Decolouration of Crystal Violet by Immobilized and Free Cells of Pseudomonas aeruginosa

This investigation was aimed at ascertaining the effects of pH, effect of temperature and effect of sodium acetate concentration on crystal violet decolouration by immobilized and free cells of Pseudomonas aeruginosa in a nutrient. The immobilized cells were immobilized sodium alginate solution, agarose and agar in a shaking flask at a speed of 120 revolution/second. Although four dyes were initial selected for the preliminary stage of the study, detailed investigation was carried out using the crystal violet. Prior to inoculation with the respective cells and every 24 h for 120 h, aliquot samples were taken for the estimation of dye using standard procedures. The results revealed highest decrease in the concentration of crystal violet in the presence of the cells was observed at incubation temperature of 35°C. The optimum pH for crystal violet decolouration was shown to be between 8 and 10. Despite the highest decrease in crystal violet concentration in presence of the cells being observed at pH 8 and 10, the decreases did not differ significantly at the different pH. At the different sodium acetate concentrations used in the media, highest decreases in crystal violet concentration in presence of the respective cells was observed at 20 g/L. The present study was able to provide information on the role of the immobilized and free cells of the test bacterial in crystal violet decolouration under the conditions investigated.