CHARACTERIZATION AND APPLICATION OF AN ON-LINE FLOW-INJECTION ANALYSIS WALL-JET ELECTRODE SYSTEM FOR GLUCOSE MONITORING DURING FERMENTATION

An on-line system for glucose monitoring during fermentation was devel oped. The system employed flow-injection analysis coupled with a wall- jet electrode. Glucose was converted enzymatically in a tubular reacto r packed with controlled pore glass beads containing immobilized gluco se oxidase. The hydrogen peroxide produced was detected amperometrical ly. A filtration/sampling module operated by a peristaltic pump enable d sample withdrawal from the fermenter. The system was interfaced to a programmable language controller which was in turn linked to a microc omputer. The dual injection valve of the now system was operated in a novel configuration to achieve sample dilution, by dispersion, and sta ndardization simultaneously. The developed system was characterized fo r dilution factor, stability and linearity of response. After conditio ning of the reactor, sample peak heights were found to have a precisio n of 1.07% (R.S.D., 25 determinations) when the glucose concentration was 1.32 g l(-1). Under the conditions studied, linear response to glu cose concentration from 0.062 to 4.0 g l(-1) was obtained. Sample thro ughput was about 7 per hour. Interferences from the fermentation media were negligible after filtration through the sampling module and dilu tion. The on-line system was applied to glucose monitoring during E. c oli fermentation. Good results were obtained as shown by the high cell density (OD600m = 168 in 9 h fermentation), constant specific growth rate (mu = 0.66) and lower acetate accumulation (less than 2 g l(-1) w hen OD600m was over 50).