Date of Award

Summer 7-26-2024

Degree Type

Thesis

Degree Name

Master of Science in Integrative Biology (MSIB)

Department

Department of Ecology, Evolution, and Organismal Biology (EEOB)

Committee Chair/First Advisor

Thomas McElroy

Second Advisor

Christopher Cornelison

Third Advisor

Andrew Haddow

Abstract

Antibiotic resistance is a growing public health concern worldwide, and for over a decade, we have been witnessing the growth of difficult to treat infectious diseases caused by bacteria that are becoming resistant to antibiotics. This resistance can be mostly related to the misusing and improper use of antibiotics in both humans and animals. To restore this problem, humans have turned to new sources for the production of antibiotics. In this study, we focused on using ants. Social insects, including ants and bees, have faced strong disease pressures during their evolution and have developed a range of methods to fight or slow the spread of disease. One of these mechanisms is the development of antimicrobial compounds that ants and bees secrete onto their external body surface. Our previous work has shown that many, but not all, ant species produce strong, broad-spectrum antimicrobials, but this assay used only a polar extract (ethanol) and focused on one gram-positive microbe (Staphylococcus epidermidis). Here we discuss new work testing four solvents that vary in polarity from most polar to non-polar: ethanol (EtOH), isopropanol (iso-OH), dichloromethane (DCM), and hexane (HEX). In addition, we tested each extract against three different microbes: a gram-positive bacterium Staphylococcus epidermidis, a gram-negative bacterium, Escherichia coli, and an emerging fungal pathogen, Candida auris. We tested each combination with seven species of ants that represent three different ant sub-phyla: Solenopsis invicta (Myrmecinae), Brachyponera chinensis (Ponerinae), and Prenolepis imparis (Formicinae). Previous work showed that S. invicta and P. imparis produce antimicrobial effective against S. epidermidis using a polar solvent (ethanol), and we predict that we will see differences in extract activity using non-polar solvents and against different microbes, in this case E. coli. Previously we found no evidence of antimicrobial activity from extracts of B. chinensis, but we predict that we may see antimicrobial activity when using different solvents or against different microbes. Ultimately, this work will shed light on the evolution and specificity of antimicrobial compounds in ants and could identify future antibiotics for human use.

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