title: The application of constitutively solvent-tolerant P. taiwanensis VLB120ΔCΔttgV for stereospecific epoxidation of toxic styrene alleviates carrier solvent use.
abstract: For whole-cell biotransformations involving toxic organic compounds, two-liquid phase setups are typically applied employing an apolar extractive phase. Bis(2-ethylhexyl)phthalate (BEHP) has proven to be an ideal solvent for stereospecific styrene epoxidation with recombinant E. coli, providing excellent extractive properties and a high biocompatibility. In eco-efficiency evaluations, BEHP, however, has been identified as a critical factor regarding costs and environmental impact. In this study, the constitutive solvent tolerance of Pseudomonas taiwanensis VLB120ΔCΔttgV is shown to enable high specific activities (up to 180 U gCDW-1) and extensive reduction of the BEHP amount in two-liquid phase setups and thus to constitute an excellent tool to improve the environmental and economic efficiency of such processes. At a 90% reduction of carrier solvent use and accordingly increased aqueous styrene concentrations, this strain still showed reasonably high specific styrene epoxidation activities (100 U gCDW-1), while the solvent-adaptable wildtype strain immediately was toxified. A moderate 55% reduction of BEHP enabled a specific activity of 150 U gCDW-1and thus represents a good trade-off between volumetric productivity maximization and environmental impact minimization. These results for the first time show a clear benefit of a solvent-tolerant compared to solvent-sensitive host strains and how such a benefit can be achieved.
authors.affiliation: Chair for Bioprocess engineering, Department of Biochemical and Chemical Engineering, TU Dortmund University, Dortmund, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Volmer
authors.affiliation: Department Solar Materials, Helmholtz Centre for Environmental Research GmbH - UFZ, Leipzig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schmid
authors.affiliation: Department Solar Materials, Helmholtz Centre for Environmental Research GmbH - UFZ, Leipzig, Germany.
authors.forename: Bruno
authors.initials: B
authors.lastname: Bühler
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D001711:Biotransformation; D004051:Diethylhexyl Phthalate / Q000737:chemistry; D004852:Epoxy Compounds / Q000378:metabolism*; D005818:Genetic Engineering; D011549:Pseudomonas / Q000235:genetics / Q000254:growth & development*; D012997:Solvents / Q000737:chemistry; D020058:Styrene / Q000378:metabolism*
chemical_list: D004852:Epoxy Compounds; D012997:Solvents; D020058:Styrene; D004051:Diethylhexyl Phthalate
keywords: Biochemical engineering; Pseudomonas; Solvent tolerance; Styrene epoxidation; Two-liquid phase biotransformation