Figure 3.
Effect of overproduction of ScyA on activities of the cytochrome c oxidase in test strains by the Nadi assay. The method is based on the rapid formation of indophenol blue from colorless a-naphthol catalyzed by cytochrome c oxidase, using N′,N′-dimethyl-p-phenylenediamine monohydrochloride as an exogenous electron donor. Nadi-positive and -negative strains were photographed 1 and 30 min after the reaction, respectively. The wild-type and Δcco strains serve as positive and negative controls. Mutants showing a distinct phenotype have been successfully complemented previously. Strains without overproducing ScyA contain the empty vector. ΔpetC represents the mutant carrying a copy of pet which is integrated for complementation.