title: Biotransformation of L-tyrosine to Dopamine by a Calcium Alginate Immobilized Mutant Strain of Aspergillus oryzae.
abstract: The present research work is concerned with the biotransformation of L-tyrosine to dopamine (DA) by calcium alginate entrapped conidiospores of a mutant strain of Aspergillus oryzae. Different strains of A. oryzae were isolated from soil. Out of 13 isolated strains, isolate-2 (I-2) was found to be a better DA producer. The wild-type I-2 was chemically improved by treating it with different concentrations of ethyl methyl sulfonate (EMS). Among seven mutant variants, EMS-6 exhibiting maximal DA activity of 43 μg/ml was selected. The strain was further exposed with L-cysteine HCl to make it resistant against diversion and environmental stress. The conidiospores of selected mutant variant A. oryzae EMS-6 strain were entrapped in calcium alginate beads. Different parameters for immobilization were investigated. The activity was further improved from 44 to 62 μg/ml under optimized conditions (1.5 % sodium alginate, 2 ml inoculum, and 2 mm bead size). The best resistant mutant variable exhibited over threefold increase in DA activity (62 μg/ml) than did wild-type I-2 (21 μg/ml) in the reaction mixture. From the results presented in the study, it was observed that high titers of DA activity in vitro could effectively be achieved by the EMS-induced mutagenesis of filamentous fungus culture used.
authors.affiliation: Institute of Industrial Biotechnology (IIB), GC University, Lahore, Pakistan. alisbiotech@yahoo.com.
authors.forename: Sikander
authors.initials: S
authors.lastname: Ali
authors.affiliation: Institute of Industrial Biotechnology (IIB), GC University, Lahore, Pakistan.
authors.forename: Wajeeha
authors.initials: W
authors.lastname: Nawaz
mesh_terms: D000464:Alginates / Q000494:pharmacology*; D001236:Aspergillus oryzae / Q000187:drug effects / Q000378:metabolism*; D001711:Biotransformation / Q000187:drug effects; D018914:Cells, Immobilized / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D020723:Glucuronic Acid / Q000494:pharmacology; D006603:Hexuronic Acids / Q000494:pharmacology; D016296:Mutagenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D025282:Mycelium / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D014443:Tyrosine; D020723:Glucuronic Acid; D004298:Dopamine
keywords: A. oryzae; Biotransformation; Calcium alginate; Dopamine; EMS