Improved cellulolytic efficacy in Penicilium decumbens via heterologous expression of Hypocrea jecorina endoglucanase II

Hypocrea jecorina endoglucanase II (Hjegl2) was heterologously expressed in Penicillium decumbens (yielding strain Pd::Hjegl2). After induction in cellulose containing media, strain Pd::Hjeg2 displayed increased carboxymethylcellulase activity (CMCase, 5.77 IU/ml, representing a 21% increase) and cellulose degradation determined with a filter paper assay (FPA, 0.40 IU/ml, 67% increase), as compared to the parent strain. In media supplemented with glucose (2%), Pd::Hjegl2, displayed 51.2-fold and 3-fold higher CMCase and FPA activities, respectively, as compared to the parent strain. No changes in the expression levels of the four main native cellulase genes of P. decumbens (Pdegl1, Pdegl2, Pdcbh1, and Pdcbh2) were noted between the transformant and wild-type strains. These data support the idea that Hjegl2 cleaves both internal and terminal glycosidic residues, in a relatively random and processive manner. In situ polyacrylamide gelactivity staining of extracts derived from wild-type and Pd::Hjegl2 revealed two additional active fractions in the latter strain; one with a molecular mass ~50-65 KDa and another ~80-116 kDa.