Production of ramoplanin antibiotic by submerged fermentation

Ramoplanin is a cell wall active lipoglycodepsipeptide antibiotic with high bactericidal activity against many clinically important multi-drug resistant bacteria. It has been fast tracked by US Food and Drug Administration, and is expected to be marketed in the coming years. However, its expensive cost due to the low production yield is the main obstacle for this antibiotic. Therefore optimization of fermentation conditions is required for high productivity. For this purpose, in this thesis, various industrial by-product nitrogen sources including soybean meal, meat-bone meal, poultry meal and fish meal, and different concentrations of trace metals including iron, potassium, magnesium, manganese and zinc were investigated for their influence on ramoplanin A2 production with respect to the incubation period. Ramoplanin A2 levels were determined by HPLC. The highest ramoplanin A2 level in nitrogen source containing media was determined as 406.805 mg/L in fish meal medium on seventh day, but the highest total ramoplanin A2 production was determined in poultry meal medium which is also lower priced. The highest ramoplanin A2 level in metal containing media was determined as 647.415 mg/L in 75 ppm zinc ion containing medium on seventh day. In addition, important parameters influencing antibiotic biosynthesis were also investigated. Total protein levels, total reducing sugar levels, protease, amylase and lipase activities were determined spectrofotometrically, whereas intracellular free amino acid levels were determined by HPLC. According to the results, it can be concluded that ramoplanin A2 production was generally stimulated with the increasing pH levels, limitation of carbon sources, and bioavailability of ramoplanin A2 precursors such as L-Leu, L-Thr, Gly L-Phe, D-Ser and D-Orn amino acids.