LAUSR

The antibacterial activity of potassium metabisulphite, potassium benzoate, potassium propionate, and potassium nitrate were evaluated against 15 species of bacteria using diffusion and microdilution methods. Potassium metabisulphite showed the greatest activity (MIC varied in the range of 0.78 mg ml–1 to 3.12 mg ml–1), then potassium benzoate (6.25 mg ml–1 to 12.5 mg ml–1) followed by potassium propionate and potassium nitrate (6.25 mg ml–1 to 100 mg ml–1). Effects of potassium benzoate, potassium propionate, and potassium nitrate on the sugar fermentation, the effect of potassium benzoate on cell membrane permeability and on amylolytic activity of bacteria were tested. The results indicated inhibition of fermentation, loss of intracellular macromolecules (proteins) from treated cells, and inhibition of amylolytic activity.