Inactivation of the ybdD Gene in Lactococcus lactis Increases the Amounts of Exported Proteins

Random insertional mutagenesis performed on a Lactococcus lactis reporter strain led us to identify L. lactis ybdD as a proteinoverproducing mutant. In different expression contexts, the ybdD mutant shows increased levels of exported proteins and therefore constitutes a new and attractive heterologous protein production host. This study also highlights the importance of unknownregulatory processes that play a role during protein secretion.