A newly isolated novel bacterium from sediments contaminated with dyestuff was identified as Pseudomonas aeruginosa strain BCH by 16S rRNA gene sequence analysis. The bacterium was extraordinarily active and operative over a wide rage of temperature (10-60 degrees C) and salinity (5-6%), for decolorization of Direct Orange 39 (Orange TGLL) at optimum pH 7. This strain was capable of decolorizing Direct Orange 39; 50 mg l(-1) within 45 +/- 5 min, with 93.06% decolorization, while maximally it could decolorize 1.5 g l(-1) of dye within 48 h with 60% decolorization. Analytical studies as, UV-Vis spectroscopy, FTIR, HPLC were employed to confirm the biodegradation of dye and formation of new metabolites. Induction in the activities of lignin peroxidases, DCIP reductase as well as tyrosinase was observed, indicating the significant role of these enzymes in biodegradation of Direct Orange 39. Toxicity studies with Phaseolus mungo and Triticum aestivum revealed the non-toxic nature of degraded metabolites.

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.

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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.