title: Microbiological transformation of L-tyrosine to 3,4-dihydroxyphenyl L-alanine (L-dopa) by a mutant strain of Aspergillus oryzae UV-7.
abstract: The present study deals with the microbiological transformation of L-tyrosine to 3,4-dihydroxyphenyl L-alanine by a mutant strain of Aspergillus oryzae UV-7. Sixteen different mutant strains of Aspergillus oryzae (GCB-6) were isolated through UV-irradiation. These mutant strains were screened for the production of mold mycelia by submerged fermentation in 250-ml Erlenmeyer flasks. Of all the mutant strains examined, UV-7 gave maximum production of L-dopa (1.28 mg/ml). The reaction was carried out using mold mycelium as a source of enzyme tyrosinase in shake flasks. The maximum production of L-dopa was obtained when glucose (25 mg/ml) was used as the carbon source and NH(4)Cl (3 mg/ml) was used as the nitrogen source. The optimum pH for mycelium development was 5.0; L-dopa production was maximum at pH 3.5 of the reaction mixture. The reaction by mold mycelium (75 mg/ml) was carried out under acidic conditions. Optimum temp, time, and L-tyrosine concentration were 55 degrees C, 60 min, and 3.0 mg/ml, respectively.
authors.affiliation: Biotechnology Research Laboratories, Department of Botany, Government College, Lahore, Pakistan.
authors.lastname: Ikram-Ul-Haq
authors.forename: Sikander
authors.initials: S
authors.lastname: Ali
mesh_terms: D000409:Alanine; D001236:Aspergillus oryzae / Q000201:enzymology / Q000378:metabolism*; D001711:Biotransformation; D005285:Fermentation; D007980:Levodopa / Q000378:metabolism*; D009154:Mutation; D013696:Temperature; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D014443:Tyrosine; D007980:Levodopa; D000409:Alanine