Genetically engineered Streptomyces clavuligerus strains with improved capabilities to produce clavulanic acid are provided. The strains are genetically engineered by disrupting newly identified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes. This results in an increased intracelluar pool of the clavulanic acid precursor D-glyceraldehyde-3-phosphate (D-G3P), and increased clavulanic acid production. Clavulanic acid production may be further increased by supplying arginine to the medium in which the S. clavuligerus is grown.