Efficient microbial conversion of L-tyrosine to L-DOPA by Brevundimonas sp. SGJ.

L-DOPA (3,4-dihydroxyphenyl-L-alanine), the most widely used drug for the treatment of Parkinson's disease, was produced in buffer using biomass of Brevundimonas sp. SGJ. The effects of enhancers, such as carrageenan, diatomaceous earth, and activated charcoal, on the L-DOPA production were evaluated to obtain the maximum yield. The optimal process conditions found were pH 8, 2 g l⁻¹ cell mass, 2 g l⁻¹ L-tyrosine, 0.04 g l⁻¹ CuSO₄, 0.02 g l⁻¹ L-ascorbic acid, 0.5 g l⁻¹ carrageenan, and 40 °C temperature. In addition, repeated use of cells resulted in the highest yield of 3.81 g l⁻¹ (95.2%) of L-DOPA with utilization of 4 g l⁻¹ L-tyrosine, and the highest tyrosinase activity (9,201 U mg⁻¹) was observed at 18 h of incubation. Furthermore, the produced L-DOPA was confirmed by high-performance thin-layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectroscopy. Kinetic studies showed significant values of Y (p/s), Q (s), and q (s) after optimization of the process. Thus, Brevundimonas sp. SGJ could be an eventual new source for large-scale production of L-DOPA.