Feb 3, 2017
A Survey of Beta-lactam Antibiotic Resistance Genes and Culturable Ampicillin Resistant Bacteria in Minnesota Soils
Emily Wollmuth '17
Since the discovery of penicillin, antibiotics have been an essential tool in the treatment of bacterial infections and diseases. However, it is estimated that antibiotics and antibiotic resistance genes have been around for billions of years. With the increasing appearance of resistant pathogenic bacterial strains, there has been growing concern. β-lactam antibiotics make up the largest portion of the global market, so resistance to these antibiotics is especially alarming. It has been theorized that frequency and type of antibiotic resistance genes vary between areas. Previous studies have suggested that these differences may be related to antibiotic use in agricultural and urban areas. To survey this variation, soil samples were collected from 180 Minnesota locations and plated on LB media with and without ampicillin. Plates were incubated for 24 hours at 32˚C. DNA was isolated directly from soil samples, and each sample was tested for antibiotic resistance genes bla-1, bla-TEM, bla-SHV, OXA-23, OXA-24, OXA‑51, and OXA-58 using polymerase chain reaction (PCR). Samples were classified by land cover using data from the United States Geological Survey. By comparing colony counts on plates with and without ampicillin, approximate proportions of ampicillin resistant bacteria in different environments were identified. The results show that ampicillin resistant bacteria were present at most sites examined. The rates of resistance ranged from 0.00% to 93.75%, with the overall average resistance for all sites being 10.81%. The most common resistance genes were bla-1 and bla-TEM, which occurred at the average rates of 14.4% and 12.2% respectively. There was no correlation of land cover type with either of these resistance genes, or with any of the other genes examined. Antibiotic resistance genes are found in the human microbiome and mathematical modeling has shown that antibiotic resistance in hospitals is a result of genes from the surrounding area entering the clinical environment. Thus, increases in antibiotic resistant infections may be the result of existing antibiotic resistance genes that are prevalent in the environment being brought into clinics and hospitals where selection pressure results in them being maintained and spread.
Impacts of European Buckthorn on Arthropod Biodiversity
Rex Gould '17
The plants and animals living in a particular ecosystem play a role in determining what other forms of life may live in that ecosystem. Rhamnus cathartica (also known as common buckthorn) is an invasive shrub in North America that is no exception to this statement. Its aggressive behavior displaces native plant species and may also inhibit the biodiversity of arthropods and songbirds as the result of lower plant diversity. In this study, we examined woodland habitat points within 16 Minnesota parks. At each point vegetation, arthropod, and songbird censusing were used to assess the impact of various abundance of buckthorn on the biodiversity and species richness of plant and animal life. We found that arthropod diversity and species richness were greatly influenced by the presence of buckthorn in the shrub layer. This lead to greater arthropod diversity and richness with greater concentrations of buckthorn comprised the shrub layer. Higher concentrations of buckthorn presence also showed to have a negative influence on bird diversity.
