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L-DOPA is an amino acid derivative and most potent drug used against Parkinson's disease, generally obtained from Mucuna pruriens seeds. In present communication, we have studied the in vitro production of L-DOPA from L-tyrosine by novel bacterium Bacillus sp. JPJ. This bacterium produced 99.4% of L-DOPA from L-tyrosine in buffer (pH 8) containing 1 mg ml(-1) cell mass incubated at 40°C for 60 min. The combination of CuSO(4) and L-ascorbic acid showed the inducing effect at concentrations of 0.06 and 0.04 mg ml(-1), respectively. The activated charcoal 2 mg ml(-1) was essential for maximum bioconversion of L-tyrosine to L-DOPA and the crude tyrosinase activity was 2.7 U mg(-1) of tyrosinase. Kinetic studies showed significant values of Y (p/s) (0.994), Q (s) (0.500) and q (s) (0.994) after optimization of the process. The production of L-DOPA was confirmed by analytical techniques such as HPTLC, HPLC and GC-MS. This is the first report on rapid and efficient production of L-DOPA from L-tyrosine by bacterial source which is more effective than the plant, fungal and yeast systems.

Melanins are predominantly indolic polymers which are extensively synthesized in animals, plants and microorganisms. It has wide applications in cosmetics, agriculture and medicine. In the present study, optimization of process parameters influencing melanin production was attempted using the response surface methodology (RSM) from Brevundimonas sp. SGJ. A Plackett–Burman design was used for screening of critical components, while further optimization was carried out using the Box–Behnken design. The optimum conditions observed were pH 5.31, tryptone 1.440 g l−1, l-tyrosine 1.872 g l−1 and CuSO4 0.0366 g l−1. Statistical analysis revealed that the model is significant with model F value 29.03 and R2 value 0.9667. The optimization of process parameters using RSM resulted in a 3.05-fold increase in the yield of melanin. The intermittent addition of l-tyrosine enhanced the melanin yield to 6.811 g l−1. The highest tyrosinase activity observed was 2,471 U mg−1 at the 18th hour of the incubation period with dry cell weight of 0.711 g l−1. The melanin production was confirmed by UV–Visible spectroscopy, FTIR and EPR analysis. Thus, Brevundimonas sp. SGJ has the potential to be a new source for the production of melanin.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-012-0082-4) contains supplementary material, which is available to authorized users.

ABSTRACT

Summaryl‐DOPA (3,4‐dihydroxyphenyl‐l‐alanine) is an extensively used drug for the treatment of Parkinson's disease. In the present study, optimization of nutritional parameters influencing l‐DOPA production was attempted using the response surface methodology (RSM) from Brevundimonas sp. SGJ. A Plackett–Burman design was used for screening of critical components, while further optimization was carried out using the Box–Behnken design. The optimized levels of factors predicted by the model were pH 5.02, 1.549 g l−1 tryptone, 4.207 g l−1 l‐tyrosine and 0.0369 g l−1 CuSO4, which resulted in highest l‐DOPA yield of 3.359 g l−1. The optimization of medium using RSM resulted in a 8.355‐fold increase in the yield of l‐DOPA. The anova showed a significant R2 value (0.9667), model F‐value (29.068) and probability (0.001), with insignificant lack of fit. The highest tyrosinase activity observed was 2471 U mg−1 at the 18th hour of the incubation period with dry cell weight of 0.711 g l−1. l‐DOPA production was confirmed by HPTLC, HPLC and GC‐MS analysis. Thus, Brevundimonas sp. SGJ has the potential to be a new source for the production of l‐DOPA.