International Journal of Waste Resources

Abstract

Evaluation of Methyl Red Tolerant Cyanobacteria for Simultaneous Laccase Production and Dye Decolorization

Mohd Kafeel Ahmad Ansari, Umar Mohteshum Khatib, Gary Owens and Tasneem Fatma

While the textile industries have and will continue to play a vital role in the economic growth of India one unfortunate historic side effect has been the ubiquitous use of synthetic azo dyes which pose potential threat to aquatic environmental ecosystems if effluent from such industries is left untreated. In this study, of the ten cyanobacterial strains tested, six were found to tolerate exposure to a test methyl red (MR) dye well as indicated good cell growth. Further investigation of the concentration of various photosynthetic pigments, and the production of phenol degrading laccase enzymes in the bacteria in the presence of MR dye indicated that all six tolerant strains (Spirulina-C5, Spirulina-C10, Spirulina-C11, Lyngbya, Phormidium and Synechocystis) exhibited a significantly higher concentration (P<0.05) of pigments and significantly higher production (P<0.05) of extracellular proteins in the presence of dye. The best performing strain, Spirulina-C11, produced significantly greater amounts of laccase (59.57 mU/ml) at 10 days relative to all other strains which was further enhanced (71.52 mU/ml) following addition of guaiacol as an inducer. Guaiacol also induced increased protein content that may was attributed to an increase in de nova synthesis of phenol degrading enzymes and stress tolerance proteins. In practice Spirulina-C11 was able to effectively decolorize 65.2% of methyl red solution within 48 hrs.