Application of yeast imprinting in biotechnology and process control

Rapid advancements in biotechnology depend on the development of reliable sensing sytems adaptable to a variety of analytes. Molecularly imprinted polymers combined with mass-sensitive devices (10 MHz QCMs) provide a reliable and robust method to observe cell growth and allow cell specifications in real-time. Such biosensors selectively detect fermenting yeast in a complex matrix and 10(4) cells/microl in solution correspond to an adhesion of approximately 3 x 10(3) cells on the sensor coating. Over a period of up to 40 hours, the growth of the microorganism at 30 degrees C was observed in various nutrient solutions of glucose, peptone and ammonium sulfate, thereby rendering the determination of optimum growth conditions possible. While almost no change, i.e. no cell propagation, occurred in the absence of glucose, the frequency decreases to more than 700 Hz under rich conditions. Increasing the depth of the imprints to more than 1.5 microm the yeast cells are so strongly bound that they are fixed in the material. With such gravimetric sensors, for instance osmotic effects of cells can be followed by a frequency change of 3 kHz by altering the ion strength by 0.1 M.