FEMS Microbiology Reviews Poster Prize: Hamilton Green

We send our congratulations to Hamilton Green, who won best poster prize at the ASM Conference on Biofilms, sponsored by the FEMS Microbiology Reviews.

The ASM Conference on Biofilms took place on 13-17 November 2022 in Charlotte, NC.

Read our interview with Hamilton about his research below:


What is your current position, and what was your scientific journey to get there?

I am currently a 5th year Ph.D. candidate in the Microbe-Host interactions graduate program at Vanderbilt University. I am co-mentored by Drs. Maria Hadjifrangiskou, respected molecular microbiologist and Jonathan Schmitz, rising clinical microbiologist. I began my research career the freshmen year of undergraduate school with the Leadership Alliance First Year Research Experience (FYRE) summer program with my current mentor Dr. Hadjifrangiskou. Working with my graduate student mentor, my project focused on the evaluation of urinary serine and pyruvate levels from diabetic patients and how uropathogenic Escherichia coli (UPEC) levels contribute to an increase in the occurrences of urinary tract infections (UTI’s). UPEC causes the majority of UTI’s and are commonly acquired in community and hospital environments. In diabetic populations, the risk of developing a UTI is double that of non-diabetics. Participating in this research project allowed me to learn many new laboratory techniques.  I also increased my understanding of the how scientists conduct research, and I learned how to develop a stepwise approach to designing experiments geared toward answering research questions. Most importantly, I successfully completed my first full-time research experience, and I became certain that engaging in research would be my major future goal. There after I returned each summer to Vanderbilt to extend my microbiology passion and knowledge. These summer research programs and Dr. Hadjifrangiskou are extremely important as they gave me confidence and a glimpse into a world I never knew existed. Vanderbilt University and my current mentors have been an essential part of my success as a developing microbiologist.”


Could you describe the research your poster covered?

At ASM Biofilms 2022 I presented “Stochastic Lipoprotein Mutations that Impact Biofilm Morphology in uropathogenic Escherichia coli”. The project overall focus was to characterized colony biofilm phenotypic profiles of clinical Uropathogenic coli (UPEC) isolates spotted on agar containing the dye Congo red (CR) used to qualitatively show the abundance of curli and cellulose upon binding.

Observation of the CR-colony biofilm morphotypes led to the discovery of natural intra-strain heterogenous isolates we have termed as “peppermints”. These isolates have distinct increased CR- emergent subpopulations arising at the periphery of the colony biofilm and are differential from the parental less CR phenotype. Increased CR emergents retain their phenotypes after being isolated from “peppermint” isolates, allowing us to identify genetic mutations via next generation sequencing.

We identified several independent mutations that occurred in the outer-membrane lipoprotein gene nlpI. Each nlpI mutant colony biofilm morphology is altered having increased rugosity when compared to the wildtype phenotype. Deletion of nlpI in model isolate UTI89 phenocopies the natural nlpI mutants. Proteomic characterization of ΔnlpI determines an increase abundance of cellulose proteins in the outer membrane. Therefore, the identification of clinical UPEC intra-strain CR colony biofilms led to the discovery of stable nlpI mutations. These mutations can be leveraged to alter rugosity of colony biofilm morphologies by increasing curli/cellulose appendages. The difference of rugosity amongst emergent subpopulations could overall benefit the virulence or survival of these isolates during biofilm maturation.”


What do you hope to focus your research on in the future?

My plans in the foreseeable future are to matriculate in the field of Public Health after completing my doctorate. Unfortunately, the world has been impacted significantly by Covid-19 pandemic; however, the Public Health field has been vastly important in the progressive understanding of the virus. The field of Public Health contains several sectors at which I can implement my vast knowledge and understanding of microbes. I envision a field that allows me to continue to investigate the different phenotypic profiles of clinical microbial isolates and how these isolates impact the community through a Public Health viewpoint.”


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