An investigation into the multiple Type VI Secretion Systems of Enterobacter cloacae
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Enterobacter cloacae is a Gram-negative, opportunistic bacterial pathogen that is commonly acquired by patients in hospitals. The Type VI Secretion System (T6SS) is a harpoon-like apparatus that injects toxins into the cell envelop of neighboring bacteria to defend or compete for resources. It’s commonly found in a range of bacteria including Vibrio cholerae, Pseudomonas aeruginosa, and Escherichia coli. Previous research in this lab has shown that E. cloacae kills in a contact dependent manner and bioinformatic analysis found three vask genes, which encode for a protein in the Type VI apparatus. We created three single mutant strains (Δvask1, Δvask2, Δvask3) as well a double mutant (Δvask1Δvask3). These strains were tested in competition assays with target WT E. coli, with the survival of the target being indicative of E. cloacae killing ability. We show here that Δvask2 had no change in killing ability, Δvask1 and Δvask3 had some reduction in killing ability, and Δvask1Δvask3 had a complete reduction in killing ability. This initial result suggests E. cloacae in vitro killing ability is dependent on two T6SSs.