A Search for Type III Secretion System Inhibitors Produced by Soil Bacteria

A Search for Type III Secretion System Inhibitors Produced by Soil Bacteria

Due to the misuse of antibiotics, antibiotic resistant bacteria have become prevalent in modern day. To circumvent this, instead of directly affecting bacterial growth with antibiotics, the virulence factors can be targeted. Type III secretion system (T3SS) pathogens exude toxins through needle-like protrusions found on their cell membrane. If the secretion of these toxins is inhibited, then the severity of the illness will be reduced. The purpose of this research is to find a T3SS inhibitor for pathogens through the analysis of soil bacteria. While T3SS pathogens are known to target humans, many are soil-dwelling plant pathogens. By studying the bacterial composition of the soil near plants with resistance/immunity to the pathogens, T3SS inhibitors may be found. To isolate and test bacteria for T3SS inhibition, soil samples of plants with resistance to high-temperature T3SS pathogens e.g. Xanthomonas axonopodis(citrus canker) were collected. Then, soil dilutions and patch plating were used to isolate the soil dwelling bacterium that grow in conditions ideal for the T3SS pathogens. These bacteria were tested against the ESKAPE alternative pathogens for antibiotic activity, and it was shown that five isolates had some form of antibiotic activity against the ESKAPE alternative pathogen. These bacteria will be tested against Yersinia pestis for T3SS inhibition.