Enhanced biodegradation of caffeine by Pseudomonas sp using response surface methodology

Pseudomonas sp. NOM 5235 capable of degrading high concentrations of caffeine (>5 g/l) has been previously isolated from the soil of coffee plantation area. The critical medium components viz., KH2PO4, Na2HPO4, caffeine and Fe2+ affecting the rate of caffeine degradation were determined by Plackett-Burman design. These critical parameters were further optimized using response surface methodology. The optimum concentrations of KH2PO4, Na2HPO4, caffeine and Fe2+ were found to be 3.4 g/l, 0.352 g/l, 6.4 g/l and 0.075% (w/v), respectively. Under optimal conditions the caffeine degradation rate was increased to 0.18 g/(1 h) from 0.1 g/(1 h). Although the approach used for optimization is conventional, the increase in the rate of degradation of caffeine is significant. This is the first report on a strain capable of growing at higher concentrations of caffeine (>5 g/l) at maximum rate of degradation (0.18 g/(1h)). (C) 2007 Elsevier B.V. All rights reserved.