title: Measuring mass transfer processes of octane with the help of an alkSalkB::gfp-tagged Escherichia coli.
abstract: Diffusion of octane from oily droplets in different microscale settings was measured using Escherichia coli expressing the stable green fluorescent protein (GFP) from the alkB promoter of Pseudomonas oleovorans. GFP fluorescence intensities were determined quantitatively at the single-cell level after 1.0 or 2.5 h incubation and compared with different calibration series using known concentrations of octane. By immobilizing the E. coli sensor cells on the bottom glass plate of a microscope flow chamber, it was possible to monitor the diffusion process for octane in aqueous solution as a function of time and distance from non-aqueous phase droplets of octane alone or oily octane mixtures. When a gas phase was included in the flow chambers, octane transport could be demonstrated from the oily mixtures to the cells through both gas and liquid phase. Assays of non-immobilized sensor cells in microdroplets in the presence or absence of soil particles incubated with octane through the vapour phase revealed a slight reduction in the total amount of induced E. coli cells in the presence of soil. Our results indicate the power of using GFP-marked single-cell biosensors in determining microscale bioavailability of organic pollutants.
authors.affiliation: Swiss Federal Institute for Environmental Science and Technology (EAWAG), Postfach 611, Uberlandstrasse 133, CH 8600 Dübendorf, Switzerland.
authors.forename: M C
authors.initials: MC
authors.lastname: Jaspers
authors.forename: C
authors.initials: C
authors.lastname: Meier
authors.forename: A J
authors.initials: AJ
authors.lastname: Zehnder
authors.forename: H
authors.initials: H
authors.lastname: Harms
authors.forename: J R
authors.initials: JR
authors.lastname: van der Meer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001673:Biodegradation, Environmental; D015374:Biosensing Techniques; D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004058:Diffusion; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005740:Gases / Q000378:metabolism; D005818:Genetic Engineering; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009795:Octanes / Q000378:metabolism* / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011549:Pseudomonas / Q000235:genetics; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005740:Gases; D008164:Luminescent Proteins; D009795:Octanes; D012989:Soil Pollutants; D014157:Transcription Factors; D014867:Water; D049452:Green Fluorescent Proteins; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D042926:Cytochrome P-450 CYP4A; C026728:octane