Modulation of lipase B from Candida antarctica properties via covalent immobilization on eco-friendly support for enzymatic kinetic resolution of rac-indanyl acetate.

In this study, the modulation of enzymatic biocatalysts were developed by the use of lipase B from Candida antarctica covalently immobilized on an eco-friendly support, cashew apple bagasse, activated with 10% glycidol-ethylenediamine-glutaraldehyde (GEG) under different immobilization strategies (5 mM or 100 mM ionic strength and in absence or presence of 0.5% (v/v) Triton X-100). The biocatalysts were characterized for thermal and organic solvents stabilities and compared with the soluble enzyme. The biocatalysts were then applied to the hydrolysis of the rac-indanyl acetate (2:1 ratio enzyme/substrate) at pH 7.0 and 30 °C for 24 h. For all the strategies evaluated, GEG promoted kinetic resolution of rac-indanyl acetate with maximum conversion (50%) and led to (R)-indanol with excellent enantiomeric excess (97%), maintaining the maximum conversion for five consecutive cycles of hydrolysis. Therefore, the use of cashew apple bagasse has proved to be a promising eco-friendly support for enzyme immobilization, since it resulted in stable biocatalysts for enzymatic kinetic resolution.

Alternative Heterologous Expression of L-Arabinose Isomerase from Enterococcus faecium DBFIQ E36 By Residual Whey Lactose Induction.

This study reports an alternative strategy for the expression of a recombinant L-AI from Enterococcus faecium DBFIQ E36 by auto-induction using glucose and glycerol as carbon sources and residual whey lactose as inducer agent. Commercial lactose and isopropyl ß-D-1-thiogalactopyranoside (IPTG) were also evaluated as inducers for comparison of enzyme expression levels. The enzymatic extracts were purified by affinity chromatography, characterized, and applied in the bioconversion of D-galactose into D-tagatose. L-AI presented a catalytic activity of 1.67 ± 0.14, 1.52 ± 0.01, and 0.7 ± 0.04 U/mL, when expressed using commercial lactose, lactose from whey, and IPTG, respectively. Higher activities could be obtained by changing the protocol of enzyme extraction and, for instance, the enzymatic extract produced with whey presented a catalytic activity of 3.8 U/mL. The specific activity of the enzyme extracts produced using lactose (commercial or residual whey) after enzyme purification was also higher when compared to the enzyme expressed with IPTG. Best results were achieved when enzyme expression was conducted using 4 g/L of residual whey lactose for 11 h. These results proved the efficacy of an alternative and economic protocol for the effective expression of a recombinant L-AI aiming its high-scale production.