title: Remaining acetamide in acetonitrile degradation using nitrile hydratase- and amidase-producing microorganisms.
abstract: The tandem conversion process involving nitrile hydratase- and amidase-producing microorganisms has potential for use in the treatment of acetonitrile-containing wastes. In that process, the acetamide hydrolysis step catalyzed by amidase is very slow compared with the acetonitrile hydration step catalyzed by nitrile hydratase, and a small amount of acetamide remains in the resulting solution. This study aimed to improve the efficiency of the acetamide hydrolysis step. An amidase-producing microorganism, Rhodococcus sp. S13-4, was newly obtained, whose use enabled rapid acetamide degradation. Though residual acetamide was still detected, it was successfully reduced by the addition of cation/anion mixed ion exchange resin or calcium hydroxide after the acetamide hydrolysis reaction using Rhodococcus sp. S13-4 cells. This result implies that acetamide hydrolysis and acetamide formation are in equilibrium. The incubation of Rhodococcus sp. S13-4 cells with high concentrations of ammonium acetate produced acetamide. The purified amidase from Rhodococcus sp. S13-4 revealed the acetamide formation activity (specific activity of 30.6 U/mg protein). This suggests that the amidase-catalyzed amide formation may cause the remaining of acetamide in the acetonitrile conversion process.
authors.affiliation: Gifu Prefectural Research Institute for Bioengineering, Kamihachiya, Minokamo, Gifu, Japan. kouyama@bio.rd.pref.gifu.jp
authors.forename: Erina
authors.initials: E
authors.lastname: Kohyama
authors.forename: Mizuho
authors.initials: M
authors.lastname: Dohi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yoshimura
authors.forename: Toyokazu
authors.initials: T
authors.lastname: Yoshida
authors.forename: Toru
authors.initials: T
authors.lastname: Nagasawa
mesh_terms: D000081:Acetamides / Q000378:metabolism*; D000097:Acetonitriles / Q000378:metabolism*; D000327:Adsorption; D000619:Aminohydrolases / Q000096:biosynthesis* / Q000302:isolation & purification; D002126:Calcium Hydroxide / Q000378:metabolism; D006836:Hydro-Lyases / Q000096:biosynthesis*; D007475:Ion Exchange Resins; D012240:Rhodococcus / Q000378:metabolism*
chemical_list: D000081:Acetamides; D000097:Acetonitriles; D007475:Ion Exchange Resins; C030686:acetamide; D000619:Aminohydrolases; C021867:nitrilase; D006836:Hydro-Lyases; C048831:nitrile hydratase; D002126:Calcium Hydroxide; C032159:acetonitrile