Biosynthesis of the Pyrroindomycins by Streptomyces rugosporus LL-42D005; Characterization of Nutrient Requirements

Streptomyces rugosporus LL-42D005 was shown to produce the novel pyrroindomycin antibiotics. Production of pyrroindomycin (α) and chloro-pyrroindomycin (β) was characterized in a semi-defined fermentation medium containing glucose, casein, phosphate, vitamins and minerals. Accumulation of pyrroindomycin β increased with increasing concentrations of glucose, reaching maximum titers at approximately 5g/L glucose. Glucose concentrations greater than 7.5g/L decreased pyrroindomycin β yields. Inhibition of pyrroindomycin accumulation at higher glucose concentrations could be reversed by increasing the casein concentration. Ammonium chloride, arginine or glutamine could replace casein as the sole nitrogen source for growth and pyrroindomycin production. Glucose, fructose or mannitol were utilized as the sole carbon source, while sucrose, maltose, glycerol, corn oil and starch were poorly metabolized. Incubation of this isolate in a vitamin-deficient medium resulted in a delay in growth and pyrroindomycin production; this delay was eliminated by the addition of biotin. Addition of L-tryptophan to the medium resulted in the production of pyrroindomycin α as the major species.