Unveiling the waxy corn starch as an effective substrate for cyclodextrin glycosyltransferase biosynthesis by...

Efficient cyclodextrin (CD) production still faces limitations related to the selection of fermentative substrates that maximize the biosynthesis of cyclodextrin glycosyltransferase (CGTase). This study addressed this gap by evaluating waxy corn starch (WCS) and arrowroot starch (AS) as alternative substrates in submerged fermentation by Bacillus megaterium, optimizing fermentation parameters to achieve maximum yield, and performing the biochemical characterization of CGTase produced under optimized conditions. WCS demonstrated to be a superior carbon substrate against AS allowing enhanced CGTase secretion. The response surface methodology (RSM) based on central composite rotatable design (CCRD) was applied to optimize key fermentation parameters. Maximum CGTase activity of 17.86 U/mL was reached under 3.07 % WCS, 0.5 % amino acid supplementation, and initial pH 7.56 at 60 h and 35 °C. The CGTase displayed broad thermal and pH stability. Notably, WCS not only improved enzyme yields but also enhanced β-cyclodextrin production efficiency, offering a cost-effective scalable alternative to conventional substrates. Additionally, calcium ions effectively enhanced enzymatic activity and thermostability. This study provides a valuable scientific and biotechnological contributions demonstrating that WCS not only improves CGTase yield but may also offer relevant economic and operational advantages for industrial applications, establishing it as a promising substrate for large-scale cyclodextrin manufacturing.