Screening and optimization of laccase from cyanobacteria with its potential in decolorization of anthraquinonic dye Remazol Brilliant Blue R

In the present study 35 heterocystous and non heterocystous strains of cyanobacteria has been investigated for laccase production. Among all selected strain 29 strains showed the positive results and Spirulina platensis CFTRI gave the highest laccase activity. The laccase production was found to be maximum on 10(th) day under normal growth condition. The average time of laccase production was decreased to 4(th) day in presence of inducer guaiacol. The combination of (2,5-Xylidine + guaicol) act as best inducer that enhanced the laccase production 36.2 folds (582.92 Uml(-1)) due to synergistic effect. The optimum condition for laccase production was 30 degrees C & pH 9, glucose as carbon source and sodium nitrate as nitrogen source. The enzyme preparation was done by cold acetone precipitation and further characterized through SDS-PAGE and activity staining using ABTS as substrate. The molecular weight of protein was approximate to 66KDa. The crude laccase showed 46.74% decolorization of anthaquinonic dye RBBR within 48 h, The rate of decolorization was increased to 63.61% & 89.90% in presence of redox mediator (1-hydroxybenzotriazole & syringaldehyde) which suggested that biological methods using laccase are generally considered environmentally friendly as they can lead to complete degradation of organic pollutants at low cost.