Xin Song
Shandong University, China
Title: Improvement of Penicillum oxalicum cellulase production via reconstruction of expression regulation network (RERN)
Biography
Biography: Xin Song
Abstract
Cellulolytic fungi Penicillium oxalicum produces diverse lignocellulolytic enzymes, and has been shown to be a promising cellulase producer. Given the dose-controlled or additive regulation of cellulase genes by the master regulator ClrB presented in P. oxalicum, and the synergistic transcriptional induction of cellulolytic genes in Bgl2-defi cient background, we constructed two overexpression cassettes gpdA(p)::clrB::ΔcreA-ptra and PDE_02864(p)::clrB::Δbgl2-bar, in which the clrB overexpression cassettes confer creA or bgl2 fl anking regions, respectively. Th ese overexpression cassettes for clrB were transformed sequentially into the pyrG mutant of P. oxalicum strain M12. Th e double mutant MRE1 (gpdA(p)::clrB::ΔcreA) and the quadruple mutant MRE2 (gpdA(p)::clrB::ΔcreAPDE_02864(p)::clrB::Δbgl2) were obtained, respectively and their cellulase expression abilities were separately evaluated on cellulose and wheat bran media. Although all these experiments were performed in fl asks, both MRE1 and MRE2 mutants showed more cellulolytic and xylanolytic enzyme activities and secretion abilities than parental strain M12. We also observed a signifi cant increase in the strain bearing the XlnRA871V allele (alanine-to-valine mutation) under cellulose conditions relative to the parental wild type strain
114-2. Th us, the overexpression cassette carrying PDE_02864-driven XlnRA871V using pyrG as selective marker was reconstructed and transformed into quadruple mutant MRE2, and might be feasible in further enhancing the cellulase expression. Th ese data signify that the dose-controlled regulation mechanisms of the cellulolytic regulators are a promising strategy for cellulolytic fungi to develop enzyme hyper-producers via the reconstruction of expression regulation network (RERN) technology.