Improved Natamycin Production in Streptomyces gilvosporeus Through Mutagenesis and Enhanced Nitrogen Metabolism

Natamycin is a polyene macrocyclic antibiotic extensively used in food, medical, and agricultural industries. However, its high production cost and low synthetic efficiency fail to meet the growing market demand. Therefore, enhancing the production of natamycin-producing strains is crucial for achieving its industrial-scale production. This study systematically evaluated 16 mutagenesis methods and identified atmospheric and room temperature plasma mutagenesis combined with 2-deoxyglucose tolerance screening as the optimal strategy for enhancing natamycin production. A high-yield mutant strain, AG-2, was obtained, achieving an 80% increase in natamycin production (1.53 g/L) compared to the original strain. Metabolic analysis revealed that glycolysis and the pentose phosphate pathway were enhanced in AG-2, while the tricarboxylic acid cycle was weakened, significantly increasing the supply of precursors such as acetyl-CoA, methylmalonyl-CoA, and the reducing power of NADPH. Additionally, overexpression of the nitrogen metabolism regulatory gene <i>glnR</i> promoted the supply of glutamate and glutamine, further increasing natamycin production in AG-2 to 1.85 g/L. In a 5 L fermenter, the engineered strain AG-<i>glnR</i> achieved a final natamycin production of 11.50 g/L, 1.67 times higher than the original strain. This study is the first to combine mutagenesis with nitrogen metabolism regulation, effectively enhancing natamycin production and providing a novel approach for the efficient synthesis of other polyene antibiotics.