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YPIE Scientist: Abigail Gutierrez

Research: Microplastic Digestion: The Impact of Soil pH on the Rate of Digestion of Microplastic by Rhodococcus ruber

Mentor: Angela Brown

Awards: Somers Science Fair - Participant 2023

Research Location: Westchester- Tarrytown, Ossining and Yonkers, New York


Landfills are filling rapidly with plastic, as 91% of plastic produced is not being recycled. There are about over 335 million tons of plastic produced annually globally, and 35.7 million tons in the United States. Microplastics are plastic particles smaller than 5 mm. Rhodococci are known for displaying a wide metabolic versatility and for their ability to transform a varied range of pollutants. The study was conducted in Yonkers, Tarrytown and Ossining in Westchester County, New York. Microplastic was made by blending plastic water bottles and evenly distributed into five sets of five different soil pH’s that were inoculated with Rhodococcus ruber. The samples were left alone for 5 months (May-September) and biweekly observations were taken on them. Soil was dehydrated, microplastic was filtered out using a floatation method with oil and water, then put in a Kl solution and centrifuged. The supernatant was removed and the microplastic was put on filter paper that was stained by Nile Red dye and quantified using the smartphone connected microscope. During the observations it was noted that there was no big change in the physical properties. There was no Rhodococcus growth and the microplastic looked the same. That was until the final month where the soil pH sets of 7 and 9 had mold-like growth all around the soil. It was found that each soil sample had at least 75% digestion rate and the soil pH of 7 had a 90% digestion rate. The p value for each sample was .05% which means that the results were considered statistically significant. The highest digestion rate of microplastic by Rhodococcus ruber was found in the soil pH of 5. This supports the idea that pH does have an impact on microbial biodegradation.

About this Scientist:

Abigail Gutierrez is a junior who is currently pursuing a Regents Diploma with a CTE certificate at Saunders Trade and Technical. She is going to apply to major in Biochemistry and minor in education or music at Columbia University next fall. After college she plans on enrolling in an M.D/PhD program and becoming a microbiologist, in order to pursue her dream of working in a lab and using microscopes to help the world. As well as showing that art and science go hand and hand.

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