This year, the University of Calgary iGEM team aims to build a biosensor for naphthenic acids (NAs). NAs are organic acids that are toxic to terrestrial and aquatic wildlife. Because they are waste products of the bitumen extraction process that mines petroleum from the Alberta oil sands, the accumulation of NAs in the on-site settling ponds (tailings ponds) is an environmental concern requiring constant monitoring and eventual remediation. In addition to harming the environment, NAs also contribute to refinery equipment corrosion, directly increasing maintenance and replacement costs. Currently, sophisticated and expensive procedures, such as Fourier Transform Infrared Spectrometer (FTIR) or gas chromatography-mass spectrometry, are needed to identify and assess NA concentrations in the environment. A bacterial sensor, if developed, could greatly improve the cost- and time-efficiency of NA detection, and facilitate a workable approach for remediation.

Our Naphthenic Acid Biosensor

A detailed description of our project can be seen here! Below is a picture of what our final product will look like. We will have our biosensing bacterium in a container that the sample to be measured can be added to.

Roll over the bacterium below!

An NA-Sensitive Promoter

The most critical component of our biosensor is a naphthenic acid sensory element. This would likely be a promoter element. The major challenge for this was that given the lack of available information on NA degradation, there was no NA sensitive promoter available in the literature for us to use. We needed to develop methods to search for such an element. These included our novel “fishing” method as well as our bioinformatics approach. Click on the promoter to learn more about this!

An Electrochemical Reporter

We need a reliable reporter for our system. Given the highly variable and often turbid nature of oil sands tailings ponds however, we needed a special kind of reporter. We chose to use the lacZ gene, but characterize it as an electrochemical reporter. Click the gene to learn more!

A Suitable Chassis

We need a chassis in which to house our system. Given that we intended to get our sensory element from either Pseudomonas or microalgae, and that these organisms are both naturally present within tailings ponds, we chose to focus on them. As such, we contributed and characterized several parts for future work in microalgae, and to move plasmids efficiently from E. coli to Pseudomonas. Click the chassis to learn more!