A novel Bacillus subtilis expression vector based on bacteriophage φ105

Abstract

We have developed a novel expression vector based on the bacteriophage φ105, and employed it for the production of mutant β-lactamases in Bacillus subtilis. Expression of the β-lactamase-encoding gene was low when cloned into the prophage under the control of its own promoter. However, expression was considerably elevated when the gene was inserted into the phage genome in the same orientation as phage transcription. A defective φ105 vector was constructed with a deletion removing a region needed for cell lysis, and with a mutation in the immunity repressor, rendering it temperature sensitive. Production of β-lactamase could then be induced by a shift in temperature and without concomitant cell lysis, facilitating purification of the protein from the culture supernatant. This phage has considerable potential for development as a vector for controllable production of heterologous proteins in B. subtilis.