Effect of nickel-cobaltite nanoparticles on production and thermostability of cellulases from newly isolated thermotolerant Aspergillus fumigatus NS (class: Eurotiomycetes).

In the present study, effect of nickel-cobaltite (NiCo2O4) nanoparticles (NPs) was investigated on production and thermostability of the cellulase enzyme system using newly isolated thermotolerant Aspergillus fumigatus NS belonging to the class Euratiomycetes. The NiCo2O4 NPs were synthesized via hydrothermal method assisted by post-annealing treatment and characterized through X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. In the absence of NPs in the growth medium, filter paper cellulase (FP) activity of 18 IU/gds was achieved after 96 h, whereas 40 % higher FP activity in 72 h was observed with the addition of 1 mM concentration of NPs in the growth medium. Maximum production of endoglucanase (211 IU/gds), β-glucosidase (301 IU/gds), and xylanase (803 IU/gds) was achieved after 72 h without NPs (control), while in the presence of 1 mM concentration of NPs, endoglucanase, β-glucosidase, and xylanase activity increased by about 49, 53, and 19.8 %, respectively, after 48 h of incubation, against control, indicating a substantial increase in cellulase productivity with the addition of NiCo2O4 NPs in the growth medium. Crude enzyme was thermally stable for 7 h at 80 °C in presence of NPs, as against 4 h at the same temperature for control samples. Significant increase in the activity and improved thermal stability of cellulases in the presence of the NiCo2O4 NPs holds potential for use of NiCo2O4 NPs during enzyme production as well as hydrolysis. From the standpoint of biofuel production, these results hold enormous significance.