S-STEM
April 13, 2017
Project Background for the EMCC Student Conference
The Growth of Pseudomonas aeruginosa on Microplastics
Abstract:
In recent years, the Pseudomonas Aeruginosa bacteria have gained the attention of researchers looking to solve the plastic pollution in the world. The current research project for this semester is whether or not Pseudomonas Aeruginosa bacteria can be use to break down microplastics. Although finding a fast solution would be beneficial to the human population, research in this area is lacking because people believe plastic is cheap and easy to make. Manty are not concerned with the negative effects plastics have on the environment, In this studies, we use several sterilization and extraction methods examine Pseudomonas on the plastic. Seven types of recyclable plastics were collected and grinded into microplastics. Pseudomonas were placed on the plastic to see if colonies can digest the materials. The research will direct scientists to look further into finding techniques that safely lower the amount of microplastics in our environment.
Background Information:
The possibility of Pseudomonas aeruginosa bacteria growing on microplastics have become an important topic in the scientific community. Pseudomonas aeruginosa, bacteria that commonly grows in water and soil, thrives in urban and agricultural settings (Fujitani et al., 2010). Since the bacteria are aerobic, it dwells inside cooling towers, showers, irrigation systems, and medical devices. This is possible because the bacteria can produce a thick biofilm that helps it stay on damp surfaces (LaBauve and Wargo, 2012). Since the bacteria thrive in moist areas, humans often encounter the bacteria. In recent years, there have been signs that P. aeruginosa attaches itself to small microplastics, plastic particles smaller than 5 mm, that are found in the environment. Pseudomonas bacteria have high metabolic and stress resistance that helps it stick to plastics (Wierckx et al., 2015). Humans have increased plastic consumption in the last hundred years and that has cause more plastic waste to be found in local dump areas and local bodies of water. This is made possible by all oceans’ buoyancy and durability properties. In fact, the ability for plastics to travel far distance has led some researcher to call plastics hazardous materials (Eriksen, M. et al., 2014). Over the past 24 years, the North Atlantic Ocean have revealed a decrease in the size of the plastic particles (Wright, S. L., Thompson, R. C., & Galloway, T. S., 2013). Thus, there has been an increase in higher concentration of plastic items because of the smaller size. Large quantities of microplastics found in the ocean are from the poly-synthetic fibers used in athletic clothing (Galloway, 2015). Microplastics release harmful chemicals that leak out into the environment and disrupting wildlife (Alexander-White, 2016). If the bacteria can live on of tiny fragments of plastics found in moist areas near cities, then the bacteria will continuously encounter the human and animal population. If the proper conditions are met, P. aeruginosa will grow on which common microplastics found in urban waste? The hypothesis is that bacteria will grow on plastics, especially on the lesser dense plastics such as type 4 plastics found in plastic bags. The results may prove or this disproves this hypothesis
Learning more about this topic will enable scientists to evaluate the cost and benefits of having P. aeruginosa in the urban ecosystem. The bacteria pose threats because it is opportunistic pathogenic bacteria that can cause respiratory infections individuals with weakened immune systems such as individuals with cystic fibrosis (LaBauve and Wargo, 2012). The bacteria produce biofilm that allows it to stick to surfaces. Inside the biofilm are thousands of individual bacteria that sticks together in a matrix of protein particles. Biofilms are less likely to be killed off by a human’s inflammatory and immune responses (Vital-Lopez, F. G., Reifman, J., & Wallqvist, A., 2015). Studies have suggested that P. aeruginosa can eat through microplastics as well. If the bacteria can eat through plastics, then medical devices such as catheters and respiratory tubing may not be safe on humans with weak immune systems. This is one of the main concerns when it comes to use Pseudomonas bacteria to degrade plastics because many series of Pseudomonas are pathogenic (Wierckx et al., 2015). The bacteria can also play an important role in environmental measures. The world currently uses an estimate of 300 million tons of plastic annually (Galloway, 2015). Since plastics are often broken into smaller pieces because of UV radiation, chemical degradation, wave mechanics and grazing by marine life, the amount of plastic will continue to grow in size (Sebille, E. V et al., 2015). The buoyancy of the plastics allows the plastic to travel great distance and affect different ecosystems. Microplastic have been found in remote lakes across Mongolia (Mccormick, A et al., 2014). If the bacteria are proven to successfully eat plastic products, researchers can use the bacteria to decrease the amount of plastic that resides in landfills and other waste sites. Microplastics have been known to cause gut blockage, injuries, oxygen depletion, poor feeding habits, and loss of energy to animals that have digested it (Alexander-White, 2016). This prevent toxic, choking materials from encountering animals and humans. Research must be conducted in this area if humans want a prevention method to medical issues concerning P. aeruginosa or a solution to the growing plastic issues.
Hypothesis:
The current research topic is will Pseudomonas Aeruginosa grow on common microplastics found in urban waste? If so, can it degrade the plastics. The hypothesis is that bacteria will grow on eat through the lesser dense plastics such as type 2 and type 4 plastics found in plastic bags. The results that may prove or this disprove this hypothesis.
Variable:
Apparatus:
Procedure:
Recycle plastics were collected and identified.
Two sets of seven beakers were labeled one to seven so the corresponding plastic was placed in each beaker.
Microplastics were collected by grinding plastic using a grinding device into the corresponding beakers. For example, Type 1 plastics were placed in the breakers label with a number one.
One set of beakers were given UV sterilization for one hour.
The other set of beakers were given an alcohol sterilization by submerging the plastics overnight with 100% isopropyl solution. The plastics were dried by overhead fan of the UV machine or by heat if needed.
The plastics were transfer onto PF, PIA, and TSA plates and were incubated at 37 Celsius overnight.
Since 100% isopropyl solution appeared effective in sterilizing the microplastics versus the UV method, this method was chosen as the prefer method to sterilize plastics.
Any containment microplastics found during the sterilization process was given 42 Celsius test, Oxidase test, and a Gram stain test to identify if the unknown colony was Pseudomonas.
The sterilized microplastics were placed on another set of TSA plates with Pseudomonas to see if Pseudomonas will grow on it.
The amount of plastic on each TSA was measured before and after Pseudomonas grew on the TSA to see if the bacteria can eat through plastics.
Data:
Potential signs of Pseudomonas has been found on PIA, PF, and TSA plates that were given UV sterilized Type 2 plastics. These unknown colonies are undergoing identification process.
Analysis:
There is not sufficient data for a proper analysis. So far there are signs of Pseudomonas growing on Type 2 plastics but it is too early to say.
Conclusion: Claim
There is not sufficient data to provide a claim.
Conclusion: Evidence
There is not sufficient data to provide evidence.
Conclusion: Reasoning
There is not sufficient data to provide reasoning.
Conclusion: Merit
There is not sufficient data to provide merit.
Reference:
Alexander-White, C. (2016, November 15). The massive problem of microplastics. Retrieved February 23, 2017, from https://eic.rsc.org/feature/the-massive-problem-of-microplastics/2000127.article
Galloway TS, 2015. Micro- and Nano-plastics and Human Health. In: Bergmann M, Gutow L and Klages M (eds). Marine anthropogenic litter. Springer International Publishing, Cham. pp. 343–366. http://biosciences.exeter.ac.uk/documents/Micro-and_Nano-plastics_and_Human_Health_Galloway.pdf
LaBauve, A. E., & Wargo, M. J. (2012). Growth and Laboratory Maintenance of Pseudomonas aeruginosa. Current Protocols in Microbiology, 0 6, Unit–6E.1. http://doi.org/10.1002/9780471729259.mc06e01s25
Wierckx, N., Prieto, M. A., Pomposiello, P., de Lorenzo, V., O’Connor, K., & Blank, L. M. (2015). Plastic waste as a novel substrate for industrial biotechnology. Microbial Biotechnology, 8(6), 900–903. http://doi.org/10.1111/1751-7915.12312
Fujitani, S., M.D. (2010, January 1). Pseudomonas aeruginosa. Retrieved February 23, 2017, from http://www.antimicrobe.org/new/b112.asp
Wright, S. L., Thompson, R. C., & Galloway, T. S. (2013). The physical impacts of microplastics on marine organisms: A review. Environmental Pollution, 178, 483-492. doi:10.1016/j.envpol.2013.02.031
Eriksen, M. et al., (2014). Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. PLoS ONE, 9(12). doi:10.1371/journal.pone.0111913
Sebille, E. V et al., (2015). A global inventory of small floating plastic debris. Environmental Research Letters, 10(12), 124006. doi:10.1088/1748-9326/10/12/124006
Mccormick, A., Hoellein, T. J., Mason, S. A., Schluep, J., & Kelly, J. J. (2014). Microplastic is an Abundant and Distinct Microbial Habitat in an Urban River. Environmental Science & Technology, 48(20), 11863-11871. doi:10.1021/es503610r
Vital-Lopez, F. G., Reifman, J., & Wallqvist, A. (2015). Biofilm Formation Mechanisms of Pseudomonas aeruginosa Predicted via Genome-Scale Kinetic Models of Bacterial Metabolism. PLOS Computational Biology, 11(10). doi:10.1371/journal.pcbi.1004452
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