Extractive Bioconversion of Gamma-Cyclodextrin and Recycling of Cyclodextrin Glycosyltransferase in Liquid Biphasic System Using Thermo-Separating Polymer.

Yu Kiat Lin,Mohamad Suffian Bin Mohamad Annuar,Yee Jiun Yap,Oi Ming Lai,Tau Chuan Ling,Eng Poh Ng,Pau Loke Show,Arbakariya Ariff

doi:10.3389/fchem.2018.00448

Abstract

An extractive bioconversion conducted on soluble starch with cyclodextrin glycosyltransferase (CGTase) enzyme in ethylene oxide-propylene oxide (EOPO)/potassium phosphates liquid biphasic system (LBS) to extract gamma-cyclodextrin (γ-CD) was examined. A range of EOPO (with potassium phosphates) molecular weights was screen to investigate the effect of the latter on the partioning efficency of CGTase and γ-CD. The results show that the optimal top phase γ-CD yield (74.4%) was reached in 35.0% (w/w) EOPO 970 and 10.0% (w/w) potassium phosphate with 2.0% (w/w) sodium chloride. A theoretical explanation for the effect of NaCl on γ-CD was also presented. After a 2 h bioconversion process, a total of 0.87 mg/mL concentration of γ-CD was produced in the EOPO/ phosphates LBS top phase. After the extraction of top phase from LBS, four continuous repetitive batches were successfully conducted with relative CGTase activity of 1.00, 0.86, 0.45, and 0.40 respectively.

Highlights

In this study, liquid biphasic system (LBS) extractive bioconversion was carried out to split the target product and the biocatalyst into top phase and bottom phases, partitioning target biomolecules into one of the phases
ethylene oxide-propylene oxide (EOPO) 970/potassium phosphate in tie-line lengths (TLLs) of 54.6% (w/w) was selected for the following experiments since it exhibited the optimal condition for highest YT of γ-CD with low KCGTase
EOPO polymer has been applied to the LBS extractive bioconversion of γ-CD

Summary

Introduction

Liquid biphasic system (LBS) extractive bioconversion was carried out to split the target product and the biocatalyst into top phase and bottom phases, partitioning target biomolecules into one of the phases. Gamma-cyclodextrin’s recovery (γ-CD) by LBS was improved by building a recyclable LBS in which the polymer PEGs were substituted through the use of the copolymer ethylene oxide-propylene oxide (EOPO). After heating the system above a certain temperature, the EOPOs split up into two phases, allowing the recovery and reutilization of polymers in subsequent LBS This novel investigation on the CGTase recovery will bring about a simplification of the CGTase purification steps as well as a reduction in the cost incurred on the environment (Johansson et al, 1999; Dembczynski et al, 2010)

Methods

Results

Conclusion