title: Identification of nitrile hydratase-producing Rhodococcus ruber TH and characterization of an amiE-negative mutant.
abstract: Microbial transformation of acrylonitrile to acrylamide by nitrile hydratase is of great interest to green chemistry. During the transformation, acrylic acid is generally accumulated as a by-product through biocatalysis of amidase. A novel strain with high nitrile hydratase activity was isolated from soil and identified as Rhodococcus ruber TH by morphology and 16S rRNA gene analysis. An amidase-negative recombinant, R. ruber TH3 was constructed. Its nitrile hydratase activity was 25% higher than that of the wild type, reaching 490+/-29.2U/mg dry cell weight, while the amidase activity was 60% lower. After 6 h hydration of acrylonitrile using free cells as biocatalysts at 18 degrees C, acrylamide production by TH3 was 23% higher and the production of the by-product, acrylic acid, was 87% lower than that of the wild type. This result demonstrates that the strain TH3 could be valuable for industrial applications.
authors.affiliation: Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China. yuhm@tsinghua.edu.cn
authors.forename: Yuchao
authors.initials: Y
authors.lastname: Ma
authors.forename: Huimin
authors.initials: H
authors.lastname: Yu
authors.forename: Wenyu
authors.initials: W
authors.lastname: Pan
authors.forename: Changchun
authors.initials: C
authors.lastname: Liu
authors.forename: Shuliang
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhongyao
authors.initials: Z
authors.lastname: Shen
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D055786:Gene Knockout Techniques; D006836:Hydro-Lyases / Q000096:biosynthesis*; D009154:Mutation / Q000235:genetics; D012240:Rhodococcus / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D000581:Amidohydrolases; C019665:amidase; D006836:Hydro-Lyases; C048831:nitrile hydratase