Abstract
In recent years antibiotic resistant strains of bacteria have increasingly become a problem and pose a global threat. Several problematic bacteria utilize a type III secretion system (T3SS) to infect their host. T3SSs are needle-like appendages on the bacteria used to inject the host cell with toxins which disrupts the cell's defense. Hence, the T3SS would be agood target for a novel antibiotic drug. The goal of this study is to develop an assay to screen for compounds that inhibit bacterial T3SSs. Y. enterocolitica uses a T3SS to cause gastroenteritis and will be utilized as the test organism. A disc diffusion assay on congo red-magnesium oxalate agar (CR-MOX) will be used to detect inhibitors of T3S. Previous studies demonstrated that low levels of Ca2+ triggered secretion of toxins which simultaneously restricts bacterial growth at 37°C. The CR-MOX agar contains a Ca2+ chelator, which sequesters Ca2+ from the agar. The lack of Ca2+ and incubation at 37°C will induce toxin secretion and restrict bacterial growth. Therefore, bacteria will grow in smaller red colonies, which indicate that they are secreting the toxins. Disks inoculated with different compounds will be placed on CR-MOX agar plates containing 100-200 bacteria and incubated overnight at 37°C. Inhibition of the toxin secretion will be indicated by growth of large, white colonies around the disk. The development of this assay will be a useful, quick and inexpensive way to screen for possible compounds that may inhibit T3S secretion.
Faculty Sponsors
Julie Torruellas Garcia, Ph.D.
Project Type
Event
Location
Alvin Sherman Library
Start Date
4-10-2015 1:00 PM
End Date
4-10-2015 5:30 PM
A Novel Assay to Screen Drugs that Target Bacterial Type III Secretion Systems
Alvin Sherman Library
In recent years antibiotic resistant strains of bacteria have increasingly become a problem and pose a global threat. Several problematic bacteria utilize a type III secretion system (T3SS) to infect their host. T3SSs are needle-like appendages on the bacteria used to inject the host cell with toxins which disrupts the cell's defense. Hence, the T3SS would be agood target for a novel antibiotic drug. The goal of this study is to develop an assay to screen for compounds that inhibit bacterial T3SSs. Y. enterocolitica uses a T3SS to cause gastroenteritis and will be utilized as the test organism. A disc diffusion assay on congo red-magnesium oxalate agar (CR-MOX) will be used to detect inhibitors of T3S. Previous studies demonstrated that low levels of Ca2+ triggered secretion of toxins which simultaneously restricts bacterial growth at 37°C. The CR-MOX agar contains a Ca2+ chelator, which sequesters Ca2+ from the agar. The lack of Ca2+ and incubation at 37°C will induce toxin secretion and restrict bacterial growth. Therefore, bacteria will grow in smaller red colonies, which indicate that they are secreting the toxins. Disks inoculated with different compounds will be placed on CR-MOX agar plates containing 100-200 bacteria and incubated overnight at 37°C. Inhibition of the toxin secretion will be indicated by growth of large, white colonies around the disk. The development of this assay will be a useful, quick and inexpensive way to screen for possible compounds that may inhibit T3S secretion.
