title: Experimental Evolution of Trichoderma citrinoviride for Faster Deconstruction of Cellulose.
abstract: Engineering faster cellulose deconstruction is difficult because it is a complex, cooperative, multi-enzyme process. Here we use experimental evolution to select for populations of Trichoderma citrinoviride that deconstruct up to five-fold more cellulose. Ten replicate populations of T. citrinoviride were selected for growth on filter paper by serial culture. After 125 periods of growth and transfer to fresh media, the filter paper deconstruction increased an average of 2.5 fold. Two populations were examined in more detail. The activity of the secreted cellulase mixtures increased more than two-fold relative to the ancestor and the largest increase was in the extracellular β-glucosidase activity. qPCR showed at least 16-fold more transcribed RNA for egl4 (endoglucanase IV gene), cbh1 (cellobiohydrolase I gene) and bgl1 (extracellular β-glucosidase I gene) in selected populations as compared to the ancestor, and earlier peak expressions of these genes. Deep sequencing shows that the regulatory strategies used to alter cellulase secretion differ in the two strains. The improvements in cellulose deconstruction come from earlier expression of all cellulases and increased relative amount of β-glucosidase, but with small increases in the total secreted protein and therefore little increase in metabolic cost.
authors.affiliation: The Biotechnology Institute, University of Minnesota, Twin Cities, Minnesota, United States of America.
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.affiliation: The Biotechnology Institute, University of Minnesota, Twin Cities, Minnesota, United States of America.|Department of Ecology Evolution and Behavior, University of Minnesota, Twin Cities, Minnesota, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Travisano
authors.affiliation: The Biotechnology Institute, University of Minnesota, Twin Cities, Minnesota, United States of America.|Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Twin Cities, Minnesota, United States of America.
authors.forename: Romas J
authors.initials: RJ
authors.lastname: Kazlauskas
mesh_terms: D002480:Cellulase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism*; D019020:Directed Molecular Evolution; D004790:Enzyme Induction; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D060847:Metabolic Engineering; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017423:Sequence Analysis, RNA; D014158:Transcription, Genetic; D014242:Trichoderma / Q000201:enzymology
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D002482:Cellulose; D002480:Cellulase
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