首页|Galactose to tagatose isomerization by the L-arabinose isomerase from Bacillus subtilis: A biorefinery approach for Gelidium sesquipedale valorisation
Galactose to tagatose isomerization by the L-arabinose isomerase from Bacillus subtilis: A biorefinery approach for Gelidium sesquipedale valorisation
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NSTL
Elsevier
Tagatose is a rare sugar with increasing commercial interest as sweetener. Biotechnological production of D- tagatose by enzymatic isomerization of D-galactose provides an alternative to chemical processes. In the last years, L-arabinose isomerases (L-AIs) from different origins have been studied to increase the effectiveness of tagatose production. In this work, the L-AI from Bacillus subtilis, previously reported to have unique substrate specificity for L-arabinose, was expressed in Escherichia coli and studied for isomerization of D-galactose to D-tagatose. The recombinant enzyme demonstrated, for the first time, tagatose bioconversion capacity, reaching similar to 59% conversion. Furthermore, a sustainable tagatose production strategy was developed by using Gelidium sesquipedale red seaweed and its undervalued processing residues as source of galactose. L-AI successfully con-verted the galactose-rich hydrolysate, obtained from direct acid hydrolysis of seaweed, to tagatose (50.9% conversion). Additionally, the process combining autohydrolysis of G. sesquipedale and acid hydrolysis of the remaining residue allowed a full integral valorisation of polysaccharides: 13.33 g of agar, an important hydro-colloid, coupled with the production of 5.97 g of tagatose. These results confirmed that seaweed biomass and waste-derived are promising substrates for tagatose production by L-AI, contributing to the advancement of circular economy and to the actual needs of food industry.
NSTL
Elsevier
