Project Background
Agricultural chemical treatments are widely used across Canada by farmworkers and aid in the production of competent crops. The popularity of organophosphate pesticides (OPPs) started peaking in the 1960s as a replacement for organochlorine insecticides [1]. OPPs were cheap and thought to degrade more quickly by hydrolysis on light and air exposure. However they did not fully degrade, as researchers still detected small amounts in drinking water, soils and food till today [2]. Inherently neurotoxic to humans, OPP exposure may occur through inhalation, ingestion, or dermal contact. For this reason, OPPs have been banned for home use in the U.S. and have attracted significant attention for their known harmful effects on the nervous system [3, 4].
Contaminated substances from industrial wastewater and manufacturers are disposed into nearby waters and agricultural runoffs where rainfall or irrigation watersheds pick up and carry away organophosphates (OPs) [5]. This is a pressing concern as OP compounds are powerful inhibitors of carboxylic ester hydrolysis, including acetylcholinesterase, which is found in human red blood cells, nerve cells, and skeletal muscles.
References
[1]Office of Medical and Scientific Justice. (2013, September 26). What are organophosphates? Office of Medical and Scientific Justice. Retrieved October 12, 2022, from https://www.omsj.org/blogs/deadly-organophosphates
[2]Organophosphate toxicity - statpearls - NCBI bookshelf. (n.d.). Retrieved October 12, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK470430/
[3]Overexposed || organophosphate insecticides in children's food. Environmental Working Group. (n.d.). Retrieved October 12, 2022, from https://www.ewg.org/research/overexposed-organophosphate-insecticides-childrens-food
[4]Says:, H. J. C. B., Buyer, H. J. C., & Series, W. (2022, March 12). Organophosphate pesticides. - Council for Environmental Research and Children's Health. Retrieved October 12, 2022, from https://cerch.org/uncategorized/organophosphate-pesticides/
[5] Z. J., Y. L., S. L., H. P., J. G., S. C. (2005, October 24). Treatment of Organophosphate- Contaminated wastewater by acidic hydrolysis and precipitation - NCBI (pubmed). Retrieved October 12, 2022.
Project Goals
The purpose of our bioremediation project CyanoClean is to use biological processes as an efficient and economic solution for the degradation of organophosphates. Our final goal is to sustainably implement CyanoClean in Canadian rural agricultural areas where pesticide usage and human exposure is high.
In order to accomplish this, our preliminary application will be the closed and controlled environment of the industrial water waste systems, since we will not be able to account for all the variables found in a rural wastewater system.
Since we want to implement our novel organism in the soil in the future, we designed a controlled cell death system that responds to the concentration of residual pesticides and their byproducts. This will ensure that any unforeseen effects of our genetically modified organism will be contained to avoid environmental damage.
We have also partnered with Warwick University to build a cell free sensor system to target the application of our technology.
To learn more about our application, click here.
Designing for sustainability
Our aim is to create a sustainable and economical way to carry out the degradation of organophosphate pesticides in Canada. In our project we tackle two OPP compounds: fenitrothion and malathion. We chose fenitrothion because of its toxicity to living ecosystems, and malathion because it is still in use in Canada. This is why we chose cyanobacteria as our chassis. It can metabolize different kinds of pesticides and it is mixotrophic, meaning it uses different nutrient sources for energy.
To learn more details about the cell free biosensor, click here.
For the degradation pathway, we have used the opH and opdB genes which can degrade 98-99% of multiple organophosphates.
To learn more details about the degradation pathway, click here.
The sepT2 and sepA2 genes are part of the toxin, sepT2 and antitoxin, sepA2, system. These genes encode for a RNA endonuclease and a __ respectively.
To learn more details about the toxin/antitoxin pathway, click here.
opH and opdB genes
We will develop a kill switch system in our cyanobacteria which will help control the technology and its spread into the environment. Previous studies demonstrated that pesticides can be expressed in cyanobacteria. To do so, our cyanobacteria model will use ammonium ions as a source of nitrogen and metabolize various organic substrates, including pesticides.
Killswitch Diagram:
