title: The influence of Aspergillus niger transcription factors AraR and XlnR in the gene expression during growth in D-xylose, L-arabinose and steam-exploded sugarcane bagasse.
abstract: The interest in the conversion of plant biomass to renewable fuels such as bioethanol has led to an increased investigation into the processes regulating biomass saccharification. The filamentous fungus Aspergillus niger is an important microorganism capable of producing a wide variety of plant biomass degrading enzymes. In A. niger the transcriptional activator XlnR and its close homolog, AraR, controls the main (hemi-)cellulolytic system responsible for plant polysaccharide degradation. Sugarcane is used worldwide as a feedstock for sugar and ethanol production, while the lignocellulosic residual bagasse can be used in different industrial applications, including ethanol production. The use of pentose sugars from hemicelluloses represents an opportunity to further increase production efficiencies. In the present study, we describe a global gene expression analysis of A. niger XlnR- and AraR-deficient mutant strains, grown on a D-xylose/L-arabinose monosaccharide mixture and steam-exploded sugarcane bagasse. Different gene sets of CAZy enzymes and sugar transporters were shown to be individually or dually regulated by XlnR and AraR, with XlnR appearing to be the major regulator on complex polysaccharides. Our study contributes to understanding of the complex regulatory mechanisms responsible for plant polysaccharide-degrading gene expression, and opens new possibilities for the engineering of fungi able to produce more efficient enzymatic cocktails to be used in biofuel production.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, S/N, CEP 14040-903, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Wagner Rodrigo
authors.initials: WR
authors.lastname: de Souza
authors.forename: Gabriela Piccolo
authors.initials: GP
authors.lastname: Maitan-Alfenas
authors.forename: Paula Fagundes
authors.initials: PF
authors.lastname: de Gouvêa
authors.forename: Neil Andrew
authors.initials: NA
authors.lastname: Brown
authors.forename: Marcela
authors.initials: M
authors.lastname: Savoldi
authors.forename: Evy
authors.initials: E
authors.lastname: Battaglia
authors.forename: Maria Helena S
authors.initials: MH
authors.lastname: Goldman
authors.forename: Ronald P
authors.initials: RP
authors.lastname: de Vries
authors.forename: Gustavo Henrique
authors.initials: GH
authors.lastname: Goldman
mesh_terms: D001089:Arabinose / Q000737:chemistry / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D056804:Biofuels; D018533:Biomass; D002482:Cellulose / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D011134:Polysaccharides / Q000378:metabolism; D031786:Saccharum / Q000382:microbiology; D015534:Trans-Activators / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D014157:Transcription Factors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D014994:Xylose / Q000737:chemistry / Q000378:metabolism*
chemical_list: D056804:Biofuels; D005656:Fungal Proteins; D011134:Polysaccharides; D015534:Trans-Activators; D014157:Transcription Factors; C115443:XlnR protein, Aspergillus; D000431:Ethanol; D002482:Cellulose; C027433:bagasse; D014994:Xylose; D001089:Arabinose
keywords: AraR; Aspergillus niger; Biofuels; Plant polysaccharide-degrading genes; Sugarcane bagasse saccharification; XlnR