At-line determination of glucose, ammonium and acetate in high cell density cultivations of Escherichia coli

A sophisticated measurement system for at-line determination of the main C-source glucose, the by-product acetate, and the N-source ammonium for high cell density cultivations (HCDC) of Escherichia coli K12 TG1 is presented. One flow diffusion technique (FDA) system is used for glucose measurement in the range of 0.5 up to 40 gL(-1) in the cultivation broth. Another FDA system detects the amount of the undesired by-product acetate. The ammonium concentration in the range of 0.2 to 2.5 gL(-1) is determined on-line by a flow injection analysis (FIA) system. For verification purposes, an HPLC system which is also connected to the bioreactor for at-line measurements is utilized. Several HCDC with cell densities of more than 100 gL(-1) have been carried out. The courses of growth-determining substrates have been detected at-line. All used systems have shown an excellent compliance with off-line measurements.