Immobilization of Zymomonas mobilis In situ in Flexible Polyurethane and Potential for Bioconversion in Sodium Maltobionate

Abstract

Maltobionic acid and its salts are produced by the action of the periplasmic enzymatic complex glucose-fructose oxidoreductase (GFOR), and glicono-δ-lactonase (GL) from Zymomonas mobilis and, for such, cell immobilization is outstanding. Thus, the objective of this work was to immobilize, in situ, Z. mobilis cells containing GFOR/GL in flexible polyurethane foam (PU) in order to produce maltobionic acid. In the immobilization, concentrations of polyurethane and biomass support constituents varied, and the visual aspect of the material immobilized was assessed, its enzymatic activity, immobilization yield, and operational stability. In the maximized immobilization condition, morphological analysis of the support and bioconversion runs were performed. The scanning electron microscopy analysis showed that the microorganism was trapped in the PU (7 g of polyol; 3.5 g of isocyanate; 0.02 g of silicone, and 7 g of biomass). The immobilized material maximum enzymatic activity against glucose was 19.40 U g-1dry cell, with an immobilization yield of 60.29% and 15 reuses. In bioconversion, 491.42 mmol L-1 of sodium maltobionate were produced in 47.56 h, with a conversion factor of 0.88 and mass productivity, specific productivity, and specific product formation speed of 2.58 mmol h-1; 1.81 mmol g-1 h-1 and 6.25 mmol g-1 h-1, respectively. This study's results contribute to the production of aldonic acids because it uses scarce information in the area and application potentials.