Respiratory chain of Streptomyces.

There is currently a great deal of interest in the streptomyces as producers of antibiotics, but relatively little is known about the mechanisms of intracellular energy supply in this group of organisms. They are aerobes, and carbohydrates serve as an energy source. There is good evidence that the pathways of carbohydrate metabolism in the streptomyces include the glycolysis sequence (Cochrane, 1955), the pentose cycle reactions (Cochrane, Peck, and Harrison, 1953; Ganguly and Roy, 1956; Maitra and Roy, 1959), and the Krebs cycle (Cochrane and Peck, 1953; Nickerson and Ram Mohan, 1953; Ganguly and Roy, 1955). However, the pathway of hydrogen (electron) transfer to molecular oxygen has never been studied in detail. Sato (1940) first reported the presence of cytoehromes in the Actinomyeetes. On the basis of a spectroplhotometric survey of the cytochrome components in 13 Streptomyces species, Heim, Silver, and Birk (1957) concluded that a b-type cytochrome is always present, but in no case were they able to detect cytochrome a and in some species cytochrome c was also apparently missing. They suggested that these organisms may have an atypical respiratory chain that terminates with cytochrome b, and this view was subsequently supported by the partial purification of an autoxidizable b-component from extracts of Streptomyces fradiae (Birk, Silver, and Heim, 1957). These findings are not in accord with the spectroscopic observations of Inoue (1958), who detected a-, b-, and c-type cytochromes in mycelium of Streptomyces griseus. We have verified this observation using cell-free extracts of various streptomyces (Niederpruem and Hackett, 1959). The present paper reports a more complete characterization of the respiratory chain both