Development of an extremely flexible automatic analyzer with integrated biosensors for on-line control of fermentation processes

The development of a highly flexible sequential-injection system for the on-line control of fermentation processes is described. The developed system shows a significantly improved flexibility and adaptability to the needs of a particular fermentation process to be monitored as compared with conventional flow-injection systems. The number of necessary hardware components has also been drastically decreased, and the minimal injection volume decreased to 3–5 μl allowing improved dilution of an injected sample plug and improved mixing of coinjected reagents. A dilution factor can be adjusted to between 1 and 100 due to controlled dispersion of the injected sample plug within the tube system by choosing an appropriate injection volume. Due to the symmetrical design of the injection manifold and the versatile control software, complex injection profiles can be obtained that are necessary to coinject a sample together with a reagent or a sample together with one or two standard solutions for immediate recalibration. The system is fully automated, and the specially developed software package comprises automatic calibration and recalibration with up to 5 standard solutions, real-time calculation of the actual concentration values based on the most recent calibration data, documentation of the fermentation course, and injection of samples from up to 4 sampling sites with variable time basis.