Fig. 2

Silver modulates biofilm formation, exopolysaccharide synthesis, protein synthesis, and nitrogen metabolism in P. aeruginosa. (A) Silversol could partially inhibit P. aeruginosa biofilm formation, and eradicate the pre-formed biofilm. Crystal violet assay was performed to quantify biofilm formation, and eradication. Cell viability in the biofilm was estimated through MTT assay; (B) Silversol enhances EPS synthesis in P. aeruginosa. Though there are lesser number of cells in the silver-supplemented media, they synthesized EPS in amount equal to their silver-unexposed counterparts. EPS Unit was calculated as Cell Density (OD₇₆₄): EPS (g/L) ratio; (C) P. aeruginosa grown in presence of Silversol registered higher protein synthesis. Intracellular and extracellular protein concentrations in P. aeruginosa grown in presence of Silversol at sub-MIC level were significantly higher as compared to its silver-non-exposed counterpart. Kanamycin employed as a positive control at its sub-MIC level also generated similar response from bacterial culture. Protein Unit (i.e., Protein concentration: Cell density ratio) was calculated to nullify any effect of cell density on protein production; (D) Silversol-treated P. aeruginosa culture has higher extracellular accumulation of nitrite. Silversol caused nitrite concentration in P. aeruginosa culture supernatant to rise when compared to control. Sodium nitroprusside (SNP) used as a positive control also caused higher nitrite build up in P. aeruginosa culture. Nitrite Unit (i.e., Nitrite concentration: Cell density ratio) was calculated to nullify any effect of cell density on nitrite production. *p < 0.05, **p < 0.01, ***p < 0.001, ns: non-significant