DJTU-sh7 strain from Myrothecium verrucaria fungi as an effective and eco-friendly treatment method for utilization of various colouring agents.
Synthetic dyes are ingredients broadly used as colouring agents – their applications range from textile and leather dyeing, paper printing to production of food, drink and pharmaceuticals. Industry produces over 700,000 tons of dyes yearly, releasing large quantities of liquid wastes into rivers and seas, oftentimes without proper treatment. Effluents produced by the industry add to already existing environmental problems and their utilization becomes a major concern.
The use of microorganisms is one of the most popular, cost-effective and eco-friendly alternatives applied to break down environmental pollutants. Treatment methods are diverse, ranging from such processes as chemical oxidation, adsorption, coagulation to biological techniques based on pure cultures, degradative enzymes and activated sludge. The situation is quite different however when it comes to alternatives for biodegradation of various dyes, where not many alternatives are present. Fungal analysis for decolorizing dyes has not been completely researched yet and more extensive studies are required.
The scientists from Chinese Academy of Sciences, Dalian Jiaotong University, Shanghai University of Traditional Chinese Medicine, and Chinese Academy of Medical Sciences examined globally available fungi called Myrothecium verrucaria that produce bioactive enzyme named laccase. Laccase is capable of oxidizing variety of substrates and combines successfully with other enzymes extracted from microbes and plants, becoming an effective tool for dye decomposition. The researchers in their article Functional and Transcriptomic Characterization of a Dye-decolorizing Fungus published in Journal of Microbiology investigated the properties of laccase-producing fungi by isolating their strains from Taxus rhizosphere. Through the use of transcriptome analysis and RNA-Sequencing they found that DJTU-sh7 strain from Myrothecium verrucaria had the highest laccase activity and as a result was the most effective in decolorizing nine reactive dyes. M. verrucaria strain DJTU-sh7 was effective at a broad range of temperature and pH and its ability to successfully decompose dyes was confirmed by chromatographic and spectral analyses.
Biodegradation strategies of toxic substances released into the environment as a consequence of production processes are the top discussion topic of governments, industry and scientists today. However various treatment and decomposition methods are available, some of the synthetic substances still lack their ecological alternatives. Laccase-producing fungi are already employed in diverse industrial fields, being applied for waste water treatment, biomass conversion or polymer syntheses amongst others. The effectiveness of fungi containing DJTU-sh7 indicates their added relevance also in case of dye effluent utilization. It is of high importance that studies similar to the work of Chinese researchers are performed in order to achieve a sustainable, bio-based economy.
The original article is fully available for reading at: https://www.exeley.com/polish_journal_of_microbiology/doi/10.21307/pjm-2018-050