Use of an ethanol sensor for feedback control of growth and expression of TBV25H in Saccharomyces cerevisiae

Abstract

A process for production of a malaria transmission blocking vaccine candidate under the control of the ADH2 promoter in Saccharomyces cerevisiae was developed. Monitoring and controlling the ethanol concentration during the process is essential for successful expression of the recombinant protein. A simple sensor accomplishing this task has been developed, the principle of its operation is the following: air-flow through silicone tubing submerged in the media picks up ethanol, which is detected by an alcohol sensor that relays a signal to a controller regulating the amount of ethanol added to the culture. The sensor was used successfully in high cell density cultures of various scales.

Fermentation strategies for recombinant protein expression in the methylotrophic yeastPichia pastoris

“…(4). When growth is methanol-limited and S is too low to be controlled well by the sensor, the programmed method works better than methanol control, but when running a MFP at high S, on-line methanol monitoring and control becomes necessary to keep a constant S. A Figaro model TGS822 SnO 2 organic vapor sensor (Figaro Engineering Inc., Osaka, Japan) is commonly used to equip a methanol/ethanol on-line sensing device [41,42,46,47]. Based on the gas-liquid phase equilibrium, there are two techniques for using the sensor to monitor the methanol in fermentation broth.…”

“…Based on the gas-liquid phase equilibrium, there are two techniques for using the sensor to monitor the methanol in fermentation broth. One method detects the methanol vapor in off-gas [42,46], while the other detects methanol vapor that permeates from the broth across a silicone tube [41,47]. A hollow silicone tube is submerged into the fermentor where methanol in the broth diffuses through the tubing, is picked up by a stream of air, and is carried to an external sensor.…”

Fed-batch cultivation of Saccharomyces cerevisiae on lignocellulosic hydrolyzate

“…One principle which has been used for aerobic fed-batch control of S. cerevisiae with high yield is that of maintaining a low and constant ethanol concentration in the broth (Axelsson et al 1988;Noronha et al 1999;Cannizzaro et al 2004). If the flow rate is lower than the maximum respiratory sugar uptake, ethanol will be consumed, signalling that the flow rate can be increased.…”

Control of yeast fed-batch process through regulation of extracellular ethanol concentration

“…Fortunately, due to modern developments in this field, a wide selection of methods are available [9,10], such as flow injection analysis [11], near infrared spectroscopy [12,13], mid-infrared spectroscopy [14][15][16], HPLC [6], inexpensive gas sensors [8], biosensors [17,7,18,19] and mass spectrometry [20].…”