Would the pathogen sensor have a false positive problem?
Possible. The gut flora has been shown to contain AI-3. Normally, enterohaemorrhagic E.coli would produce AI-2, and hence AI-3, but some strains like DH5α doesn’t, which may indicate that AI-3 production is increased in pathogenic strains. This allows the sensor to be more specific.
How does our solution compare to current alternatives?
Disinfectants
Disinfectants are chemicals applied to inanimate surfaces to rapidly kill or inactivate microorganisms and sometimes spores. They generally disrupt membrane function and/or interfere with nucleic acids or cytoplasmic components of biological targets, and typically involve multiple target sites1.
Common traditional disinfectants used in farms include sodium hypochlorite (household bleach), acids (5% acetic acids), bases (e.g. 2% sodium hydroxide, soda ash), phenol-based compounds (e.g. 1-Stroke Environ) and Virkon™ S, which is a combination of peroxygen molecules, organic acids and surfactants. Some (e.g. chlorine compounds, Virkon™ S) have a broad spectrum of activity against bacteria and viruses, but others are only effective on specific organisms under certain conditions (for example, quaternary ammonium compounds are not effective against M. paratuberculosis, the cause of Johne’s disease).2
The new generation of disinfectants use hydrogen peroxide as an active ingredient. They are highly effective against a broad spectrum of microorganisms including fungi, bacteria and viruses. Their by-products are non-toxic. Some are even made to food safe standards3.
Just as our biofilm, disinfectants are only effective on a cleaned surface. All of the types of disinfectants mentioned, except for phenol-based ones, are deactivated by organic materials.
However, even the best disinfectants could only make the surface clean for the moment. Bacteria can quickly come back once debris builds up. Additionally, some surfaces are difficult to clean. Those surfaces might still have dirty materials or biofilms on it, making disinfectants ineffective.
Spraying a protective biofilm after disinfecting would be a good solution to maintain a low pathogen count on surfaces that would be dirty in the future. By occupying the surface in advance, pathogenic biofilms cannot grow so there is less chance of leaving pathogenic biofilm at the corner.
Antimicrobial paints
Antimicrobial paints are permanent chemical coverings for surfaces such as walls and floors that have antimicrobial properties. They sound exactly like what an ultimate solution to pathogen growth on surfaces should be. Let’s first take a closer look at what they are made of and what makes them antimicrobial.
A paint generally consists of pigments, a binder that connects different ingredients, and a solvent that gives the paint a liquid state. On top of these, paints usually have ingredients that confer extra properties.
Antimicrobial paints can be classified into the following types4:
1. Contains eluting agents such as antibiotics, nanoparticles or ions that will be released to kill bacteria
2. Contains contact active immobilised molecules such as chitosan/quaternary ammonium polymers or antimicrobial peptides - contact killing or anti-adhesive
3. Contains light activated molecules such as TiO2 and photosensitisers. - absorbs photon and create free radicals to kill bacteria
Efficacy of antimicrobial paints are reported to be reasonably good. A study on the efficacy of antimicrobial paints in hospital ICU that involved seven copper containing antimicrobial paint showed a modest (58%) reduction of healthcare-associated infection and 64% reduction in transmission of antimicrobial resistant organisms5.
However, there is a risk of developing antimicrobial resistance by evolution through de-novo mutation and horizontal transfer, and species sorting of inherently resistant bacteria dispersed onto antimicrobial surfaces6. This is true for paints that contain metal such as copper and silver7 and antimicrobial peptides. Therefore, it is not clear how long the antimicrobial paints can stay effective.
A biofilm solution is unique in that it does not release any toxin that imposes a selection pressure related to existing antimicrobials, so it will not contribute to the development of antimicrobial resistance.
Non-GM probiotics
There are examples of commercially available positive biofilms to protect surfaces using a combination of wild-type bacteria8. Data showed that these biofilms have an issue with surface coverage9. Therefore, we are trying to create a faster/stronger biofilm-forming bacteria by genetic engineering.
Reference
1. Wales, A. D., Gosling, R. J., Bare, H. L., & Davies, R. H. (2021). Disinfectant testing for veterinary and agricultural applications: A review. Zoonoses and Public Health, 68(5), 361–375.
2. Disinfection in On-Farm Biosecurity Procedures. (n.d.). Retrieved from https://ohioline.osu.edu/factsheet/vme-8
3. Disinfection in Livestock Farming - Oxyl-Pro. (2021, October 14). Retrieved from https://www.oxylpro.com/disinfection-in-livestock-farming/#:~:text=Oxyl%2DPro%20is%20also%20highly,in%20contact%20with%20most%20metals.
4. Gupta, S., Puttaiahgowda, Y. M., Nagaraja, A., & Jalageri, M. D. (2021). Antimicrobial polymeric paints: An up‐to‐date review. Polymers for Advanced Technologies, 32(12), 4642–4662.
5. Muller, M. P., MacDougall, C., Lim, M., … Vearncombe, M. (2016). Antimicrobial surfaces to prevent healthcare-associated infections: a systematic review. Journal of Hospital Infection, 92(1), 7–13.
In-Text Citation: (Muller et al. 2016)
6. Pietsch, F., O’Neill, A. J., Ivask, A., … Schreiber, F. (2020). Selection of resistance by antimicrobial coatings in the healthcare setting. Journal of Hospital Infection, 106(1), 115–125.
7. Pal, C., Asiani, K., Arya, S., … Hobman, J. L. (2017, January 1). Metal Resistance and Its Association With Antibiotic Resistance. doi:10.1016/bs.ampbs.2017.02.001
8. Yeast and bacteria probiotics | Lallemand Animal Nutrition. (2023, June 13). Retrieved from https://lallemandanimalnutrition.com/en/europe/products/in-feed-solutions/yeast-and-bacteria-probiotics/
9. Guéneau, V., Rodiles, A., Frayssinet, B., … Briandet, R. (2022). Positive biofilms to control surface-associated microbial communities in a broiler chicken production system - a field study. Frontiers in Microbiology, 13. published. doi:10.3389/fmicb.2022.981747