Screening of laccase producer from soil and its applications

In present work, twenty-eight bacteria and thirty fungi were isolated from soil on Luria Bertani (LB) Agar at 37ºCin 2-3 days, Potato Dextrose Agar (PDA) at 28±2ºCafter 3days of incubation respectively. From bacterial isolates, three bacteria and three fungi showed intense development of brown color using 1%Tannic acid as a substrate in 3-4 days at 37ºCwhich indicates they were laccase producers and are identified as Pseudomonas aeruginosa, Erwinia chrysantemi, Klebshiella oxytoca, Cladosporium spp. and two Aspergillius spp,. Crude laccase of Klebshiella oxytoca was extracted by centrifugation then partially purified using 40% 8 70% ammonium sulphate precipitation. Partially purified laccase expressed highest activity 980U/ml at pH 7.5 8 30ºCafter 30min of incubation using 1% tannic acid. Immobilization of partially purified laccase was done by entrapment method using sodium alginate. Partially purified and immobilized laccase showed 97% of crystal violet 8 94% neutral red dye degradation in 3 days of incubation as well as meat tenderization. It has antibacterial activity against S. aureus, S.typhi, and Agrobacterium tumifaciens and showed zone of inhibition ranging from 17mm-20mm. Immobilized laccase also synthesized silver nanoparticle at 75ºCin 3-4 hrs. Laccase from Klebshiella oxytoca in our work have wide applications and can be used in bioremediation.