Biodegradation of Basic Violet 3 by Candida krusei isolated from textile wastewater

Area of Science:

• Environmental Microbiology
• Biotechnology

Background:

• Basic Violet 3 (BV) is a widely used synthetic colorant in textiles, posing environmental challenges due to its recalcitrance to biodegradation.
• The yeast Candida krusei cannot utilize BV as a sole carbon source, necessitating the exploration of cosubstrates for effective decolorization.

Purpose of the Study:

• To investigate the potential of Candida krusei for decolorizing Basic Violet 3 (BV).
• To evaluate the efficacy of various cosubstrates and nutrient sources in enhancing BV decolorization.
• To elucidate the biodegradation pathway and identify key enzymes involved in BV decolorization.

Main Methods:

• Screening of cosubstrates (glucose, sucrose, lactose, maltose, yeast extract, peptone, urea, ammonium sulphate) for BV decolorization by Candida krusei.
• Optimization of conditions using sugarcane bagasse extract as a nutrient source.
• Analysis of BV biodegradation using UV-visible, FTIR, and HPLC.
• Isolation and identification of degradation products.
• Enzyme activity assays (lignin peroxidase, laccase, tyrosinase, NADH-DCIP reductase, MG reductase, azoreductase).

Main Results:

• Maximum decolorization of 74% was achieved with sucrose supplementation.
• 100% decolorization of BV was accomplished within 24 hours using sugarcane bagasse extract as the sole nutrient source.
• Six degradation products were identified, indicating a biodegradation pathway involving stepwise reduction and demethylation.
• Significant increases in NADH-DCIP reductase and laccase activities were observed post-decolorization.

Conclusions:

• Candida krusei demonstrates significant potential for decolorizing the textile dye Basic Violet 3 (BV).
• Sugarcane bagasse extract serves as an effective and inexpensive nutrient source for complete BV decolorization.
• The study elucidates the biodegradation mechanism and highlights the role of specific enzymes in the process, offering a sustainable bioremediation strategy.