The influence of carbon sources and morphology on nystatin production by Streptomyces noursei.

Carbon source nutrition and morphology were examined during cell growth and production of nystatin by Streptomyces noursei ATCC 11455. This strain was able to utilise glucose, fructose, glycerol and soluble starch for cell growth, but failed to grow on media supplemented with galactose, xylose, maltose, sucrose, lactose and raffinose. Utilisation of glucose had a negative influence on production of nystatin independent of the specific growth rate when phosphate and ammonium was in excess. Consumption of carbon sources was related to the specific growth rate. S. noursei ATCC 11455 formed mainly mycelial clumps during cultivation, while pellet growth dominated the culture of the morphologically altered high producing mutant S. noursei NG7.19. When the pellet size increased above a critical size, cell growth and nystatin production terminated. Fluorescent staining of hyphae revealed that this coincided with loss of activity inside the core of the pellets, probably due to diffusion limitation of oxygen or other nutrients.