The gut microbiome is home to several species of bacteria and other microorganisms that play an essential role in human health. For example, the normal bacteria in our gut provide resistance to pathogenic species and directly impact nutrient metabolism, such as the production of vitamin K. Carnitine, which is a molecule commonly found in seafood and red meat products, is broken down by many species of gut bacteria to produce trimethylamine (TMA) as a byproduct. TMA is then converted in the liver to trimethylamine-N-oxide (TMAO), which enters the circulation. Relatively high levels of serum TMAO have been linked to an individual’s risk for cardiovascular diseases such as atherosclerosis and abdominal aortic aneurysms (AAA). The Ferguson lab isolated a strain of the normal gut bacteria Citrobacter amalonaticus, called CJ25, that does not produce TMA upon carnitine catabolism. The breakdown pathway is not yet known, and determining this pathway has been a focus of the Ferguson lab. After culturing CJ25 in anaerobic conditions with carnitine as a sole carbon source, we gathered liquid chromatography mass spectrometry (LCMS) data in collaboration with The Ohio State University. Metabolites produced by bacteria grown in carnitine and in a glucose control were compared to identify significant differences. Upon initial analysis, there are significant differences in metabolites between glucose and carnitine samples, but these metabolites require further analysis. Data obtained through LCMS can then be used in conjunction with proteomic data and enzyme activity analysis to assemble a novel pathway for CJ25 carnitine degradation. This experience has provided me with invaluable hands-on laboratory experience, and the connections to cardiovascular health are directly related to my interest in a career in medicine.
Author(s): Ryan Gora, Microbiology Major
Advisor(s): D.J. Ferguson, Department of Microbiology
Roshan Timsina, Department of Microbiology
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