Figure 1: The impact of S. aureus csp homologs on carotenoid production and σ^B activity.

(A) Carotenoid was extracted from each of three biological replicates of S. aureus SH1000 wildtype and csp mutant strains that were grown overnight on tryptic soy agar. These levels were normalized to cell density and compared to one another as a percentage of wildtype. The experiments were performed thrice at different days, with consistent data within each experiment, but showing variation between experiment. Accordingly, percentages from one representative experiment were displayed. The cspA+ strain denotes the cspA complement mutant strain ALC8212, and cspB::aphA indicates the cspB mutant strain ALC8581.

(B) GFP fluorescence generated from σ^B-dependent asp23 promoter was measured for S. aureus SH1000 wildtype, ΔsigB and csp mutant strains transformed with the plasmid pALC2201 carrying the asp promoter driving gfp, at 4 and 10 hours of growth in TSB. Cell densities were simultaneously measured at OD₆₅₀, and fluorescence was normalized to this value. The experiments were performed using three biological replicates and repeated three times. A representative experiment is displayed.

The asterisks in Fig. 1A and 1B indicate statistical significance between wildtype and mutant strains, determined using Student t-test (*, P < 0.05; **, P < 0.005).