Microplate MPN-enumeration of monocyclic- and dicyclic-aromatic hydrocarbon degraders via substrate phase-partitioning

Anders R. Johnsen, Sidsel Henriksen

Research output: Contribution to journalArticleResearchpeer-review

14 Citations (Scopus)


The high aqueous solubility of monoaromatic and some diaromatic oil components may hinder classical growth-based MPN enumeration of bacterial mono- and di-aromatics degraders because these aromatics are toxic in high concentrations. We developed a microplate MPN method for the enumeration of toluene-, xylene-, naphthalene-, biphenyl- and benzothiophene-degraders on the basis of phase-partitioning of substrate between a biologically inert organic phase and an aqueous mineral salt medium. This way, it was possible to maintain non-toxic, aqueous concentrations in the microplate wells. Depletion of aqueous aromatics by growth of the degraders was prevented by the continuous solubilization of aromatics from the silicone phase. The method was validated by MPN enumerating degrader cultures both with phase-partitioned aromatics and with tryptic soy broth as carbon sources. The applicability of the method was demonstrated by MPN-enumerating mono- and di-aromatic degraders in soils of varying hydrocarbon pre-exposure.

Original languageEnglish
Pages (from-to)581-589
Number of pages9
Issue number4
Publication statusPublished - Jul 2009


  • Benzothiophene
  • Biphenyl
  • MPN
  • Naphthalene
  • Toluene
  • Xylene

Programme Area

  • Programme Area 2: Water Resources


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