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From 2011.igem.org

Expression of S-layer protein under control of T7 promoter in a bioreactor

[Image:IGEM-Bielefeld2011-Bioreaktor.JPG|400px|thumb|center|Inocculating a [http://www.bioengineering-inc.com/standard-reactors.php?id=2.1 Bioengineering NLF22 7 L] with Bioengineering DCU.]

The expression of S-layer proteins is stressful for Escherichia coli. So using E. coli [http://www.promega.com/products/cloning-and-dna-markers/cloning-tools-and-competent-cells/bacterial-strains-and-competent-cells/single-step-_krx_-competent-cells/ KRX] to express genes under the control of a T7 promoter is an easy way to overexpress your proteins and seperate growth and production phase. This strain carries a T7 polymerase gene under the control of a rhamnose promoter in its genome and it is also optimized for cloning so you do not have to transform your plasmids after assembly in e.g. TOP10, isolate them and bring them in an expression strain like BL21(DE3) - you can go with a single transformation step from assembly to production.

The advantage of a bioreactor over shaking flasks is the possibility to control cultivation parameters like temperature, pH or dissolved oxygen (DO).