title: Development of a highly efficient indigo dyeing method using indican with an immobilized beta-glucosidase from Aspergillus niger.
abstract: A highly efficient method for dyeing textiles with indigo is described. In this method, the substrate, indican is first hydrolyzed at an acidic pH of 3 using an immobilized beta-glucosidase to produce indoxyl, under which conditions indigo formation is substantially repressed. The textile sample is then dipped in the prepared indoxyl solution and the textile is finally exposed to ammonia vapor for a short time, resulting in rapid indigo dyeing. As an enzyme, we selected a beta-glucosidase from Aspergillus niger, which shows a high hydrolytic activity towards indican and was thermally stable at temperatures up to 50-60 degrees C, in an acidic pH region. The A. niger beta-glucosidase, when immobilized on Chitopearl BCW-3001 by treatment with glutaraldehyde, showed an optimum reaction pH similar to that of the free enzyme with a slightly higher thermal stability. The kinetics for the hydrolysis of indican at pH 3, using the purified free and immobilized enzymes was found to follow Michaelis-Menten type kinetics with weak competitive inhibition by glucose. Using the immobilized enzyme, we successfully carried out repeated-batch and continuous hydrolyses of indican at pH 3 when nitrogen gas was continuously supplied to the substrate solution. Various types of model textiles were dyed using the proposed method although the color yield varied, depending on the type of textile used.
authors.affiliation: Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Song
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imanaka
authors.forename: Koreyoshi
authors.initials: K
authors.lastname: Imamura
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kajitani
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakanishi
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D004396:Coloring Agents / Q000138:chemical synthesis*; D004800:Enzymes, Immobilized / Q000737:chemistry; D007200:Indican / Q000737:chemistry*; D007203:Indigo Carmine; D007211:Indoles / Q000138:chemical synthesis*; D049231:Saposins / Q000737:chemistry*; D013784:Textiles
chemical_list: D004396:Coloring Agents; D004800:Enzymes, Immobilized; D007211:Indoles; D049231:Saposins; D007203:Indigo Carmine; D007200:Indican