A One Health Investigation of Soil Extracellular Enzymes as Regulators of Antimicrobial Resistance Dynamics in Agricultural Systems

Apply and key information

Summary

Rationale and Background: Antimicrobial resistance (AMR) is one of the most pressing One Health threats globally, jeopardising public health, veterinary medicine, and agricultural sustainability. While clinical resistance dynamics are widely documented, agricultural soils act as extensive environmental reservoirs for antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) capable of transferring multidrug resistance across the food chain.

Existing environmental surveillance approaches primarily focus on direct antibiotic residue levels or simple ARG abundance counts. However, these approaches fail to explain the ecological mechanisms governing why ARGs persist and disseminate in natural soil systems long after antibiotic pressures subside.

Extracellular enzymes—such as glucosidases, proteases, and phosphatases—drive the rate-limiting steps of carbon, nitrogen, and phosphorus cycling in soil. This project addresses a fundamental knowledge gap by testing the novel hypothesis that enzyme-mediated nutrient turnover creates distinct metabolic microzones that regulate microbial physiological stress, competitive fitness, and horizontal gene transfer (HGT).

Methodology & Work Plan:

Field Mapping & Characterisation: The student will collect and analyze 250 agricultural soil samples across Northern Ireland to profile key C-, N-, and P-cycling extracellular enzyme activities using high-throughput fluorometric assays. In parallel, quantitative PCR (qPCR) and shotgun metagenomic sequencing will map ARG profiles, resistome diversity, and key mobility markers (such as intI1).
Functional Microbiology & Mechanism: To establish direct cause-and-effect relationships without the work-heavy burden of prolonged microcosm studies, targeted laboratory assays will evaluate bacterial conjugation efficiency (filter-mating) and plasmid stability across varied C:N:P stoichiometric ratios. Relative growth kinetics and stress-response assays will quantify the metabolic costs and benefits of maintaining resistance traits under different nutrient supply regimes.
Data Integration & Risk Modelling: Advanced multivariate statistical modelling, network co-occurrence analysis, and machine learning approaches will integrate soil biogeochemistry, enzyme kinetics, and genomic data to identify functional predictors of environmental AMR risk across regional catchments.

This project requires a bench fees of £10k which will be used in research consumables and the dissemination and publication of the research findings.

Essential criteria

Applicants should hold, or expect to obtain, a First or Upper Second Class Honours Degree in a subject relevant to the proposed area of study.

We may also consider applications from those who hold equivalent qualifications, for example, a Lower Second Class Honours Degree plus a Master’s Degree with Distinction.

In exceptional circumstances, the University may consider a portfolio of evidence from applicants who have appropriate professional experience which is equivalent to the learning outcomes of an Honours degree in lieu of academic qualifications.

Sound understanding of subject area as evidenced by a comprehensive research proposal detailing background, research questions, aims and methodology
A comprehensive and articulate personal statement demonstrating interest in the subject area

Desirable Criteria

If the University receives a large number of applicants for the project, the following desirable criteria may be applied to shortlist applicants for interview.

Applicants should hold, or expect to hold a First Class Honours Degree in a relevant subject area
International applicants should hold, or expect to hold a relevant Masters Degree at a level equivalent to a distinction at Ulster
Practice-based research experience and/or dissemination
Work experience relevant to the proposed project
Experience of presentation of research findings

Equal Opportunities

The University is an equal opportunities employer and welcomes applicants from all sections of the community, particularly from those with disabilities.

Appointment will be made on merit.