Bacterial bioreporters and pollutant effects

Bacterial bioreporters | Pollutant effects

Bacterial bioreporters

Whole cell bacterial bioreporters are bacteria specifically engineered to react to the presence of chemical signals with the production of an easily quantifiable marker protein. In most cases, an existing regulatory system in the bacterial cell is exploited to drive expression of a specific reporter gene, such as bacterial luciferase, green fluorescent protein, beta-galactosidase or others. This is achieved by fusing the DNA for a promoterless reporter gene to an extra copy of the selected regulatable promoter and introducing this construction into the bacterial cell. Regulatory systems that have been applied include those for heavy metal resistancies (to obtain heavy metal responsive sensors), for organic compound degradation (to obtain organic compound sensors), and for cellular stress responses (to obtain general toxicity sensors).

Most whole-cell bacterial bioreporters are applied by incubating the cells in aqueous solution with the target compound(s) and analyzing the activity of the reporter protein (i.e., the reporter signal) after a previously calibrated induction period. Concentrations of the target chemical in unknown samples are inferred by comparing the reporter signal to that with a series of standard concentrations and incubated under exactly the same conditions. The reporter signal is usually only proportional to the target chemical within a specific concentration range. At higher target concentrations, the sensor output becomes saturated or even diminishes because of toxic effects to the sensor cells.

Current projects focus on application of bioreporter protocols for measurement in urine, on automizing bioreporters in microfluidic systems and reactors, and on expanding the range of compounds that is currently detected. Hereto we study periplasmic binding proteins and chemotaxis.

Pollutant effects

Within the framework of a new collaborative project MicroScapes, we are investigating the usefulness of applying specific bacterial strains to remediate toxic compounds. With the help of transcriptomic and genetic studies we are trying to unravel which stress pathways become activated when such bacteria are re-implanted in a contaminated environment, and how this affects their capability to degrade the target chemicals. We are also developing new tools to study in high throughput the possible interactions between introduced and the resident bacteria in the soil.

In another project we are trying to understand the effects that pollutants and low concentrations may have on aquatic microbial communities. We are interested to study how we can detect growth of bacteria at very low pollutant concentrations using flow cytometry and ultra high throughput microcultivation plates.

Finally, in a set of collaborative projects with Antoine Guisan from the Department of Ecology and Evolution, we are studying microbial diversity in Alpine grasslands in order to understand how microbial diversity influences plant diversity, and how changing climate may influence microbial diversity.

Bacterial biosensors to measure arsenic in potable water....>>

FACEiT: Research project supported by the Sixth EU Framework Programme....>>

BIOMONAR: Development of new aquatic sensors ...>>


Arsenic reporter cells embedded in agarose microbeads within a microfluidics cage. Picture: Nina Buffi, EPFL.

Alkane-responsive bacterial biosensors respond to the presence of octane by producing bioluminescence.


Subsection of a 20 µm well ultrahigh throughput cultivation disk. 

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