SBIR-STTR Award

This research is to develop the first in situ glucose and lactate sensors for bioreactor process control. These sensors will be designed to meet reasonable specifications for operational lifetime, resistance to fouling, and maintenance of bioreactor sterility. Multiple layeps of redox enzymes will be electrically connected to electrodes through electron-conducting hydrogels that are permeable to the substrates and the products of the enzymatic reaction. This process of enzyme "wiring" is the basis of the sensors, and allows them to control cell growth in bioreactors by monitoring substrates, products, toxins, etc. The successful completion of this research will improve the efficiency, reduce wastes, and lower manufacturing costs in bioreactors. These sensors will also simplify the monitoring process, add to understanding of control parameters, and begin the expansion of this technology to other analytes.

This Small Business Technology Transfer Phase II project will develop in situ, steam sterilizable, amperometric sensors for bioreactor control in the pharmaceutical, food/beverage and fermentation industries. At this time, in situ sensors for bioprocessing applications are not commonly available. Glucose concentrations can change drastically within minutes in bioreactors. In situ real time monitoring will provide the missing tool for effective bioprocess control. In Phase I a prototype in situ sensor was shown to monitor reliably the glucose concentration in E. coli fermentations. Importanty, the sensor housing, consisting of a stainless steel holder and an autoclavable membrane, was demonstrated to be capable of monitoring sterility for severa1 days and was highly resistant to fouling. In Phase II, the sensor chemistry will be made robust, its structure and components manufacturable at low cost, its range of analyses expanded to include, in addition to glucose, lactate and glutamate. Moreover the sensor will be tested, in addition to E. coli fermentations, in fermentation of yeast Saccharomyces cerevisiae, and Streptomyces, a mycelial organism. Membranes and monolithic, injection molded insert structure will be designed for high reliability and manufacturability. At the end of Phase II, prototype sensors for beta testing will be available for testing by the biotechnology industry.