title: Transcriptomic and metabolomic profiling of ionic liquid stimuli unveils enhanced secondary metabolism in Aspergillus nidulans.
abstract: BACKGROUND
  The inherent potential of filamentous fungi, especially of Ascomycota, for producing diverse bioactive metabolites remains largely silent under standard laboratory culture conditions. Innumerable strategies have been described to trigger their production, one of the simplest being manipulation of the growth media composition. Supplementing media with ionic liquids surprisingly enhanced the diversity of extracellular metabolites generated by penicillia. This finding led us to evaluate the impact of ionic liquids' stimuli on the fungal metabolism in Aspergillus nidulans and how it reflects on the biosynthesis of secondary metabolites (SMs).
  
  
  RESULTS
  Whole transcriptional profiling showed that exposure to 0.7 M cholinium chloride or 1-ethyl-3-methylimidazolium chloride dramatically affected expression of genes encoding both primary and secondary metabolism. Both ionic liquids apparently induced stress responses and detoxification mechanisms but response profiles to each stimulus were unique. Primary metabolism was up-regulated by choline, but down-regulated by 1-ethyl-3-methylimidazolium chloride; both stimulated production of acetyl-CoA (key precursor to numerous SMs) and non proteinogenic amino acids (building blocks of bioactive classes of SMs). In total, twenty one of the sixty six described backbone genes underwent up-regulation. Accordingly, differential analysis of the fungal metabolome showed that supplementing growth media with ionic liquids resulted in ca. 40 differentially accumulated ion masses compared to control conditions. In particular, it stimulated production of monodictyphenone and orsellinic acid, otherwise cryptic. Expression levels of genes encoding corresponding polyketide biosynthetic enzymes (i.e. backbone genes) increased compared to control conditions. The corresponding metabolite extracts showed increased cell polarity modulation potential in an ex vivo whole tissue assay (The lial Live Targeted Epithelia; theLiTE™).
  
  
  CONCLUSIONS
  Ionic liquids, a diverse class of chemicals composed solely of ions, can provide an unexpected means to further resolve the diversity of natural compounds, guiding discovery of fungal metabolites with clinical potential.
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
authors.forename: Paula C
authors.initials: PC
authors.lastname: Alves
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
authors.forename: Diego O
authors.initials: DO
authors.lastname: Hartmann
authors.affiliation: Department of Analytical Chemistry, University of Barcelona, Diagonal 645, E-08028, Barcelona, Spain.|Serra Hunter Fellow, Generalitat de Catalunya, Barcelona, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Núñez
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Martins
authors.affiliation: Thelial Technologies S.A., Parque Tecnológico de Cantanhede, Nucleo 04 Lote 3, 3060-197, Cantanhede, Portugal.
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Gomes
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
authors.forename: Helga
authors.initials: H
authors.lastname: Garcia
authors.affiliation: Department of Analytical Chemistry, University of Barcelona, Diagonal 645, E-08028, Barcelona, Spain.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Galceran
authors.affiliation: Thelial Technologies S.A., Parque Tecnológico de Cantanhede, Nucleo 04 Lote 3, 3060-197, Cantanhede, Portugal.
authors.forename: Richard
authors.initials: R
authors.lastname: Hampson
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156, Oeiras, Portugal.
authors.forename: Jörg D
authors.initials: JD
authors.lastname: Becker
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal. spereira@itqb.unl.pt.
authors.forename: Cristina
authors.initials: C
authors.lastname: Silva Pereira
mesh_terms: D000818:Animals; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D004330:Drosophila; D005260:Female; D052578:Ionic Liquids / Q000737:chemistry*; D055442:Metabolome; D020411:Oligonucleotide Array Sequence Analysis; D064210:Secondary Metabolism; D013312:Stress, Physiological; D059467:Transcriptome
chemical_list: D052578:Ionic Liquids
keywords: Aspergillus nidulans; Ionic liquids; Metabolomics; Monodictyphenone; Orsellinic acid; Secondary metabolism; Transcriptomics