title: Aspergillus niger PA2: a novel strain for extracellular biotransformation of L-tyrosine into L-DOPA.
abstract: L-DOPA (3,4-dihydroxyphenyl-L-alanine), an amino acid derivative is the most widely used drug of choice for the treatment of Parkinson's disease and other neurologic injuries. The present study deals with the elevated biochemical transformation of L-tyrosine to L-DOPA by Aspergillus niger PA2, a potent tyrosinase producer, isolated from decomposed food wastes. This appears to be the first report on A. niger as a notable extracellular tyrosinase producer. The extracellular tyrosinase activity produced remarkably higher levels of L-DOPA, i.e. 2.44 mg mL(-1) when the media was supplemented with 5 mg mL(-1) L-tyrosine. The optimum pH for tyrosinase production was 6.0, with the maximal L-DOPA production at the same pH. The product thus produced was analyzed by thin-layer chromatography, UV spectroscopy, high-performance liquid chromatography and Fourier transform infrared spectroscopy, that had denoted this to be L-DOPA. Kinetic parameters viz. Y p/s, Q s and Q p had further indicated the notable levels of production. Thus, Aspergillus niger PA2 could be a promising resource and may be further exploited for large-scale production of L-DOPA.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
authors.forename: Pragati
authors.initials: P
authors.lastname: Agarwal
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.|Department of Microbiology, Central University of Rajasthan, Ajmer, 305817, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Pareek
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
authors.forename: Swati
authors.initials: S
authors.lastname: Dubey
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Singh
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India. rpsbsfbs@iitr.ac.in.
authors.forename: R P
authors.initials: RP
authors.lastname: Singh
mesh_terms: D001234:Aspergillus niger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001711:Biotransformation; D004295:Dihydroxyphenylalanine / Q000737:chemistry / Q000378:metabolism*; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010802:Phylogeny; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism*
chemical_list: D014443:Tyrosine; D004295:Dihydroxyphenylalanine
keywords: Aspergillus niger; Biotransformation; L-DOPA; Tyrosinase