Enhanced Biodegradation of Crystal Violet by Immobilized Cells in Rhodococcus Strain ucc 0004 as Biological Tool

Abstract

Every year million tons of dyes and toxic compounds are discharged as industrial waste which pose a threat to the environment and human health. Thus, environmental concern over discharge of coloured wastewater has been on the rise. A competent method which is environmentally acceptable and economically viable is desired to treat the textile effluent prior to discharge into the environment. In the present study, twenty-three locally isolated Rhodococcus strains were examined as biological tools for decolourization of crystal violet. The tested microorganisms which were locally isolated Rhodococcus strains demonstrated promising ability to decolourize crystal violet as evidenced by the change in the colour of the dye from dark purple to pale purple on nutrient agar plates. One of the best strains namely Rhodococcus strain UCC 0004 formed clear zone around the colonies of the bacteria after 5 days of incubation period. This strain demonstrated good growth and completely decolourized 0.6 mM crystal violets after 5 days of incubation period. Further investigation was carried out by comparing the ability between immobilized cells and whole cells of Rhodococcus strain UCC 0004 for efficient crystal violet removal. The results showed that the percentage of crystal violet decolourization was highest ability to degraded when immobilized cells in gellan gum (99 a ± 0 %) and calcium alginate (98a ± 2 %), were used compared to heat killed cells which yielded (11c ± 0 %) of crystal violet removal. These findings clearly indicated that the immobilized cell of Rhodococcus strain UCC 0004 has a huge potential as biological tool to remediate actual wastewater containing crystal violet.