Investigate sensors for bioreactor control.

Scientists at Therasense Inc. (1360 South Loop Rd., Alameda, CA 94502) are developing in-situ, steam-sterilizable, amperometric sensors for controlling bioreactors in pharmaceutical, food, beverage and fermentation applications. The sensors detect glucose concentrations during fermentation. In-situ sensors for bioprocessing applications are not commonly available.

Glucose concentrations can change drastically within minutes in bioreactors. In-situ real-time monitoring of these levels will facilitate effective bioprocess control. Therasense has proven the technology works in a Phase I Small Business Technology Transfer program award from the U.S. National Science Foundation (NSF). The company is finishing up more advanced work in a Phase II award from NSF and will consider collaborating with industry to commercialize the technology. At the end of Phase II, prototype sensors for beta testing will be available to industry.

In Phase I, a prototype in-situ sensor was able to monitor reliably the glucose concentration in E. coli fermentations. Importantly, the sensor housing, consisting of a stainless steel holder and an autoclavable membrane, was capable of monitoring sterility for several days and was highly resistant to fouling.

In Phase II, the sensor chemistry is being made robust. The sensor's structure and components are being designed so that they can be manufactured at low cost. Its range of analyses is being expanded to include, in addition to glucose, lactate and glutamate. Moreover, the sensor is being tested, in addition to E. coli fermentations, in fermentations of yeast Saccharomyces cerevisiae and Streptomyces, a mycelial organism. Membranes and monolithic injection-molded insert structures will be designed for high reliability and manufacturability. Further information. Michael Tomasco; phone: [phone]; fax: [phone]; email: [e-mail].