Modeling and optimising lactose fermentation using a fluorosensor

Lactose has been fermented in a Tokyo Rikakikai Fermentor using two percent seeding at various temperatures. The progress of the reaction was followed by measuring the fluorescent signal due to NADH with a Dr. Ingold (Switzerland) fluorosensor which has an excitation wave length of 360 nm and measurement wavelength of 450 nm. The optimum temperature for this fermentation reaction is 34 degree celsius. At this temperature while biomass growth rate and final biomass concentration are a maximum the time taken to reach the final biomass concentration and lag time are a minimum. The fluorescent voltage vs time data fitted a first order plus dead time model with an error of less than one percent. The present work is in good agreement with earlier work on glucose and lactose fermentation with one percent seeding. The increase in seeding from one to two percent has improved the optimum parameters studied. Further work on higher seeding concentration and higher order models is in progress.