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Updated: Jun 27, 2026

Isolation, Propagation, and Identification of Bacterial Species with Hydrocarbon Metabolizing Properties from Aquatic Habitats
Published on: December 7, 2021
Microplate MPN-enumeration of monocyclic- and dicyclic-aromatic hydrocarbon degraders via substrate
Anders R Johnsen1, Sidsel Henriksen
1Department of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen K, Denmark. arj@geus.dk
Abstract:
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.
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