Tuning of fed-batch cultivation of Streptomyces clavuligerus for enhanced Clavulanic Acid production based on genome-scale dynamic modeling

Streptomyces clavuligerus (S. clavuligerus) is a filamentous Gram-positive bacterial producer of the β-lactamase inhibitor clavulanic acid (CA). Antibiotics biosynthesis and secretion in the Streptomyces genus are closely related with nutritional and environmental perturbations. In this study, the low productivity of CA in wild-type S. clavuligerus was analyzed by implementing a dynamic flux balance approach (dFBA) coupled to a validated genome-scale metabolic network of the organism. The dynamic analysis of fluxes evidenced the key role of the central metabolism (glycolysis, TCA and urea cycles) in regulating the carbon fluxes of the CA biosynthesis. CA production was favored by the fed-batch operation under high shear stress conditions that stimulates the growth rate and the carbon fluxes along the central metabolism. Dynamic experiments in silico allowed to identify potential scenarios of enhanced CA production (up to 2.5-fold higher) by maintaining the conversion rates within the central and secondary metabolism through fed-batch operation. The experimental validation of the most feasible production scenario as identified in silico showed 2.2-fold increase of CA production (equivalent to 0.382 mmol gDCW−1) by using the feeding condition as a mechanism to stimulate the carbon fluxes along the central metabolism and CA biosynthesis.