MONITORING OF ENZYMATIC-HYDROLYSIS OF IVORY NUT MANNAN USING ONLINE MICRODIALYSIS SAMPLING AND ANION-EXCHANGE CHROMATOGRAPHY WITH INTEGRATED PULSED ELECTROCHEMICAL DETECTION

A new system for on-line monitoring of a small-scale bioprocess is des cribed, based on microdialysis sampling and anion-exchange chromatogra phy with integrated pulsed electrochemical detection. The microdialysi s probe equipped with a 16-mm polysulfone membrane was used as an in s itu Sampling unit, giving a clean dialysate with no further need for s ample clean-up. The system was used to continuously monitor the hydrol ysis of 0.25% ivory nut mannan using endo-1,4-beta-mannanase (mannan e ndo-1,4-beta-mannosidase; EC 3.2.1.78) from Aspergillus niger. The oli gosaccharides produced in the hydrolysis, 1,4-beta-D-mannobiose, manno triose, mannotetraose, and mannopentaose, were separated isocratically and detected electrochemically. On-line monitoring of the hydrolysis of mannan using the endo-mannanase from A. niger, in a 5-ml reaction v essel, was achieved using 50 mM NaOH as mobile phase for 32 h without sampling or detection problems.