Open Access

ARTICLE

Biosynthesis of raw starch degrading β-cyclodextrin glycosyltransferase by immobilized cells of Bacillus licheniformis using potato wastewater

by YASSER S. MOSTAFA^1,*, SAAD A. ALAMRI^1,2, SULIMAN A. ALRUMMAN¹, TAREK H. TAHA³, MOHAMED HASHEM^1,4, MAHMOUD MOUSTAFA^1,5, LAMIAA I. FAHMY⁶

1 Department of Biology, College of Science, King Khalid University, Abha, 9004, Saudi Arabia
2 Prince Sultan Bin Abdulaziz Center for Environmental and Tourism Research and Studies, King Khalid University, Abha, 9004, Saudi Arabia
3 Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, City of Scientific Research & Technological Applications, New Borg El-Arab City, 21934, Egypt
4 Department of Botany and Microbiology, Faculty of Science, Assiut University, Assiut, 71515, Egypt
5 Department of Botany and Microbiology, Faculty of Science, South Valley University, Qena, 83523, Egypt
6 Department of Microbiology and Immunology, Faculty of Pharmacy, October University for Modern Science and Art, Giza, 12451, Egypt

* Corresponding Author: Yasser S. Mostafa,

BIOCELL 2021, 45(6), 1661-1672. https://doi.org/10.32604/biocell.2021.016193

Received 16 February 2021; Accepted 23 April 2021; Issue published 01 September 2021

Abstract

The study was sought to enhance the synthesis of thermal stable β-cyclodextrin glycosyltransferase (β-CGTase) using potato wastewater as a low-cost medium and assess the degree to which it is efficient for industrial production of β-cyclodextrin (β-CD) from raw potato starch. Thermophilic bacteria producing β-CGTase was isolated from Saudi Arabia and the promising strain was identified as Bacillus licheniformis using phylogenetic analysis of the 16S rRNA gene. Alginate-encapsulated cultures exhibited twice-fold of β-CGTase production more than free cells. Scanning electron microscopy (SEM) of polymeric capsules indicated the potential for a longer shelf-life, which promotes the restoration of activity in bacterial cells across semi-continuous fermentation of β-CGTase production for 252 h. The optimal conditions for β-CGTase synthesis using potato wastewater medium were at 36 h, pH of 8.0, and 50°C with 0.4% potato starch and 0.6% yeast extract as carbon and nitrogen sources, respectively. The purified enzyme showed a specific activity of 63.90 U/mg with a molecular weight of ∼84.6 kDa as determined by SDS-PAGE analysis. The high enzyme activity was observed up to 60°C, and complete stability was achieved at 75°C. High levels of activity and stability were shown at pH 8.0, and the pH range from 7.0–10.0, respectively. The enzyme has an appreciable affinity for raw potato starch with a Km of 5.7 × 10⁻⁶ M and a Vmax of 87.71 µmoL/mL/min. β-CD production was effective against 25 U/g of raw potato starch. The outcomes demonstrated its feasibility to develop a fermentation process by integrating the cost-effective production of β-CGTase having distinctive properties for β-CD production with ecofriendly utilization of potato wastewater.

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