| Title | Kinetic characterization of laccase from Bacillus atrophaeus, and its potential in juice clarification in free and immobilized forms |
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| 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. |