Response Surface Optimization for Decaffeination and Theophylline Production by Fusarium solani

Coffee processing industries generate caffeine-containing waste that needs to be
treated and decaffeinated before being disposed. Five fungal isolates obtained on caffeinecontaining
mineral media were tested for their ability to utilize caffeine at high concentrations.
An isolate identified as Fusarium solani could utilize caffeine as a sole source of carbon and
nitrogen up to 5 g/l and could degrade it to an extent of 30–53 % in 120 h. Sucrose that was
added as an auxiliary substrate (5 g/l) enhanced the biodecaffeination of caffeine to 88 % in
96 h. The addition of co- substrate (sucrose) not only resulted in higher biodecaffeination
efficiency, but also reduced the incubation period from the initial 120 to 96 h. Theophylline
and 3-methyl xanthine were obtained as the major metabolites of decaffeination at 96 and
120 h, respectively. Response surface methodology used to optimize the process parameters
for maximum biodecaffeination as well as theophylline production showed that a pH of 5.8,
temperature of 24 °C and inoculum size of 4.8 × 105 spores/ml have resulted in a complete
biodecaffeination of caffeine as well as the production of theophylline with a yield of 33%(w/w).
Results thus show that a viable and sustainable process can be developed for the
detoxification of caffeine along with the recovery of theophylline, a commercially
important chemical.