Quorum sensing activity in Ophiostoma ulmi: Effects of fusel oils and branched chain amino acids on yeast-mycelial dimorphism

A. Berrocal, J. Navarrete, C. Oviedo, K. W. Nickerson

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Aims: For Ophiostoma (Ceratocystis) ulmi, the ability to undergo morphological change is a crucial factor for its virulence. To gain an understanding of quorum-sensing activity in O. ulmi as it relates to yeast-mycelium dimorphism control, this study examines the effects of branched-chain amino acids as well as their fusel alcohols and fusel acids as quorum sensing molecules. Methods and Results: In a defined medium containing glucose, proline and salts, O. ulmi grew as yeasts when the culture was inoculated with a high density of spores (2×107CFUml-1) and as mycelia when inoculated with a low spore density (4×105CFUml-1). The cultures displaying yeast morphology secreted a quorum-sensing factor that shifted the morphology from mycelia to yeast. This quorum-sensing molecule was lipophilic and extractable by organic solvents from the spent medium. Using GC/MS analysis, it was determined that the major compound in the extract was 2-methyl-1-butanol. A similar effect was observed when the branched-chain amino acids (fusel alcohol precursors) were used as the nitrogen source. E, E-farnesol had no effect on the morphology of O. ulmi. Conclusions: Addition of the branched-chain amino acids or one of the compounds detected in the spent medium, 2-methyl-1-butanol or 4-hydroxyphenylacetic acid, or methylvaleric acid, decreased germ tube formation by more than 50%, thus demonstrating a quorum sensing molecule behaviour in O. ulmi cultures. Significance and impact of the study: This study presents advances in the investigation of dimorphism in O. ulmi, complementing the existing scientific basis, for studying, understanding and controlling this phenomenon.

Original languageEnglish (US)
Pages (from-to)126-134
Number of pages9
JournalJournal of Applied Microbiology
Issue number1
StatePublished - Jul 2012
Externally publishedYes


  • Aromatic alcohols
  • Branched-chain amino acids
  • Fungal dimorphism
  • Inoculum size
  • Ophiostoma ulmi
  • Quorum sensing activity

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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