Aleksandra M Rozhkova
Federal Research Centre “Fundamentals of Biotechnology-RAS, Russia
Title: Identify the causes of reduced productivity in industrial strains of the fungus Penicillium sp
Biography
Biography: Aleksandra M Rozhkova
Abstract
Penicillium verruculosum B-537- the cellulolytical fungal strain using as a host to obtain a number of recombinant strains demanded various biotechnology processes, in particular in feedstock refi nery. It has its own balanced complex of secreted cellulases, which are more eff ective in saccharifi cation of plant materials than similar complexes isolated from the fungus Trichoderma. Th e existence of expression and transformation systems for the P.verruculosum allows «tuning» of the secreted cellulase complex with heterologous genes to increase the effi ciency of plant raw material hydrolysis. However, analyzing the protein profi le in the culture fl uids of recombinant Penicillium verruculosum strains secreting Aspergillus niger β-glucosidase (BGL series) or Penicillium canescens xylanase A (XYLA series), two groups of strains were found: 1) producing strains with the content of the target protein up to 75-85% and 2) strains with the content of the target protein not more than 20%. Moreover, the fi rst group of strains was characterized by a decrease in the total productivity of the secreted protein by 1.5-2 times. Experiments to determine the copy number of target genes in recombinant strains showed a correlation between the β- glucosidase content in the BGL-F10 and BGL-F12 enzyme preparations and the number of copies of the bgl1 gene (80% and 20% β-glucosidase in BGL-F10 and BGL-F12 corresponded to 7-8 and 2 copies of the bgl1 gene). In the case of the xylA gene, the proportion was disrupted to reduce the relative content of xylanase A (50% and 17% xylanase A in the XylA3 and XylA4 enzyme preparations corresponded to 20 - 22 and 6 copies of the xylA gene). However, in both cases, overexpression of heterologous genes led to a decrease in the total productivity of the fungus to 25 g per 1L compared to 50 g per 1L in the case of the host strain. We explain eff ect of productivity reducing by titration of positive transcription factors in the XylA3 and BGL-F10 strains.