| EJB Electronic Journal of Biotechnology ISSN:
0717-3458 | Vol. 5 No. 2, Issue of August 15, 2002 |
| © 2002 by Universidad Católica de Valparaíso -- Chile
| Received December 21, 2001 / Accepted June 4, 2002 | Novel
technique for microbial production of 3,4-Dihydroxy Phenyl L-alanine by a mutant
strain of Aspergillus oryzae Sikander
Ali*
Biotechnology Research Laboratories
Department of Botany
Faculty of Sciences
Government
College
Lahore, Pakistan
Tel: 92 42 9211634
Fax: 92 42 7243198
E-mail: alisbiotech@yahoo.com Ikram-ul-Haq
Biotechnology Research Laboratories
Department of Botany
Faculty
of Sciences
Government College
Lahore,
Pakistan
Tel: 92 42 9211634
Fax:
92 42 7243198
E-mail: ikrhaq@yahoo.com Qadeer,
M.A.
Centre of Excellence in Molecular
Biology
Thokar Niaz Baig
C/B
Road, Lahore, Pakistan
Tel: 92 42 7588977
Fax: 92 42 723198
E-mail:
qadeerma@yahoo.com
* Corresponding author
Financial support:
Principal, Government College Lahore, Pakistan.
Keywords:
amino acid, Aspergillus oryzae, fermentation, L-DOPA, L-tyrosine, Parkinson's
disease.
| Abbreviations: | Substrate
consumption parameters:
µ (h-1)
= specific growth rate
Yx/s
= g cells/g substrate utilized
Qs
= g substrate consumed/l/h
qs
= g substrate consumed/g cells/h
Qx
= g cells formed/l/h
Production formation
rates:
Qp = g citric acid
produced/litre/h
Yp/s = g citric
acid produced/g substrate consumed
Yp/x
= g citric acid produced/g cells formed
qp
= g citric acid produced/g cells/h. |
L-DOPA is
a useful drug for Parkinson's disease. This investigation deals with
the biosynthesis of L-DOPA by parental (GCB-6) and mutant (UV-7) strains
of Aspergillus oryzae. There was a marked difference between
the mycelial morphology and pellet type of the parental and UV-irradiated
mutant cultures. The mutant strain of Aspergillus oryzae UV-6
showed pellet-like mycelial morphology and improved tyrosinase activity.
Mould mycelium was used for biochemical conversion of L-tyrosine to
L-DOPA since tyrosinase is an intracellular enzyme. The mutant was
found to give 3.72 folds higher production of L-DOPA than the parental
strain. The comparison of kinetic parameters was also done which showed
greater ability of the mutant to yield L-DOPA (i.e. Yp/x
32.73 mg/mg with parent and 95.71 mg/mg with mutant). When cultures
grown for various incubation periods, were monitored for Qp,
Qs and qp, there was significant enhancement
(p<0.0025-0.005) in these variables by the mutant strain of Aspergillus
oryzae UV-7 over GCB-6 on all the rates.
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