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 eco-
friendly utilization of potato wastewater.
