Biobleaching of waste paper using lignolytic enzyme from Fusarium equiseti VKF2: a mangrove isolate

Abstract

Laccase is a major enzyme used in the paper and pulp industries for bio-bleaching applications. This paper focused on the bio-bleaching property of a potential lignolytic fungus, Fusarium equiseti VKF-2. Optimum conditions for laccase production were tested by statistical models under solid state fermentation using saw dust as substrate. Fusarium equiseti VKF-2 achieved a maximum laccase activity of 305 Ug-1 of substrate. During purification, 67% yield was obtained with 80% ammonium sulphate. The enzyme activity was confirmed through zymogram analysis with 2 active fractions observed at 94 and 75 kDa. Laccase treatment resulted in defibrillations, crack formation and changes in the functional groups of paper pulp. The laccase facilitated the maximum hexenuronic acid release with Kappa number reduction. There was a - brightness of 15% following 4 h of enzymatic treatment. Hence, the present laccase was found to be suitable for the bio-bleaching of newspaper waste via an eco-friendly process.