Biotechnology and Bioengineering, Vol.109, No.9, 2262-2270, 2012
Self-cycling operation increases productivity of recombinant protein in Escherichia coli
Self-cycling fermentation (SCF), a cyclical, semi-continuous process that induces cell synchrony, was incorporated into a recombinant protein production scheme. Escherichia coli CY15050, a lac- mutant lysogenized with temperature-sensitive phage lambda modified to over-express beta-galactosidase, was used as a model system. The production scheme was divided into two de-coupled stages. The host cells were cultured under SCF operation in the first stage before being brought to a second stage where protein production was induced. In the first stage, the host strain demonstrated a stable cycling pattern immediately following the first cycle. This reproducible pattern was maintained over the course of the experiments and a significant degree of cell synchrony was obtained. By growing cells using SCF, productivity increased 50% and production time decreased by 40% compared to a batch culture under similar conditions. In addition, synchronized cultures induced from the end of a SCF cycle displayed shorter lysis times and a more complete culture-wide lysis than unsynchronized cultures. Finally, protein synthesis was influenced by the time at which the lytic phase was induced in the cell life cycle. For example, induction of a synchronized culture immediately prior to cell division resulted in the maximum protein productivity, suggesting protein production can be optimized with respect to the cell life cycle using SCF. Biotechnol. Bioeng. 2012;109: 22622270. (c) 2012 Wiley Periodicals, Inc.