Expression and characterization of a family 45 glycosyl hydrolase from Fomitopsis pinicola and comparison to Phanerochaete chrysosporium Cel45A

To efficiently decompose biomass, fungi have developed various enzymatic and non-enzymatic strategies and are a source of versatile biocatalysts. The endoglucanases in glycosyl hydrolase CAZy family 45 (GH45) are known for their small size, a high thermostability and a broad substrate specificity that has been employed in textile and detergent industries. Here we report the heterologous expression and characterisation of an GH45 endoglucanase from the brown rot Fomitopsis pinicola and its direct comparison to an already characterised GH45 from the white rot Phanerochaete chrysosporium. Both enzymes were recombinantly expressed in Pichia pastoris and purified by two chromatographic steps. The biochemical characterisation highlighted the acidophilic character, with an optimal pH of 4, and a preference for amorphous substrates as carboxymethyl cellulose (CMC) and substrates containing beta-1,4-glucans rather than the previously reported beta-1,3/1,4-glucans lichenan and beta-glucan. The dominating products from beta-1,4-glucans were C3-C6 oligosaccharides, whereas from beta-1,3/1,4-glucans glucose was the main reaction product. From the characterisation no differences between the brown rot and the white rot GH45 was evident.

Automated summary

Fungi efficiently decompose biomass using enzymatic and non-enzymatic strategies, and they are a valuable source of versatile biocatalysts. This study compared the characteristics of GH45 endoglucanases from the brown rot Fomitopsis pinicola and the white rot Phanerochaete chrysosporium, and found no significant differences between them.