Biodegradation of biphenyl in a solid–liquid two-phase partitioning bioreactor

Biphenyl was successfully degraded by Burkholderia xenovorans LB400, initially described as Pseudomonas sp. LB400, in a solid–liquid wo-phase partitioning bioreactor (TPPB). Solid–liquid TPPBs are comprised of an aqueous, cell containing phase, and a solid polymeric phase hat partitions toxic and/or poorly soluble substrates (in this case biphenyl) based on maintaining a thermodynamic equilibrium. The employed olymer was HytrelTM, a thermoplastic polyester elastomer. The surface area available for mass transfer of biphenyl was limiting and resulted in ass transfer limited growth, as demonstrated experimentally by employing two different geometric shapes (cylinders with different aspect ratios) f the polymer phase with different specific surface area, while keeping all other parameters constant. The linear microbial growth rates were ubstantially higher when more polymer surface area was provided. The mass transfer coefficient of biphenyl from HytrelTM to water was measured under experimental conditions, which allowed predicting he release rate based on the biphenyl concentration gradient. The partitioning behaviour of biphenyl between HytrelTM and culture medium was easured as well, which allowed the development of a simple mechanistic model describing microbial growth based on known microbial properties n combination with substrate delivery from the solid polymer phase. The model was capable of describing the experimental data well and can e used to predict degradation rates for other geometric shapes of a solid delivery phase such as sheets or rods, which might be of operational dvantage in various applications of TPPBs to the controlled uptake and release of other recalcitrant molecules. 2007 Elsevier B.V. All rights reserved.