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Application of ZnO Nanoparticles for Improving the Thermal and pH Stability of Crude Cellulase Obtained from Aspergillus fumigatus AA001.

Srivastava N, Srivastava M, Mishra PK, Ramteke PW - Front Microbiol (2016)

Bottom Line: Cellulases are the enzymes which are responsible for the hydrolysis of cellulosic biomass.The crude thermostable cellulase has been obtained from the Aspergillus fumigatus AA001 and treated with ZnO nanoparticle which shows thermal stability at 65°C up to 10 h whereas it showed pH stability in the alkaline pH range and retained its 53% of relative activity at pH 10.5.These findings may be promising in the area of biofuels production.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Engineering, Sam Higginbottom Institute of Agriculture Technology & SciencesAllahabad, India; Department of Chemical Engineering and Technology, Indian Institute of Technology (Banaras Hindu University)Varanasi, India.

ABSTRACT
Cellulases are the enzymes which are responsible for the hydrolysis of cellulosic biomass. In this study thermal and pH stability of crude cellulase has been investigated in the presence of zinc oxide (ZnO) nanoparticles. We synthesized ZnO nanoparticle by sol-gel method and characterized through various techniques including, X-ray Diffraction, ultraviolet-visible spectroscope, field emission scanning electron microscope and high resolution scanning electron microscope. The crude thermostable cellulase has been obtained from the Aspergillus fumigatus AA001 and treated with ZnO nanoparticle which shows thermal stability at 65°C up to 10 h whereas it showed pH stability in the alkaline pH range and retained its 53% of relative activity at pH 10.5. These findings may be promising in the area of biofuels production.

No MeSH data available.


Thermal stability of ZnO nanoparticles (7.5 μg/mL) treated cellulase at different temperatures.
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Figure 4: Thermal stability of ZnO nanoparticles (7.5 μg/mL) treated cellulase at different temperatures.

Mentions: Further, the thermal stability of 7.5 μg/mL ZnO nanoparticles treated cellulases was tested for 5–12 h at different temperature ranges from 60 to 100°C. The results showed that ZnO nanoparticles treated cellulase showed its half-life for 10 h at 65°C, whereas the same retained ~76% and 64% of relative activity for 8 and 9 h, respectively. However, it maintained ~96, 89, and 82 for 5, 6, and 7 h of incubation (with significance level of 1.0%) (Figure 4). However, the relative activity of the enzyme was observed to be decrease and it retained ~38 and 24% for 11 and 12 h. In contrast, the nanoparticle-treated cellulase retained its 56, 46, and 38% of relative activity at 75°C after the incubation of 6, 7, and 8 h, respectively. Additionally, the same owned 31, 20, 10, and 7% stability after the incubation of 9, 10, 11, and 12 h, respectively. Nevertheless, at 100°C, the ZnO nanoparticles treated cellulase reflects its 4 and 0% of relative activity after 5 and 6 h of incubation (with the significance level of 1.0%). These results clearly indicate the potential of ZnO nanoparticles to improve the stability of crude cellulase at higher temperatures for longer duration. When compare to control, the ZnO nanoparticles treated cellulase showed 2.5 times better stability. The biocompatibility and the isoelectric point could the most appropriate reason to elucidate this phenomenon. Biocompatibility is a well-known concept to improve the stability of the enzyme. Apart from the biocompatibility, other fascinating properties of ZnO nanoparticles such as wide band gap, high exciting binding energy, and quantum effects may also support to make it an ideal candidate for improving the stability of cellulase enzyme. Moreover, since the hexagonal wurtzite structure of ZnO nanoparticles is thermodynamically stable, it may be helpful to influence the thermal stability of crude cellulase enzymes (Ashrafi and Jagadish, 2007; Anders et al., 2015). Thus, use of such type of thermally stable ZnO nanoparticles treated cellulase can improve the economics of market involved in the enzyme-based hydrolysis of biomass, because the enzymatic degradation of cellulose needs the high enzyme loading which increases the production cost as well as economic demands. Since the ZnO nanoparticles treated cellulase are thermally stable for longer duration, so enzymatic bioconversion related issues like incomplete hydrolysis, high enzyme loading, low yield can be avoided. Besides, biofuels, the ZnO-treated cellulase may also serve for the industries involved in the fibers processing and textiles that require reactions at elevated temperatures for long duration (Vyas and Lachke, 2003; Srivastava et al., 2015b).


Application of ZnO Nanoparticles for Improving the Thermal and pH Stability of Crude Cellulase Obtained from Aspergillus fumigatus AA001.

Srivastava N, Srivastava M, Mishra PK, Ramteke PW - Front Microbiol (2016)

Thermal stability of ZnO nanoparticles (7.5 μg/mL) treated cellulase at different temperatures.
© Copyright Policy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4834293&req=5

Figure 4: Thermal stability of ZnO nanoparticles (7.5 μg/mL) treated cellulase at different temperatures.
Mentions: Further, the thermal stability of 7.5 μg/mL ZnO nanoparticles treated cellulases was tested for 5–12 h at different temperature ranges from 60 to 100°C. The results showed that ZnO nanoparticles treated cellulase showed its half-life for 10 h at 65°C, whereas the same retained ~76% and 64% of relative activity for 8 and 9 h, respectively. However, it maintained ~96, 89, and 82 for 5, 6, and 7 h of incubation (with significance level of 1.0%) (Figure 4). However, the relative activity of the enzyme was observed to be decrease and it retained ~38 and 24% for 11 and 12 h. In contrast, the nanoparticle-treated cellulase retained its 56, 46, and 38% of relative activity at 75°C after the incubation of 6, 7, and 8 h, respectively. Additionally, the same owned 31, 20, 10, and 7% stability after the incubation of 9, 10, 11, and 12 h, respectively. Nevertheless, at 100°C, the ZnO nanoparticles treated cellulase reflects its 4 and 0% of relative activity after 5 and 6 h of incubation (with the significance level of 1.0%). These results clearly indicate the potential of ZnO nanoparticles to improve the stability of crude cellulase at higher temperatures for longer duration. When compare to control, the ZnO nanoparticles treated cellulase showed 2.5 times better stability. The biocompatibility and the isoelectric point could the most appropriate reason to elucidate this phenomenon. Biocompatibility is a well-known concept to improve the stability of the enzyme. Apart from the biocompatibility, other fascinating properties of ZnO nanoparticles such as wide band gap, high exciting binding energy, and quantum effects may also support to make it an ideal candidate for improving the stability of cellulase enzyme. Moreover, since the hexagonal wurtzite structure of ZnO nanoparticles is thermodynamically stable, it may be helpful to influence the thermal stability of crude cellulase enzymes (Ashrafi and Jagadish, 2007; Anders et al., 2015). Thus, use of such type of thermally stable ZnO nanoparticles treated cellulase can improve the economics of market involved in the enzyme-based hydrolysis of biomass, because the enzymatic degradation of cellulose needs the high enzyme loading which increases the production cost as well as economic demands. Since the ZnO nanoparticles treated cellulase are thermally stable for longer duration, so enzymatic bioconversion related issues like incomplete hydrolysis, high enzyme loading, low yield can be avoided. Besides, biofuels, the ZnO-treated cellulase may also serve for the industries involved in the fibers processing and textiles that require reactions at elevated temperatures for long duration (Vyas and Lachke, 2003; Srivastava et al., 2015b).

Bottom Line: Cellulases are the enzymes which are responsible for the hydrolysis of cellulosic biomass.The crude thermostable cellulase has been obtained from the Aspergillus fumigatus AA001 and treated with ZnO nanoparticle which shows thermal stability at 65°C up to 10 h whereas it showed pH stability in the alkaline pH range and retained its 53% of relative activity at pH 10.5.These findings may be promising in the area of biofuels production.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Engineering, Sam Higginbottom Institute of Agriculture Technology & SciencesAllahabad, India; Department of Chemical Engineering and Technology, Indian Institute of Technology (Banaras Hindu University)Varanasi, India.

ABSTRACT
Cellulases are the enzymes which are responsible for the hydrolysis of cellulosic biomass. In this study thermal and pH stability of crude cellulase has been investigated in the presence of zinc oxide (ZnO) nanoparticles. We synthesized ZnO nanoparticle by sol-gel method and characterized through various techniques including, X-ray Diffraction, ultraviolet-visible spectroscope, field emission scanning electron microscope and high resolution scanning electron microscope. The crude thermostable cellulase has been obtained from the Aspergillus fumigatus AA001 and treated with ZnO nanoparticle which shows thermal stability at 65°C up to 10 h whereas it showed pH stability in the alkaline pH range and retained its 53% of relative activity at pH 10.5. These findings may be promising in the area of biofuels production.

No MeSH data available.