Azo dyes are the synthetic dyes that consists of –N=N– bond which is stable in nature making them highly toxic to the biological system. Due to the xenobiotic characteristics, removal of unpleasant colour and related toxicity is essential. In this study, two bacteria isolated from Sungai Lembing hot springs (Achromobacter marplatensis and Aquamicrobium defluvii) and a white-rot fungus (Ganoderma lucidum) were tested for their decolourization potential. The microbes were developed in minimal salt medium (MSM) supplemented with co-substrate (glucose) and 100 mg/L methyl red dye under 30oC and 37oC with agitation for the decolorization treatment. The dye decolourization rate was spectrophotometrically determined within 3 stipulated treatment days for both temperatures and the colour changes between those samples were observed. On the account of decolorizing ability, all tested samples shown decolourization potential, and among them the most efficient was Ganoderma lucidum. G. lucidum effectively decolorized methyl red dye with 64.14% and 33.01% at 30oC and 37oC, respectively. The other strains, Achromobacter marplatensis and Aquamicrobium defluvii were effective at 37oC with the decolorizing efficiency of 29.18% and 6.04%, respectively. Further comparative analysis of all metabolites and control through the FTIR depicted a slight change of functional groups of the methyl red dye, indicating the biodegradation activity of the samples. Thus, this study showed G. lucidum had higher potential for methyl red dye decolourization in both different temperatures compared to the hot springs’ bacteria, hence indicates its potential to be used in the industrial effluents treatment containing azo dye.
Keywords: Methyl red, decolorization, biodegradation, biosorption, azo bond, Achromobacter marplatensis, Aquamicrobium defluvii, Ganoderma lucidum