Superporous agarose monoliths as mini-reactors in flow injection systems -: On-line monitoring of metabolites and intracellular enzymes in microbial cultivation processes

A new type of agarose material, superporous agarose, was used as a support material in an analytical system designed for monitoring of bioprocesses with respect to metabolites and intracellular enzymes. The superporous agarose was used in the form of miniaturised gel plug columns (15x5.0 mM I.D. monolithic gel bed). The gel plugs were designed to have one set of very large pores (about 50 mum in diameter) through which cells, cell debris and other particulate contaminants from the bioreactor could easily pass. The material also had normal diffusion pores (300 Angstrom) characteristic of all agarose materials, providing ample surface for covalent attachment of antibodies and enzymes used in the analytical sequence. The superporous agarose gel plug columns were characterised with respect to flow properties and handling of heavy cell loads as well as dispersion of injected samples (a Bodenstein number of about 40 was observed with acetone tracer at a flow rate of 1 ml min(-1)). To evaluate the practical performance of the superporous gel plug columns, two applications were studied: (1) on-line determination of glucose in cultivation broth (gel plug with immobilized glucose oxidase) and (2) immunochemical quantification of intracellular beta -galactosidase in E. coli (gel plug with lysozyme to achieve cell lysis and gel plug with antibodies against beta -galactosidase).