Kinetics of cell growth and caffeine utilization by Pseudomonas sp. GSC 1182

Abstract

Caffeine in coffee pulp prevents the utilization of nutrition rich coffee pulp effectively. Microbial methods of caffeine degradation can help in detoxifying the pulp and it prove as a better alternative to the conventional methods of environmental unfriendly solvent extraction process of decaffeination. Previously Pseudomonas sp. GSC 1182 was isolated from the soil samples of coffee cultivation area to degrade caffeine. In this report, the cell growth kinetics of Pseudomonas sp. GSC 1182 at various concentration of caffeine ranging from 0.05 to 20 g/l was studied. The kinetic data showed substrate inhibition kinetics and maximum growth rate was obtained when the isolate was grown in medium containing 2.5 g/l of initial concentration of caffeine. The results also showed that the isolate was able to grow at high concentrations of caffeine (10 g/l). Different substrate inhibition models were fitted to the kinetic data and found the Luong model was best. The model predicted kinetic parameters were in agreement with the experimental findings. The kinetic parameters were: S m = 20.2 g/l; K S = 0.59 g/l; μ m = 0.24 h −1 and n = 2. This is the first detailed report on the cell growth kinetics of microorganism using caffeine as the substrate.