Transposon liquid enrichment sequencing (Tn-LE Seq) involves the use of transposons, a type of mobile genetic element, to mutagenize cells growing in liquid growth media, and has been used to characterize essential genes by DNA sequencing of the affected areas. Transposon insertion into a gene with no loss of function helps differentiate nonessential from essential genes. The basis of the work presented is to serve as a foundation for a Tn-LE Seq experiment in the sulfate reducing bacterium, Desulfofustis glycolicus. This particular organism is of interest because it can metabolize sulfur in two distinct ways: disproportionation of elemental sulfur and sulfate reduction. By performing the Tn-LE Seq experiment during growth fostering either of these two modes of metabolism, we will be able to compare the essential genes for both of these metabolisms and determine candidate genes for sulfur disproportionation as the genes involved in sulfur disproportionation are not well characterized whereas those for sulfate reduction are very well understood.  Testing different antibiotics will make it possible to select for the transformed bacteria as the mutagenizing transposon for Tn-LE Seq (transferred via a plasmid from an E. coli donor) has an antibiotic resistance gene. Furthermore, by using different antibiotics at various concentrations it will be possible to decide which antibiotic at a given dosage is the most effective. Anoxic sulfate reducing media supplemented with a given antibiotic was inoculated with D. glycolicus in the stationary growth phase. Immediately after inoculation a sample was taken and cells were stained using DAPI for visualization and counted by fluorescence microscopy, this was repeated after thirty-five days to determine if cell growth had occurred. This experiment showed that kanamycin, gentamycin and spectinomycin were all effective in inhibiting growth of D. glycolicus. The results from this project will aid us in choosing what antibiotic resistance gene should be included with the transposon for conjugation and the necessary concentration for said antibiotic, thus allowing us to select for successfully conjugated D. glycolicus.