Title Kinetic characterization of laccase from Bacillus atrophaeus, and its potential in juice clarification in free and immobilized forms
Author Lokesh Kumar Narnoliya1, Neera Agarwal1,2, Satya N. Patel1,2, and Sudhir P. Singh*1
Address 1Center of Innovative and Applied Bioprocessing, S.A.S. Nagar, Mohali-140 306, India, 2Panjab University, Chandigarh, India
Bibliography Journal of Microbiology, 57(10),900–909, 2019,
DOI 10.1007/s12275-019-9170-z
Key Words laccase, Bacillus atrophaeus, immobilization, magnetic nanoparticles, fruit juice clarification
Abstract In the present study, a laccase gene (BaLc) from a lignin degrading bacterium, Bacillus atrophaeus, has been cloned and expressed in Escherichia coli. The optimal catalytic activity of the protein was achieved at 5.5 pH and 35°C temperature, measured by oxidation of ABTS. The Km and Vmax values were determined as 1.42 mM and 4.16 μmole/min, respectively. To achieve the enzyme recovery, the biocatalyst (BaLc) was covalently attached onto the functionalized iron magnetic-nanoparticles. The nanoparticles were characterized by zeta-potential and FTIR analyses. The immobilized BaLc enzyme was physico-kinetically characterized, exhibiting retention of 60% of the residual activity after ten reaction cycles of ABTS oxidation. The immobilized biocatalyst system was tested for its biotechnological exploitability in plant juice processing, achieving 41–58% of phenol reduction, 41–58% decolorization, 50–59% turbidity reduction in the extracts of banana pseudo-stem and sweet sorghum stalk, and apple fruit juice. This is the first study to demonstrate the use of nanoparticle- laccase conjugate in juice clarification. The findings suggest that B. atrophaus laccase is a potential catalytic tool for plant juice bioprocessing activities.