Honors Program

University Honors

Date of Award


Thesis Professor(s)

Sean James Fox

Thesis Professor Department

Health Sciences

Thesis Reader(s)

Ranjan Chakraborty


The recent rise of multidrug resistant microorganisms has grown from an isolated concern to a massive public health crisis. It has become imperative that scientists look for new ways to combat this issue. Due to the selective pressures of competition, bacteria and other microbes possess a host of defenses and weapons designed to exploit vulnerabilities in other microorganisms. Consequently, the study of these systems and microbial interactions has much to reveal in the search for novel antimicrobial treatments. Previous research from our laboratory has discovered that both Alcaligenes faecalis and Alcaligenes viscolactis, two rarely studied and generally non-virulent bacteria, exert a microbicidal effect on Candida albicans and Staphylococcus aureus, two pathogenic and frequently drug-resistant organisms. In this study, we confirmed that these effects are via a live-cell, contact-dependent mechanism and showed that both Alcaligenes species inhibit S. aureus at the attachment phase of biofilm growth. Additionally, we found that A. faecalis and A. viscolactis target Gram-positive bacteria outside the genus Staphylococcus and certain Gram-negative species as well as Candida glabrata. This study also provides novel evidence of a putative Type VI Secretion System in both Alcaligenes species, which may explain their antimicrobial phenotype. Despite efforts to identify the genetic elements involved via mutagenesis, the mechanism of these interactions remain elusive due to the difficulty of gene transfer in these organisms. We hope these results will increase current knowledge of Alcaligenes’ capabilities and genetic composition as well as establish the groundwork for future efforts to discover its inhibitory system and mechanisms.


East Tennessee State University

Document Type

Honors Thesis - Withheld

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