SCREENING OF YEAST ABILITY TO DECOLORIZATION AND COMPLETE BIODEGRADATION OF MALACHITE GREEN TEXTILE DYE AND INVESTIGATION OF THEIR PHYTOTOXICITY

Abstract

Malachite green accumulation in water causes harmful effects. Biodegradation by microbes was the preferred technique used to remove dyes from wastewater. Thirty yeasts were investigated for their ability to remove 50 mg of dye and belonged to: Deboryomyces, Diutina, Papiliotrema, Rhodotorula, and Saccharomyces. Based on the decolorization index (DI) of the examined yeast on the solid medium, the decolorization activity may be classified as highest, moderate and low decolorization activity with DI 1.66-2.78, 1-1.64, and <1 respectively. Rhodotorula mucilaginosa AUMC13567, R. mucilaginosa AUMC13570, Saccharomyces cerevisiae 11688, R. mucilaginosa KR264902, S. cerevisiae C3, and Diutina rugosa AUMC13571 possess the highest decolorization percentages in broth media: 98.41%, 96.65%, 96.49%, 95.59%, 92.80%, and 92.22%, respectively. The decolorization rate is influenced by time, however, yeast cell optical density has no bearing on this rate. The Fourier Transform Infrared Spectroscopy Analysis (FTIR) results of MG before and after degradation indicate a reduction of peaks along the fingerprint region, which can be attributed to the loss of aromaticity of the metabolites, which also confirm degradation by yeast strains. The effect of malachite green dye and its degradation metabolites by five selected yeasts was studied on wheat (T. aestivum), sorghum (Sorghum bicolor), maize (Zea mays), and radish (Raphanus sativus) seed germination, and results show that the germination index of seeds in untreated malachite green solution was significantly low compared to its degradation metabolites by selected yeasts and yeast efficiency in the reduction and elimination of the dye&#039;s toxic effect on these seeds and grains.