FIGURE 4.

Effect of ΔcsoR on cytochrome c oxidase and tyrosinase activity in S. lividans 1326. A,1000 spores were spotted on MM agar plates and incubated for 50 h at 30 °C. The in vivo activity of cytochrome c oxidase was determined using N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) by monitoring the production of the blue compound. The ΔcsoR mutant displays a quicker production of the blue compound than the wild type both on plates with and without added Cu(II). B, tyrosinase activity in the spent medium was determined with 3,4-dihydroxy-l-phenylalanine as substrate at the indicated time points and normalized for the biomass. The average tyrosinase activity of four transformants is plotted.