al 2009;Kobayashi and Shimizu 2000).…”

Enantioselective hydrolysis of (R)-2, 2-dimethylcyclopropane carboxamide by immobilized cells of an R-amidase-producing bacterium, Delftia tsuruhatensis CCTCC M 205114, on an alginate capsule carrier

“…Production of economically important chiral carboxyl acid and its amide derivatives by biotransformation of nitrile using nitrile-converting enzymes (nitrile hydratase, amidase and nitrilase) has become a promising chiral synthesis method [3,5,14,15,[18][19][20]33]. With the ability to hydrolyze amides to corresponding optical pure compounds with high enantioselectivity, mild reaction conditions and environmental compatibility, amidases (EC 3.5.1.4) have been intensively studied [2,4,7,8,10,12,13,16,17,21,22,26,30].…”