Group 12: Continental-Scale Pollution of Estuaries with Antibiotic Resistance Genes

Group 12: Continental-Scale Pollution of Estuaries with Antibiotic Resistance Genes


Beginning in the 1940s, humans have produced and used antibiotics on a large scale in order to help our bodies fight off infections. Antibiotics fight infections by killing the bacteria or by making it hard for them to multiply. Unfortunately, these antibiotics are a pollutant to the environment, and humans as well. In 2013 in China alone, approximately 53,800 tons of antibiotics were dumped into rivers and other waterways. This directly affects the ecosystem ecology of the waterways by affecting the soil and water that various organisms interact with. This especially impacts bacteria because the antibiotics act as a selective pressure. The few resistant bacteria that aren’t killed have the chance to pass on or transfer their genes to their offspring or other bacteria, causing the bacteria population to evolve overall. The genes that prevent the bacteria from being harmed by the antibiotics are known as antibiotic resistance genes or ARGs. Estuaries are a hotbed for ARGs. As rivers flow out into the ocean, they pass through an estuary, which acts as a boundary or filter between the terrestrial and marine ecosystems. Consequently, human impact on the environment is greatly amplified in estuaries. In order to better understand our impact as humans, Yong-Guan Zhu, Yi Zhao, and their team in China set out to gather data on the ARG composition of various estuarine ecosystems. They took 5 soil samples from each of 18 estuaries stretching over 4,000 km of the Chinese coast, for a total of 90 samples. The soil samples were then tested for the presence of 285 different ARGs, and it was found that each estuary contained between 85 and 158 different ARGs, and 248 of the ARGs were found in total. 18 ARGs were present in all 90 samples. One gram of soil was found to contain between 880,000 and 180,000,000 copies of antibiotic resistance genes. But beyond these numbers, the researchers wanted to look for trends or correlations that would explain the ARG make-up of estuarine ecosystems. Previous studies of ARGs in China involved samples from only one location and did not check for as many different ARGs. The widespread collection of data in this experiment, however, allowed for the discovery of significant correlations between population, GDP, and sewage production with the abundance of ARGs. This implies that factors such as the large population and economic expansion of China may serve to promote the spread of ARGs in estuaries. A partial redundancy analysis (pRDA) was used to connect antibiotic concentrations to environmental, bacterial, and anthropogenic, or human, causes. Human factors alone account for 27% of the variety of the ARG profile and over 64% when including interactions with the environmental and bacterial factors. Humans are the primary culprit responsible for the quantity and diversity of ARGs in estuarine ecosystems. Antibiotic resistance genes typically encode proteins that function to deactivate antibiotics, pump the antibiotics out of the cell, or prevent the antibiotics from entering the cell in the first place. As bacteria populations evolve and pass on ARGs to their offspring, the risk of formation of resistant pathogens increases. Eventually, it is possible that some strains of bacteria could become untreatable by current medical technology. Antibiotics and ARGs are pollutants to humans, the environment, and all organisms exposed to antibiotic-resistant bacteria and need to be treated as such through serious regulations. Thanks for watching! (^ω^)

2 Replies to “Group 12: Continental-Scale Pollution of Estuaries with Antibiotic Resistance Genes”

  1. hi, i was wondering if you could pls put a link of the original findings of Zu and Zhao mentioned in this video, thank you so much

  2. Thank you very much for the interesting video about a very critical issue that human been facing in a new era.

    Please, add more details about the original study that you provided the information from.

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