The Effects of Dysregulating Cyclic-di-GMP Pathways on Survival of Salmonella in Chicken Eggs
Location
Culp Room 304
Start Date
4-6-2022 1:00 PM
End Date
4-6-2022 2:00 PM
Faculty Sponsor’s Department
Health Sciences
Name of Project's Faculty Sponsor
Erik Petersen
Additional Sponsors
Bert Lampson, Jennifer Hall
Competition Type
Competitive
Type
Oral Presentation
Project's Category
Microbiology
Abstract or Artist's Statement
In a world with growing resistance to existing antibiotics, new approaches to finding new antibacterials are essential to fighting infections. Concerningly, antibiotic resistance is a growing problem in commercialized farming, where contaminated chicken eggs contribute to causing an estimated 142,000 cases of Salmonella infections in the U.S. every year. Cyclic di-GMP (CDG) is a secondary messenger molecule that Salmonella uses to regulate many signaling pathways in response to the environment, including desiccation tolerance and biofilm production. Certain primary stimuli from the environment will cause Salmonella to make CDG, which will bind to an effector molecule to initiate a signaling pathway for a desired response. The ability to disrupt this pathway could showcase a new potential target for new therapeutics. I hypothesized that by dysregulating the CDG response in Salmonella Typhimurium, the survival of the bacterium on eggshells or in egg whites would be affected. Therefore, we investigated survival of S. Typhimurium in the presence of two known CDG modulators, L-arginine and salicylic acid, in the egg white and on the eggshell. L-arginine was previously found to activate production of CDG in S. Typhimurium, while salicylic acid was found to lower CDG levels. Bacteria were exposed to either L-arginine or salicylic acid (or plain media as a negative control) and tested for survival either within egg white or after two days of desiccation on an eggshell. Assessments were also made with bacterial strains that did not have proteins associated with the CDG pathway: BcsA, a CDG-responsive cellulose synthase that produces biofilm-forming exopolysaccharide and STM1987, the L-arginine-response diguanylate cyclase that generates CDG. In the presence of L-arginine, S. Typhimurium survival significantly increased within egg whites compared to wild-type, while salicylic acid exhibited no change in survival. Deletion mutants of BcsA or STM1987 showed similar results, implying that CDG-mediated cellulose synthesis may not be directly involved in L-arginine survival. This work is the foundation for further analysis of chemical inhibitors of S. Typhimurium in egg whites and on the surface of eggshells. We also plan to examine other naturally occurring compounds as well as do transposon analysis to further understand these signaling pathways and potentially present a new target for new antibiotics.
The Effects of Dysregulating Cyclic-di-GMP Pathways on Survival of Salmonella in Chicken Eggs
Culp Room 304
In a world with growing resistance to existing antibiotics, new approaches to finding new antibacterials are essential to fighting infections. Concerningly, antibiotic resistance is a growing problem in commercialized farming, where contaminated chicken eggs contribute to causing an estimated 142,000 cases of Salmonella infections in the U.S. every year. Cyclic di-GMP (CDG) is a secondary messenger molecule that Salmonella uses to regulate many signaling pathways in response to the environment, including desiccation tolerance and biofilm production. Certain primary stimuli from the environment will cause Salmonella to make CDG, which will bind to an effector molecule to initiate a signaling pathway for a desired response. The ability to disrupt this pathway could showcase a new potential target for new therapeutics. I hypothesized that by dysregulating the CDG response in Salmonella Typhimurium, the survival of the bacterium on eggshells or in egg whites would be affected. Therefore, we investigated survival of S. Typhimurium in the presence of two known CDG modulators, L-arginine and salicylic acid, in the egg white and on the eggshell. L-arginine was previously found to activate production of CDG in S. Typhimurium, while salicylic acid was found to lower CDG levels. Bacteria were exposed to either L-arginine or salicylic acid (or plain media as a negative control) and tested for survival either within egg white or after two days of desiccation on an eggshell. Assessments were also made with bacterial strains that did not have proteins associated with the CDG pathway: BcsA, a CDG-responsive cellulose synthase that produces biofilm-forming exopolysaccharide and STM1987, the L-arginine-response diguanylate cyclase that generates CDG. In the presence of L-arginine, S. Typhimurium survival significantly increased within egg whites compared to wild-type, while salicylic acid exhibited no change in survival. Deletion mutants of BcsA or STM1987 showed similar results, implying that CDG-mediated cellulose synthesis may not be directly involved in L-arginine survival. This work is the foundation for further analysis of chemical inhibitors of S. Typhimurium in egg whites and on the surface of eggshells. We also plan to examine other naturally occurring compounds as well as do transposon analysis to further understand these signaling pathways and potentially present a new target for new antibiotics.