Encapsulation of fungal extracellular enzyme cocktail in cellulose nanoparticles: enhancement in enzyme stability

Abstract

We demonstrated the nano-immobilization of fungal enzymes through their encapsulation in cellulose nanoparticles (CNPs). An extracellular enzyme cocktail (a mixture of amylase, protease, lipase, and cellulose) was produced from <em>Aspergillus niger</em> and <em>Phanerochaete chrysosporium</em> through submerged fermentation. The process of encapsulation was carried out through a microemulsion nanoprecipitation method in the presence of a lipid, a surfactant, and a co-surfactant. The morphology of CNPs was determined by field-emission scanning electron microscopy and transmission electron microscopy; CNPs were less than 100 nm in diameter. Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy demonstrated the successful encapsulation of the fungal enzyme cocktail and revealed C and O as its major components. FTIR peaks of CNPs with encapsulated enzymes occurred at 3421.80, 2828.91, 1649.29, 1450.24, and 1061.61 cm⁻¹as well as in the range of 1050–1150 cm⁻¹. Encapsulated enzymes showed excellent stability with a peak at −70.91 mV in zeta potential studies. Thermogravimetric analysis proved that the CNP-encapsulated enzymes had an initial weight loss at 250°C. The encapsulated fungal enzyme cocktail exhibited higher catalytic performance and stability than the free enzymes. The encapsulated fungal enzyme cocktail derived from <em>A. niger</em> at the concentration of 100 µg/mL, showed the highest amylase activity with a clear zone of 2.5 cm. Overall, the results of this research reveal the enhancement in the activity of fungal extracellular enzyme cocktail through nanoencapsulation.