[Possible role of the respiratory system of Fusidium coccineum in regulating fusidic acid biosynthesis].

The respiration system was studied in three strains of the fungus Fusidium coccineum differing in their capability to synthesize fusidic acid. In all of the three strains, the system of oxidative phoshorylation predominated in supplying the cells with energy. In the strains with low and zero activities, the terminal oxidation of reduced equivalents occurred mainly via the respiration chain with cytochrome oxidase as a terminal component. In the strain with a high activity, there was an alternative cyanide resistant pathway, along with the classical cytochrome chain, and the complete switching to the alternative pathway coincided with the period of the antibiotic maximal accumulation. The induction of the alternative pathway in the strain with a high activity did not involve inhibition of the cytochrome region of the respiration chain. It was shown for the first time that the antibiotic synthesis and the character of cell differentiation can be changed by modifying the pathways of oxidation with specific inhibitors such as chloramphenicol and salicyl hydroxamate. Apparently, there is some general mechanism involved in regulating the production of the antibiotic, cell differentiation, and switching to the alternative oxidative pathway.