title: Cr(VI) reduction by gluconolactone and hydrogen peroxide, the reaction products of fungal glucose oxidase: Cooperative interaction with organic acids in the biotransformation of Cr(VI).
abstract: The Cr(VI) reducing capability of growing cells of the environmental A. tubingensis Ed8 strain is remarkably efficient compared to reference strains A. niger FGSC322 and A. tubingensis NRRL593. Extracellular glucose oxidase (GOX) activity levels were clearly higher in colonies developed in solid medium and in concentrated extracts of the spent medium of liquid cultures of the Ed8 strain in comparison with the reference strains. In addition, concentrated extracts of the spent medium of A. tubingensis Ed8, but not those of the reference strains, exhibited the ability to reduce Cr(VI). In line with this observation, it was found that A. niger purified GOX is capable of mediating the conversion of Cr(VI) to Cr(III) in a reaction dependent on the presence of glucose that is stimulated by organic acids. Furthermore, it was found that a decrease in Cr(VI) may occur in the absence of the GOX enzyme, as long as the reaction products gluconolactone and hydrogen peroxide are present; this conversion of Cr(VI) is stimulated by organic acids in a reaction that generates hydroxyl radicals, which may involve the formation of an intermediate peroxichromate(V) complex. These findings indicated that fungal glucose oxidase acts an indirect chromate reductase through the formation of Cr(VI) reducing molecules, which interact cooperatively with other fungal metabolites in the biotransformation of Cr(VI).
authors.affiliation: Departamento de Biología, DCNyE, Universidad de Guanajuato, Campus Guanajuato, Noria Alta s/n, C.P. 36000, Guanajuato, Gto, Mexico.
authors.forename: Pamela
authors.initials: P
authors.lastname: Romo-Rodríguez
authors.affiliation: Departamento de Química, DCNyE, Universidad de Guanajuato, Campus Guanajuato, Noria Alta s/n, C.P. 36000, Guanajuato, Gto, Mexico.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Acevedo-Aguilar
authors.affiliation: Departamento de Biología, DCNyE, Universidad de Guanajuato, Campus Guanajuato, Noria Alta s/n, C.P. 36000, Guanajuato, Gto, Mexico.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Lopez-Torres
authors.affiliation: Departamento de Química, DCNyE, Universidad de Guanajuato, Campus Guanajuato, Noria Alta s/n, C.P. 36000, Guanajuato, Gto, Mexico.
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Wrobel
authors.affiliation: Departamento de Química, DCNyE, Universidad de Guanajuato, Campus Guanajuato, Noria Alta s/n, C.P. 36000, Guanajuato, Gto, Mexico.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Wrobel
authors.affiliation: Departamento de Biología, DCNyE, Universidad de Guanajuato, Campus Guanajuato, Noria Alta s/n, C.P. 36000, Guanajuato, Gto, Mexico. Electronic address: xilefgu@gmail.com.
authors.forename: J Félix
authors.initials: JF
authors.lastname: Gutiérrez-Corona
mesh_terms: D000143:Acids / Q000737:chemistry; D002857:Chromium / Q000737:chemistry*; D005942:Gluconates / Q000737:chemistry*; D005949:Glucose Oxidase / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D010084:Oxidation-Reduction; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D000143:Acids; D005942:Gluconates; D007783:Lactones; D009930:Organic Chemicals; D012989:Soil Pollutants; D002857:Chromium; C074702:chromium hexavalent ion; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; C010730:beta-glucono-1,5-lactone
keywords: Aspergillus sp.; Cr(VI) reduction; Gluconolactone–hydrogen peroxide; Glucose oxidase; Hydroxyl radicals; Organic acids