Optimization of environmental parameters on the decolorization of Reactive Brilliant Blue dye by yeast isolates from textile effluent

Abstract

The present study was conducted to investigate the decolorization and degradation of Reactive Brilliant Blue dye using yeasts isolated from the effluent treatment of the textile industries and the identified yeast strains under optimal conditions using the standard methods. Among twenty-four yeast strains, only five yeasts have the ability to decolorize the dye (2.8%). Three yeast strains; Rhodotorula glutinis, Candida utilis(1) and Candida sphaerica as well as the local two yeast isolates which were identified as Rhodotorula rubra and Cryptococcus albidus showing high decolorization rate, they were used for the decolorization of Reactive Brilliant Blue dye in a medium containing glucose and yeast extract as a best carbon and nitrogen sources, the pH of medium varied among the yeasts, C. utilis(1), R. rubra and C. albidus was 4, while C. sphaerica and R. glutinis was 6 and5.5, respectively. All yeast strains were incubated for 18 h at 25˚C except C. utilis(1) at 37˚C. C. utilis(1), R. glutinis and C. sphaerica showed high decolorization rate under static aerobic conditions. While R. rubra and C. albidus showed decolorization under static anaerobic conditions. According to the potentiality of yeast strains; C. sphaerica could achieved a removal ratio of 68.83%, while C. albidus 68.40%, R. rubra 67.75%, R. glutinis 66.88% and C. utilis(1) 63.85% of Reactive Brilliant Blue dye in a concentration of 10 mg/L. The highest biodegradation of the dye by the five yeast strains was confirmed by using plain distilled water as a decolorization medium. In conclusion, yeast strains could be used for the biodegradation of dye- polluted waters including rate of degradation of anthraquinone dye.