Bacterial hypersecretion using mutant repressor sequence

An improved bacterial host cell useful for the inducible production and secretion in high yields of a heterologous protein is provided which contains a gene encoding the heterologous protein operatively linked to a secretory leader-encoding sequence and to an expression control sequence which contains a promoter region; and a second DNA sequence encoding a repressor capable of binding to said promoter region. The cell contains at least a mutation in the repressor binding region of the promoter or a mutation in the promoter binding region of the repressor-encoding sequence; or mutations in both regions. These mutation(s) lower the frequency of transcriptional induction by the promoter from the observed with the wild-type promoter and/or repressor-encoding sequence, resulting in higher yields of secreted heterologous protein.