Figure 3. Post extract effect of PGPE (10 μg/ml) on P. aeruginosa.

‘Control’ in this figure is the vehicle control (0.5%v/v DMSO), which did not exert any effect on growth and pigment production of P. aeruginosa. ( A) Effect of PGPE on growth and QS-regulated pigment production in P. aeruginosa after subculturing of cells in PGPE-free media. Bacterial growth was measured as OD ₇₆₄; OD of pyoverdine was measured at 405 nm, and Pyoverdine Unit was calculated as the ratio OD ₄₀₅/OD ₇₆₄ (an indication of pyoverdine production per unit of growth), Pyocyanin Unit was calculated as the ratio OD ₅₂₀/OD ₇₆₄ (an indication of pyocyanin production per unit of growth). ( B) PGPE-treatment reduces the virulence of P. aeruginosa towards C. elegans even after subculturing of cells in PGPE-free media. Catechin (50 μg/ml) and gentamicin (0.1 μg/ml) employed as a positive controls conferred 100% and 80% protection on worm population respectively; DMSO present in the ‘vehicle control’ at 0.5%v/v did not affect virulence of the bacterium towards C. elegans; DMSO (0.5%v/v) and PGPE at tested concentrations showed no toxicity towards the worm. *p<0.05 , **p<0.01 , ***p<0.001; AS, antibiotic susceptibility; QS, quorum sensing; PGPE, Punica granatum peel extract.