Fungal biotransformation of synthetic levodopa to stable dopamine in l-ascorbate-mediated aerobic-thermophilic biochemical process
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In the present study, fungal biotransformation of synthetic levodopa to stable dopamine in an l-ascorbate-mediated thermophilic-aerobic biochemical reaction was investigated. A mutant strain of Aspergillus oryzae EMS-6 was used for the preparation of mycelial biomass. The mutant was previously developed through EMS-induced mutagenesis and repressed against l-cysteine HCl. Growth parameters such as rate of cultivation (48 h), initial pH (6) and incubation temperature (30 °C) supported 18.84 g/l biomass with 23 g/l glucose consumption. Thermophilic behaviour of culture was observed at 25–40 °C. Kinetic variables notably µ = 0.385 /h and Qs, exhibited consistent growth pattern. Biochemical reactions were performed aerobically using mycelial biomass as the source of enzyme ‘tyrosinase’ in a digital hotplate equipped with magnetic stirrers. The reaction conditions included 5 mg/ml biomass and 2.5 mg/ml levodopa as basal substrate in a thermophilic reaction of 25 min duration acidified with l-ascorbic acid. TLC and HPLC analysis of reaction mixture confirmed the presence of levodopa and dopamine using a CN-9dth (R) column. Activation enthalpy and entropy of dopa decarboxylase (DDC) and its thermal inactivation showed an improved biotransformation of levodopa to dopamine at the optimal temperature (30 °C) as compared to other temperatures being employed. Overall, 3.68 mg/ml dopamine (4.55 mg/ml proteins) synthesis from 2.38 mg/ml levodopa was accomplished. The enhancement in metabolic activity of the mutant strain is ~ 2.75-fold improved when compared to the unoptimized reaction conditions, which is highly significant (HS) indicating an eco-commercially viable (LSD ~ 0.412) bioprocess.
KeywordsAspergillus oryzae Levodopa Dopamine Dopa decarboxylase Biotransformation l-ascorbate
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Conflict of interest
The author declares that there is no conflict of interest.
- Arnow LE (1973) Colorimetric determination of the components of l-3,4-dihydroxy phenylalanine in tyrosine mixtures. J Biochem 88:531Google Scholar
- Haneda K, Watanabe S, Takeda P (1973) l-DOPA by microorganisms. J Ferment Technol 51:398–406Google Scholar
- Hodgetts RB, O’Keefe SL (2006) Dopa decarboxylase: a model gene-enzyme system for studying development, behaviour and systematics. Annu Rev Entomol 51:259–284. https://doi.org/10.1146/annurev.ento.51.110104.151143 CrossRefPubMedGoogle Scholar
- Pirt SJ (1975) Principles of cell cultivation. Blackwells Scientific Corporation, LondonGoogle Scholar
- Pontecarvo J, Roper JA, Hemmous LM, Buftan W (1969) Basic techniques of UV-irradiation and chemical mutation. Adv Genet 5:141–183Google Scholar
- Raju BG, Rao GH, Ayyanna C (1993) Bioconversion of tyrosine to melanin using mycelia of Aspergillus spp. CBS Publishers, VisakhapatnamGoogle Scholar
- Sirivelu MP, Mohankumar SMJ, Wagner JG, Harkema JR, Mohankumar PS (2006) Activation of the stress axis and neurochemical alterations in specific brain areas by concentrated ambient particle exposure with concomitant allergic airway disease. Environ Health Perspect 114:870–874CrossRefPubMedPubMedCentralGoogle Scholar
- Snedecor GW, Cochran WG (1980) Statistical methods, 7th edn. Ames, Iowa state University Press, Iowa.Google Scholar