Elsevier

Biotechnology Reports

Volume 17, March 2018, Pages 55-62
Biotechnology Reports

Improvement of Aspergillus flavus saponin hydrolase thermal stability and productivity via immobilization on a novel carrier based on sugarcane bagasse

https://doi.org/10.1016/j.btre.2017.12.007Get rights and content
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Highlights

  • Soyasaponins conversion to soyasapogenol B (SB) by Aspergillus flavus saponin hydrolase (SH).

  • The best SH immobilization carriers were Eupergit C and activated sugarcane bagasse (SCB).

  • Opitmization of SH immobilization conditions on Eupergit C and activated SCB.

  • Compared to free SH, immobilized SH showed higher stability and SB productivity.

  • SCB is a good alternative to Eupergit C as it is more sustainable and an inexpensive.

Abstract

Soyasapogenol B (SB) is known to have many biological activities such as hepatoprotective, anti-inflammatory, anti-mutagenic, antiviral and anticancer activities. Enzymatic conversion of soyasaponins to SB was carried out using saponin hydrolase (SH) extracted from Aspergillus flavus. The partially purified enzyme was immobilized on different carriers by physical adsorption, covalent binding or entrapment. Among the investigated carriers, Eupergit C and sugarcane bagasse (SCB) activated by DIC and NHS were the most suitable two carriers for immobilization (the immobilized forms recovered 46.5 and 37.1% of the loaded enzyme activity, respectively). Under optimized immobilization conditions, immobilized SH on Eupergit C and on activated SBC recovered 87.7 and 83.3% of its original activity, respectively. Compared to free SH, immobilized SH on Eupergit C and on activated SCB showed higher optimum pH, activation energy, half-lives and lower deactivation constant rate. Also, their SB productivities were improved by 2.3- and 2.2-folds compared to free SH (87.7 and 83.3 vs. 37.5%, respectively). Hence, being SCB more sustainable and an inexpensive material, it can be considered a good alternative to Eupergit C as a support for SH immobilization. SH immobilization on industrially applicable and inexpensive carrier is necessary to improve SB yield and reduce its production cost. The chemical structure of SCB and the resulting cellulose derivatives were studied by ATR-IR spectroscopy. The thermal analysis technique was used to study the chemical treatment of SCB and coupling with the enzyme. This technique confirmed the removal of lignin and hemicellulose by chemical treatment of SCB.

Graphical abstract

Course of soyasapogenol B production from soysaponin by free (

) and immobilized A. flavus saponin hydrolase on Eupergit C (
) and functionalized sugarcane bagasse (▲).

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Abbreviations

SH
saponin hydrolase
SB
soyasapogenol B
SCB
sugarcane bagasse

Keywords

Saponin hydrolase
Immobilization
Sugarcane bagasse
Aspergillus flavus

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