title: Hydrolysis of nitriles by soil bacteria: variation with soil origin.
abstract: OBJECTIVE
  The aim of this study was to explore bacterial soil diversity for nitrile biocatalysts, in particular, those for hydrolysis of β-substituted nitriles, to the corresponding carboxamides and acids that may be incorporated into peptidomimetics. To achieve this, we needed to compare the efficiency of isolation methods and determine the influence of land use and geographical origin of the soil sample.
  
  
  RESULTS
  Nitrile-utilizing bacteria were isolated from various soil environments across a 1000 km long transect of South Africa, including agricultural soil, a gold mine tailing dam and uncultivated soil. The substrate profile of these isolates was determined through element-limited growth studies on seven different aliphatic or aromatic nitriles. A subset of these organisms expressing broad substrate ranges was evaluated for their ability to hydrolyse β-substituted nitriles (3-amino-3-phenylpropionitrile and 3-hydroxy-4-phenoxybutyronitrile) and the active organisms were found to be Rhodococcus erythropolis from uncultivated soil and Rhodococcus rhodochrous from agricultural soils.
  
  
  CONCLUSIONS
  The capacity for hydrolysis of β-substituted nitriles appears to reside almost exclusively in Rhodococci. Land use has a much greater effect on the biocatalysis substrate profile than geographical location.
  
  
  CONCLUSIONS
  Enzymes are typically substrate specific in their catalytic reactions, and this means that a wide diversity of enzymes is required to provide a comprehensive biocatalysis toolbox. This paper shows that the microbial diversity of nitrile hydrolysis activity can be targeted according to land utilization. Nitrile biocatalysis is a green chemical method for the enzymatic production of amides and carboxylic acids that has industrial applications, such as in the synthesis of acrylamide and nicotinamide. The biocatalysts discovered in this study may be applied to the synthesis of peptidomimetics which are an important class of therapeutic compounds.
authors.affiliation: Department of Biotechnology and Food Technology, Tshwane University of Technology, Pretoria, South Africa.
authors.forename: O K L
authors.initials: OK
authors.lastname: Rapheeha
authors.affiliation: Department of Biotechnology and Food Technology, Tshwane University of Technology, Pretoria, South Africa.
authors.forename: M P
authors.initials: MP
authors.lastname: Roux-van der Merwe
authors.affiliation: Department of Biotechnology and Food Technology, Tshwane University of Technology, Pretoria, South Africa.
authors.forename: J
authors.initials: J
authors.lastname: Badenhorst
authors.affiliation: CSIR Biosciences, Pretoria, South Africa.|Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: V
authors.initials: V
authors.lastname: Chhiba
authors.affiliation: Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: M L
authors.initials: ML
authors.lastname: Bode
authors.affiliation: CSIR Biosciences, Pretoria, South Africa.
authors.forename: K
authors.initials: K
authors.lastname: Mathiba
authors.affiliation: Department of Biotechnology and Food Technology, Tshwane University of Technology, Pretoria, South Africa.|CSIR Biosciences, Pretoria, South Africa.|Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: D
authors.initials: D
authors.lastname: Brady
mesh_terms: D000577:Amides / Q000378:metabolism; D002264:Carboxylic Acids / Q000378:metabolism; D002384:Catalysis; D006868:Hydrolysis; D009570:Nitriles / Q000378:metabolism*; D012240:Rhodococcus / Q000302:isolation & purification / Q000378:metabolism*; D012988:Soil Microbiology; D013019:South Africa
chemical_list: D000577:Amides; D002264:Carboxylic Acids; D009570:Nitriles
keywords: Rhodococcus; biocatalysis; nitrile hydratase; nitriles; peptidomimetics