Ultrasound processing of amyloglucosidase: impact on enzyme activity, stability and possible industrial applications

Ariana de Souza Soares,Afonso Mota Ramos,Bruno Ricardo de Castro Leite Júnior,Pedro Esteves Duarte Augusto,Camila Archette Nogueira

doi:10.4025/actascitechnol.v43i1.48929

Ariana de Souza Soares, Afonso Mota Ramos + Show 3 more

Open Access

https://doi.org/10.4025/actascitechnol.v43i1.48929

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Abstract

This study evaluated the effect of ultrasound processing as a pre-treatment of amyloglucosidase on the enzymatic activity and stability. The activity was evaluated under optimal (65°C/ pH = 4.5) and non-optimal conditions of temperature and pH and its stability was evaluated during storage at 8°C. The enzyme solution was processed at 9.5 W L-1, 40 kHz, 23°C and at pH 3.5, 4.5, and 5.5, for up to 120 min. The activity was measured at 35, 65 and 80°C. The US process was able to increase, reduce or not alter the enzymatic activity, depending on the conditions applied. These modifications depended on the pH of the enzyme solution, the ultrasound processing time and the activity temperature. In different ultrasound conditions, mainly at 35 and 65°C, the enzyme activity did not change, demonstrating that this technology can be used for other purposes, such as microbial inactivation, without affecting the enzyme. The activity increase (up to 15%) occurred under non-optimal pH and temperature conditions (pH 3.5 or 5.5/ 80°C), suggesting that ultrasound promoted stabilization and enzymatic protection. This result is interesting in the starch saccharification, which requires the enzymatic reaction at high temperatures. Therefore, such results can increase the application range of this enzyme in different industrial applications.

Highlights

It indicates that the high temperature associated with extreme pH promotes the loss of enzymatic activity (Vandersall, Cameron, Nairn, Yelenosky, & Wodzinski, 1995; Liu et al, 2015)
Leaes et al (2013) verified higher products formation during hydrolysis in the ultrasonic bath up to 70°C, whereas, we verified an increase in the enzymatic activity when measured at 80°C after the ultrasonic bath processing at 23°C. These results show that the effects of ultrasound on the Amyloglucosidase/ glucoamylase (AMG) are different when the enzyme solution is processed or when the reaction is performed under ultrasound
The changes depended on the pH of the enzyme solution, processing time and activity temperature

Summary

Introduction

Amyloglucosidase/ glucoamylase (AMG) (EC 3.2.1.3) is an enzyme that hydrolyzes α-1,4 and α-1,6 glycosidic bonds from the non-reducing ends of starch and dextrins, producing glucose (Lin, Felberg, & Clark, 1993). The use of enzymes for large-scale industries presents two obstacles: high production cost and low stability under process conditions that use for example, high temperature, diverse pH values, affecting enzymatic activity. Several alternatives are being developed to minimize these limitations, such as enzyme immobilization, genetic engineering (Patel et al, 2016) and emerging technologies, such as high pressure, microwaves and ultrasound, which began to be studied to promote enzymatic activation and stabilization (Tribst & Cristianini, 2012; Mazinani & Yan, 2016; Dalagnol, Silveira, Silva, Manfroi, & Rodrigues, 2017)

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