Polysaccharide-layered double hydroxide-aldolase biohybrid beads for biocatalysed CC bond formation

This study describes the design a novel microbioreactor for the biocatalysed asymmetric synthesis of polyhydroxylated compounds. The bioreactor was elaborated by a hierarchical assembly of a recombinant fructose-6-phosphate aldolase (FSA(wt)), layered double hydroxides (LDH) nanoplatelets and polysaccharide beads. Various polysaccharides were tested to encapsulate FSA(wt) and pre-immobilised FSA(wt) in LDH (FSA(wt)@Mg2Al-LDH). l-Carrageenan appears as the most suitable candidate to prepare biohybrid beads. The retained activities in l-carrageenan beads were measured for both free FSA(wt) and immobilised FSA(wt), revealing a 3 fold higher activity in favour of the pre-immobilised FSA. This result was probably due to a positive interaction between the negatively charged polysaccharide and the positively charged LDH layers. The catalytic activity, the recyclability and the storage of the beads were studied in addition to the leakage of FSAwt activity from beads. Nanostructuration of both FSA(wt)/l-carr and FSA(wt)@Mg2Al-LDH/l-carr was investigated by structural and textural characterization techniques. (C) 2015 Published by Elsevier B.V.