Patent ID: 8895310

Claim:
A method for expressing nucleic acid sequences in prokaryotic host cells by high-density cell fermentation, comprising; a) introducing into a prokaryotic host cell at least one DNA construct which is capable of episomal replication in said prokaryotic host cell and comprises a nucleic acid sequence to be expressed under the transcriptional control of an L-rhamnose-inducible promoter, wherein said L-rhamnose-inducible promoter is heterologous with regard to said nucleic acid sequence, b) selecting prokaryotic host cells which comprise said DNA construct in episomal form, and c) inducing the expression of said nucleic acid sequence by addition of L-rhamnose to a high-density cell culture of said selected prokaryotic host cells, wherein the concentration of L-rhamnose in the medium is from 0.01 g/l to 0.5 g/l, wherein the prokaryotic host cell is at least deficient with regard to L-rhamnose isomerase.