Biodegradation of 2,4,5-trichlorophenol by aerobic microbial communities: Biorecalcitrance, inhibition, and adaptation

Michael D. Marsolek, Mary Jo Kirisits, Bruce Rittmann

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Chlorinated aromatic compounds challenge our environment and wastewater treatment processes due to their biorecalcitrance and inhibition. In particular, 2,4,5-trichlorophenol (TCP) seems to demonstrate greater resistance to biodegradation than other trichlorophenols and is a known uncoupler of the electron transport chain, although little work addresses this compound specifically. Here, we investigate the biorecalcitrance, inhibition, and adaptation to 2,4,5-trichlorophenol by aerobic mixed microbial communities. We show that 2,4,5-trichlorophenol is strongly resistant to biodegradation at concentrations greater than 40 μM, demonstrates inhibition to respiration in direct proportion to 2,4,5-trichlorophenol concentration (with 50% inhibition projected near 85 μM 2,4,5-trichlorophenol), and does not sustain biomass in continuous reactors, even when all input 2,4,5-trichlorophenol is degraded. Communities showed consistent adaptation patterns to 2,4,5-trichlorophenol at concentrations of 10 μM and 20 μM, but these patterns diverged at concentrations greater than 40 μM. Finally, thermodynamic approximations were used to estimate the yield of 2,4,5-trichlorophenol as 0.165 gVSS/gCOD, a low value that partially explains why biodegradation of 2,4,5-trichlorophenol did not sustain the biomass. In particular, we estimated that the minimum concentration to support steady-state biomass (Smin) is approximately 180 μM, a value much larger than the 40-μM concentration that is strongly resistant to biodegradation. Thus, readily biodegradable concentrations of 2,4,5-trichlorophenol are too low to sustain the biomass that biodegrades it.

Original languageEnglish (US)
Pages (from-to)351-358
Number of pages8
Issue number3
StatePublished - Jun 2007


  • 2,4,5-trichlorophenol
  • Adaptation
  • Biodegradation
  • Inhibition
  • Recalcitrance

ASJC Scopus subject areas

  • Environmental Engineering
  • Microbiology
  • Bioengineering
  • Environmental Chemistry
  • Pollution


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