title: Antimicrobial activity of filamentous fungi isolated from highly antibiotic-contaminated river sediment.
abstract: BACKGROUND
  Filamentous fungi are well known for their production of substances with antimicrobial activities, several of which have formed the basis for the development of new clinically important antimicrobial agents. Recently, environments polluted with extraordinarily high levels of antibiotics have been documented, leading to strong selection pressure on local sentinel bacterial communities. In such microbial ecosystems, where multidrug-resistant bacteria are likely to thrive, it is possible that certain fungal antibiotics have become less efficient, thus encouraging alternative strategies for fungi to compete with bacteria.
  
  
  METHODS
  In this study, sediment of a highly antibiotic-contaminated Indian river was sampled in order to investigate the presence of cultivable filamentous fungi and their ability to produce substances with antimicrobial activity.
  
  
  RESULTS
  Sixty one strains of filamentous fungi, predominantly various Aspergillus spp. were identified. The majority of the Aspergillus strains displayed antimicrobial activity against methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase-producing Escherichia coli, vancomycin-resistant Enterococcus faecalis and Candida albicans. Bioassay-guided isolation of the secondary metabolites of A. fumigatus led to the identification of gliotoxin.
  
  
  CONCLUSIONS
  This study demonstrated proof of principle of using bioassay-guided isolation for finding bioactive molecules.
authors.affiliation: Department of Medicinal Chemistry, Division of Pharmacognosy, Uppsala University, Uppsala, Sweden.
authors.forename: K Stefan
authors.initials: KS
authors.lastname: Svahn
authors.forename: Ulf
authors.initials: U
authors.lastname: Göransson
authors.forename: Hesham
authors.initials: H
authors.lastname: El-Seedi
authors.forename: Lars
authors.initials: L
authors.lastname: Bohlin
authors.forename: D G Joakim
authors.initials: DG
authors.lastname: Larsson
authors.forename: Björn
authors.initials: B
authors.lastname: Olsen
authors.forename: Erja
authors.initials: E
authors.lastname: Chryssanthou