Generation of recombinants strains to cellulases production by protoplast fusion between Penicillium echinulatum and Trichoderma harzianum
Nowadays, cellulase importance is growing mainly due to its potential utilization in developing second-generation ethanol technology. Thus, considerable effort has been made to obtain new genotypes with improved capacity to produce efficient and cost-effective enzyme complexes for cellulose hydrolysis. The majority of the genetically manipulated strains that produce higher amounts of cellulases come from of the wild Trichoderma reesei QM6A. Such as T. reesei cellulolytic mutants, Penicillium echinulatum mutants also produce high titles of cellulases (filter paper activities—FPA), and its enzymatic complex effectively hydrolyses cellulose. In the present work, we obtained genetic variability with the purpose of enhancing cellulase production by protoplast fusion between P. echinulatum and T. harzianum. The resulting fusants, who were all morphologically like the P. echinulatum parental, were initially characterized by RAPD, and the results showed that almost all amplified DNA bands showed correlation with P. echinulatum DNA bands. Some of new selected strains presented higher FPA and β-glucosidases activities when compared to the parental strains. One particular clone – BP2 – showed values of FPA activities around of 2 UI ml−1, in submerged cultures and all selected strains showed faster and higher secretion of cellulases in solid-state cultures, in comparison to the parental strain of P. echinulatum. Altogether, at the same time that our results show increased cellulase secretion by P. echinulatum strains, they also show that protoplast fusion techniques associated with an efficient selection process could be a useful tool in genetic improvement to generate better cellulose-producing strains aimed at economically hydrolyzing cellulose with a view to second-generation ethanol.
Journal: Enzyme and Microbial Technology - Volume 43, Issue 6, 6 November 2008, Pages 403–409