Degree Type

Thesis

Date of Award

2020

Degree Name

Master of Science

Department

Theses & dissertations (Interdisciplinary)

Major

Microbiology

First Advisor

Byron Brehm-Stecher

Second Advisor

Gregory Phillips

Abstract

Metal-sequestering compounds (chelators), such as the chemical compounds Ethylenediaminetetraacetic acid (EDTA) and long-chain polyphosphates, can enhance the uptake and activity of various antimicrobial compounds. Previous work has shown that chelation of structurally important divalent cations (Mg2+, Ca2+) from the outer membrane of Gram-negative bacteria is an effective route towards the permeabilization of these bacteria, leading to uptake or modulation of activity for co-applied antimicrobials, including membrane-active antimicrobials such as quaternary ammonium compounds. Similar antimicrobial-enhancing results have been shown for Gram-positive bacteria and fungi, presumably due to the chelation of analogous structurally-important cations. We hypothesize that, like EDTA and polyphosphates, naturally derived chelators can also play multifunctional roles as both antimicrobial enhancers and antioxidants, leading to potentially useful applications in "green" antimicrobial and chemical preservative formulations.

In this work, several candidate chelators (CCs) were identified from an initial literature search, with an emphasis also made toward identifying and prioritizing plant-based, value-added compounds that might promote clean- or clear-label labeling efforts. CCs were sourced, then assayed for their chelating activity using a modified Chrome Azurol S (CAS) colorimetric assay. Several potent natural chelators were identified using this approach, and phytic acid was evaluated further for its ability to enhance both cetylpyridinium chloride (CPC, a model quaternary ammonium compound) and novel pyrone antimicrobials synthesized by the Kraus laboratory at Iowa State. Our results suggest that chelation-based enhancement of antimicrobial efficacy represents a promising, "green" and value-added approach for the development of new antimicrobials for use in foods, sanitizer formulations, and related applications.

DOI

https://doi.org/10.31274/etd-20200624-231

Copyright Owner

Allison Brost

Language

en

File Format

application/pdf

File Size

52 pages

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