Summary Lysine metabolism plays an important role in the formation of the insecticidal crystal proteins of Bacillus thuringiensis (Bt). The genes lam , gabD and sucA encode three key enzymes of the lysine metabolic pathway in Bt4.0718. The lam gene mainly affects the cell growth at stable period, negligibly affected sporulation and insecticidal crystal protein (ICP) production. While, the deletion mutant strains of the gabD an...