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ABSTRACT Fluorescent Tracking of Horizontal Gene Transfer in Gut Microbes

Abstract: The human gut microbiome is diverse both in composition and in function. Further, changes in the microbiome can contribute to both health and disease. Many of these microbes can swap genes in a process called horizontal gene transfer (HGT). This allows microbes to gain advantageous phenotypes such as antibiotic resistance, the ability to consume different nutrients, and/or produce cell coatings that allow them to avoid a host’s immune system. Tracking these transfer events is challenging, particularly if it is unclear which parts of the genome of a microbe can or can’t be transferred. Here, I propose examining transfer events using anaerobic fluorescent proteins (AFPs) combined with transposon mutagenesis. First, I tested a panel of 4 novel AFPs for the ability to be expressed and detected in the model gut microbe Bacteroides thetaiotaomicron VPI-5482. I then used transposon mutagenesis to randomly insert the AFPs into several species of gut microbe (donors) and after co-culturing them with unmodified species (recipients), in an attempt to identify recipient cells that acquired the AFPs. Once confirmed, regions of mobile DNA responsible for transferring the AFP can be characterized. This approach offers a novel way to rapidly detect HGT events in complex gut microbe communities and find new functional genes that contribute to a microbe’s ability to colonize the human gut.