Enhancement of a high efficient autoinducible expression system in Bacillus subtilis by promoter engineering

Abstract Quorum-sensing related promoter srfA (P srfA ) was used to construct autoinducible expression system for production of recombinant proteins in Bacillus subtilis . P srfA was prominent in the unique property of inducer-free activity that is closely correlated with cell density. Here, using green fluorescent protein (GFP) as the reporter protein, P srfA was optimized by shortening its sequences and changing the nucleotides at the conserved regions of −35 −15 and −10 regions, obtaining a library of P srfA derivatives varied in the strength of GFP production. Among all the promoter mutants, the strongest promoter P10 was selected and the strength in GFP expression was 150% higher than that of P srfA . Heterologous protein of aminopeptidase and nattokinase could be overexpressed by P10, the activities of which were 360% and 50% higher than that of P srfA , respectively. These results suggested that the enhanced promoter P10 could be used to develop autoinducible expression system for overexpression of heterologous proteins in B. subtilis .