Figure 6. Effect of S. aureus nos mutation on carotenoid pigmentation.

A: UAMS-1 (pMK4; wild-type), KR1010 (pMK4; nos mutant), KR1010 (pMKnos; nos complement), and KR1010 (pMKpdt; nos mutant containing pdt complement plasmid) were grown for 48 hours at 37°C on TSA plates. Pigments from each culture were extracted with methanol, the A_{465 nm} of each sample was measured, and standardized by dividing by the sample's corresponding relative OD₆₀₀ value (measured prior to methanol extraction step). Results represent the average of n = 3 independent experiments, error bars  =  SEM. *statistical significance compared to UAMS-1 (pMK4) (p<0.05, Student-Newman-Keuls Test). B: Total RNA from 28 hour TSA plate cultures of UAMS-1 (pMK4), nos::erm mutant (pMK4), nos complement and pdt complement strains (n = 3 biological replicates each) was reversed-transcribed to cDNA, and subjected to quantitative real-time PCR using primers specific for detecting nos, pdt, asp23, crtN, and purH expression. The Livak (2^-ΔΔCt) method was used to determine relative fold change expression of each gene, using measured sigA expression as the reference gene and the UAMS-1 (pMK4) sample as the calibrator.