Recyclable immobilized Trichoderma reesei whole-cells for the catalytic oxidation of 5-hydroxymethylfurfural

Filamentous fungal whole-cells have recently demonstrated utility in oxidizing aldehyde substrate into carbox-ylic acid products. In this study, immobilization of filamentous fungal-whole cells was explored in the oxidation of 5-hydroxymethylfurfural into 5-hydroxymethyl-2-furan carboxylic acid (HMFCA). To that end, resting fila-mentous fungal whole-cells (Trichoderma reesei) were encapsulated in Ca-alginate beads to enable recyclability. It was found that encapsulation enabled the biocatalysts to be reliably recycled for up to nine reaction cycles. After 9 cycles, >290 mg of HMFCA was acquired at a molar yield of ~60%. By the tenth cycle, very little product was formed due to degradation of the immobilization matrix. Analysis of the biocatalysts via scanning electron microscopy revealed the formation of large pores while analysis via Fourier-transform infrared spectroscopy-attenuated total reflectance demonstrated depolymerization of the alginate matrix.