Optimization of melanin production by Brevundimonas sp. SGJ using response surface methodology

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 fur- ther 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 R 2 value 0.9667. The optimization of process parameters using RSM resul- ted 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 incu- bation period with dry cell weight of 0.711 g l -1 . The