Fig. 4.
Influence of ggdef-encoding gene overexpression in the WT and the ΔqseB mutant on protease production of A. hydrophila SSU. The data were normalized to 1×108 c.f.u. to account for any minor differences in the growth rates between the various bacterial strains. The results were reproduced in three independent experiments, and the error bars represent sd. Asterisks (***) indicate statistically significant differences in protease activity between the WT and WT overexpressing the ggdef-encoding gene (P≤0.0001), WT and the ΔqseB mutant (P≤0.0001), and the ΔqseB mutant and the ΔqseB mutant overexpressing the ggdef-encoding gene (P≤0.0001) by Student’s t test.