Immobilization of cellulase on iron tolerant Pseudomonas stutzeri biosynthesized photocatalytically active magnetic nanoparticles for increased thermal stability.

Bacteria mediated synthesis of magnetic nanoparticles (MNPs) for biotechnological applications is an important area of nanotechnology. This study demonstrates the use of iron tolerant bacterium for synthesis of MNPs for cellulase immobilization and photocatalytic activity. The enrichment, isolation, screening and molecular identification led to the selection of Pseudomonas stutzeri KDP_M2 with high degree of iron tolerance. The synthesis parameters such as 1 mM ferric quinate, pH 9 and 96 h static incubation were found optimum for maximum yield of 210 mg/L. The characterization using various techniques indicated that MNPs were Hematite (Fe2O3) with particle size between 10 and 20 nm. Further, vibrating sample magnetometer and thermogravimetric analyses demonstrated the superparamagnetic nature with high thermal stability. The MNPs were found an excellent support for immobilization of industrially important cellulase with 96.5% binding efficiency. The immobilization which was confirmed by Fourier transform infrared spectroscopy indicated that immobilization did not reduce the cellulase activity, rather enhanced the thermal stability and operational temperature range of cellulase. The immobilized cellulase showed maximum cellulolytic activity at pH 4.6 and retained 80% activity upto 3rd cycle of reuse, therefore, can be utilized repeatedly at acidic conditions.The monitoring the photocatalytic activity showed rapid degradation of methyl violet and methylene blue within initial 10 min. of reaction.