Vancomycin biosynthetic capacity was stimulated in oxygen-limited bioreactor culture (6.4% DOT) of Amycolatopsis orientalis, coinciding with a down-regulation of the culture growth and protein synthesis rates. However no Vancomycin was detected. ATP production was similar in oxygen-limited and oxygen-sufficient cultures (400-150 mu mole(ATP). g(biomass)(-1)). Our findings suggest a critical requirement for oxygen flux through the Vancomycin biosynthetic pathway, which is only met under nutrient-limited conditions in which oxygen is in excess.