Biosynthesis of hyaluronan in engineered Escherichia coli via the secretion of thermophilic exo-mannanase using palm kernel cake as the carbon source

Abstract

The potential of palm kernel cake (PKC) wastes as feedstocks for the production of hyaluronic acid (HA) using engineered Escherichia coli has been investigated. Herein, we report a novel thermophilic exo-β-D-mannanase TFMS, which exhibits superior enzymatic properties and more efficiently hydrolyzes PKC to yield oligosaccharides composed of 1-m to 10-m monosaccharide residues. By optimizing signal peptides, we achieved high-level secretory production of TFMS in engineered chassis strain, which could effectively release oligosaccharides from PKC for cell growth. Our results confirm that the chassis strain maintains relatively high cell-growth rates and biomass in PKC media with approximately 70.5% levels of that in LB media. Furthermore, hasA, a HA synthase gene from Streptococcus zooepidemicus, was expressed in chassis strain to produce a relatively high HA accumulation of 192 mg/L from PKC. This study provides a new approach for developing feedstock utilizations of PKC wastes by constructing efficient microbial cell factories to biosynthesize value-added products.