FIG 2.

Phenotypic comparison of wild-type S. venezuelae and the Δrnc and Δrnj mutants. (A) Colony morphologies of wild-type (WT) S. venezuelae and RNase mutants (carrying the integrating plasmid vector pIJ82) and the corresponding complemented strains grown on MYM agar medium for 4 days. The inset image shows the underside of the plate to the left, bearing the rnj mutant and wild-type-complemented mutant strains in the same order and orientation as that for the larger rnj panel (mutant, bottom left; wild type, top; complemented, bottom right), showing relative levels of the brown melanin pigment. (B) Comparison of growth rates and transitions between life cycle stages of wild-type, Δrnj, and Δrnc strains. Cultures were inoculated to an OD₆₀₀ of 0.05 and incubated with shaking at 30°C for 34 h. The optical density (OD₆₀₀) was measured at the indicated times, and life cycle stages (indicated below the graph) were assessed using light microscopy. Each OD₆₀₀ value represents an average from three to four replicates; the standard error for growth density was calculated at each time point.