(466c) Effect of Different Feeding Strategies of Glucose and Short-Chain Carboxylic Acids on the Production of Natamycin By Streptomyces Natalensis

Natamycin is an industrially important tetraene antibiotic produced in submerged culture by different strains of Streptomyces sp. Natamycin has a wide spectrum activity against molds and yeasts with low toxicity against mammalian cells. It is used in the treatment of bronchopulmonary aspergillosis, mycotic keratitis, yeast keratomycosis and candidiasis. Natamycin is used in many food industries for food preservation and has been granted the GRAS status (Generally Regarded As a Safe) by FDA. This present work was carried out to investigate the optimization of natamycin production through different feeding strategies of glucose as a limiting substrate as well as short-chain carboxylic acids (acetic, propionic and butyric) and their effect on cell growth and natamycin biosynthesis. The optimization was performed in shake-flask level as well as 2-L stirred-tank bioreactor. Cultivations have been evaluated under different feeding strategies of glucose as a limiting substrate, as well as different short-chain carboxylic acids (acetate,propionate, and butyrate) . The obtained results showed that the highest natamycin level was obtained at 20 g.L⁻¹ glucose. Moreover, increasing glucose concentration resulted in a significant decrease in natamycin level. In addition, natamycin decomposition was observed at lower glucose concentrations (10-20 g.L^-1) after glucose depletion. The addition of acetic and propionic acids at concentrations below 2 g.L⁻¹ at cultivation start showed stimulatory effects on natamycin production. Furthermore, the addition of acetic and propionic acids in a mixture (7:1) at a total concentration of 2 g.L^-1, increased antibiotic production significantly. Conclusively, the addition of short chain carboxylic acids increased antibiotic yield and decreased the production time.