Optimization of high-molecular-weight polycyclic aromatic hydrocarbons' degradation in a two-liquid-phase bioreactor

J Appl Microbiol. 2000 Apr;88(4):655-62. doi: 10.1046/j.1365-2672.2000.01011.x.


A microbial consortium degrading the high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs) pyrene, chrysene, benzo[a]pyrene and perylene in a two-liquid-phase reactor was studied. The highest PAH-degrading activity was observed with silicone oil as the water-immiscible phase; 2,2,4,4,6,8, 8-heptamethylnonane, paraffin oil, hexadecane and corn oil were much less, or not efficient in improving PAH degradation by the consortium. Addition of surfactants (Triton X-100, Witconol SN70, Brij 35 and rhamnolipids) or Inipol EAP22 did not promote PAH biodegradation. Rhamnolipids had an inhibitory effect. Addition of salicylate, benzoate, 1-hydroxy-2-naphtoic acid or catechol did not increase the PAH-degrading activity of the consortium, but the addition of low-molecular-weight (LMW) PAHs such as naphthalene and phenanthrene did. In these conditions, the degradation rates were 27 mg l-1 d-1 for pyrene, 8.9 mg l-1 d-1 for chrysene, 1.8 mg l-1 d-1 for benzo[a]pyrene and 0.37 mg l-1 d-1 for perylene. Micro-organisms from the interface were slightly more effective in degrading PAHs than those from the aqueous phase.

MeSH terms

  • Benzo(a)pyrene / metabolism
  • Bioreactors*
  • Chrysenes / metabolism
  • Molecular Weight
  • Perylene / metabolism
  • Polycyclic Aromatic Hydrocarbons / metabolism*
  • Pyrenes / metabolism
  • Silicones


  • Chrysenes
  • Polycyclic Aromatic Hydrocarbons
  • Pyrenes
  • Silicones
  • Benzo(a)pyrene
  • Perylene