Effect of pH on P. aeruginosa PAO1 virulence and pyoverdin production. (A) Survival in mice subjected to hepatectomy and intestinal injection of P. aeruginosa. All mice were drank either water (var. Hep+MPAO1), 25 mM potassium phosphate buffer at pH 6.0 (var. Hep+MPAO1+[Pi] pH 6.0), or 25 mM potassium phosphate buffer at pH 7.5 (var. Hep+MPAO1+[Pi] pH 7.5). Results were reproduced in 3 experiments, n = 16/group, p < 0.05 in between pH7.5 and pH6.0 groups. (B) Survival in C. elegans feeding on P. aeruginosa PAO1 lawns. Results were reproduced in triplicate, n = 63/group, p < 0.05 in between pH7.5 and pH6.0 groups. (C) Pigmentation of P. aeruginosa PAO1 lawns grown at different phosphate and pH levels. The pH shift from 6.0 to 7.5 changes pigmentation on lawns containing Pi 25 mM. However, highly intense pigmentation is observed in P. aeruginosa PAO1 when grown as lawns at low (<0.1 mM) phosphate independent of pH. (D) The enhanced production of pyoverdin under conditions of phosphate limitation is not affected by pH changes.
Romanowski et al. BMC Microbiology 2011 11:212 doi:10.1186/1471-2180-11-212