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BBSRC FoodBio Systems DTP - Repurposing artificial sweeteners as infection and contamination control agents

This project is supervised by Dr Ronan McCarthy - Brunel University London and Co-supervisor: Brendan Gilmore, Queen's University Belfast

Project description 

Artificial sweeteners are a group of compounds that have a significantly higher sweetening power than sucrose but have little to no calorific contribution. Because of these properties, artificial sweeteners have become staples in the human diet with many companies offering “Zero” or “Sugar Free” alternatives to typically high sugar products. While there have been extensive studies investigating the impact of these sweeteners on the human body (Carocho et al.,2017), there have been relatively few studies looking at the impact on bacteria in the human body. However, these is emerging evidence that artificial sweeteners can significantly alter the gut and oral microbiome and that these changes can have an impact on human health (Suez et al.,2022). A recent study by the McCarthy lab has demonstrated that a number of these artificial sweeteners possess antimicrobial properties with the highly popular sweetener acesulfame-K (ace-K) in particular, being able to inhibit bacterial movement, their ability to acquire antibiotic resistance genes from the environment and their ability to grow.


Bacterial infection is a major challenge to the agrifood sector with wound infections such as digital dermatitis (DD) (a wound infection of the hoof which leads to lameness) having a major impact of livestock welfare and presenting a significant economic challenge (Palmer & O’Connell., 2015). DD is highly prevalent particularly in dairy farms with 70-95% of herds showing signs of digital DD. The treatment of such wound infections in livestock presents a number of challenges such as the restricted contact time between the site of infection and the treatment, and the formation of bacterial communities called biofilms within the wounds. Biofilms are communities of bacteria encased in polysaccharide matrix, by growing in biofilms, bacteria are between 10-1,000 more resistant to antibiotic therapy and chemical disinfection (Maslova et al.,2021). The increasing restrictions on the use of antibiotics in agriculture also complicates the treatment landscape (Manyi- Loh et al.,2018).

Bacterial contamination in food processing is a major cause of foodborne illness, food spoilage and production pipeline shuts downs. This contamination is particularly problematic and difficult to eradicate when bacteria adopt the biofilm mode of growth. These biofilms can form within key parts of the food processing infrastructure leading to costly plant shuts downs and damaging decontamination procedures (Galie et al.,2018).In this project, we will explore the ability of the artificial sweetener, ace-K , to treat livestock-associated wound infections and assess its ability to act as a surface decontamination agent.

We will address this through three distinct but interlinked objectives.

  1. Determine the ace-K spectrum of antimicrobial activity (BUL): In this objective, we will investigate which foodborne pathogens are susceptible to the antimicrobial activity of ace-K and at what concentrations. We will also explore the basic physiological consequences of ace-K exposure to these pathogens using live cell imaging. To determine if ace-K can influence the transmission of antibiotic-resistance genes within livestock, we will use a simulated porcine gut microbiota model and an ex vivo skin microbiota model.
  2. Investigate the ability of artificial sweeteners to treat wound infections in livestock (BUL &QUB): Ace-K has been shown to be effective at preventing biofilm formation and disrupting established biofilms. This proposal will explore its ability to treat and prevent wound infections in livestock using ace-K wash solutions and ace-K loaded hydrogel wound dressings in an ex-vivo porcine wound model.
  3. Determine the capacity of artificial sweeteners to decontaminate contaminate surfaces (BUL &QUB): We will use 3D printed replica models of food processing pipelines and surfaces to assess the ability of ace-K loaded wash solutions to prevent surface contamination or to cause biofilms on contaminated surfaces or model pipelines.Ace-K is a compound consumed by millions of people around the world on a daily basis and its ability to prevent pathogen growth has only recently been recognised. This project will build on this finding by generating new insights into the fundamental biology of how ace-K kills foodborne pathogens and assessing its capacity be used as an infection and contamination control agent. Repurposing this food additive as a biocontrol agent could offer viable therapeutic and decontamination solutions to a variety of stakeholders in the agri-food sector.


Training opportunities:

The prospective student will gain experience and training in a wide range of molecular biology and microbiologicalmethods. This will include live cell imaging and within-host horizontal gene transfer assays. They will also gene experience in pharmaceutical formulation and wound therapy development as well as in ex-vivo porcine wound assays to determine treatment efficacy. The student will also gain experience in computer-aided design, 3D printing and in the use of flow cell biofilm assays. The student will also play a central role in communicating project goals and progress with stakeholders.

Student profile:

This project would be suitable for students with a strong interest in antibiotic resistance and biofilms with a BSc honours degree at an upper second-class level (or equivalent) in Microbiology/Biomedical Sciences or a closely related subject. Stipend (Salary): FoodBioSystems DTP students receive an annual tax-free stipend (salary) that is paid in installments throughout the year. For 2022/23 this will be £19,668 (including London allowance) and this will increase slightly each year at the rate set by UKRI.

How to apply

How to apply for a studentship

  • Please apply using the online application form, whether the project/s you are interested in are based at Reading, Surrey, Cranfield, Queen’s, Aberystwyth or Brunel. We do not accept CVs.
  • You will be able to apply to a maximum of TWO PhD projects. Each project description indicates the name and institution of the lead supervisor and has a project ID number. You are welcome and encouraged to email the lead supervisors of projects to ask them any questions you may have or to discuss the project.
  • You will need the following documents to support your application
    • Official transcripts of your higher education qualifications, inclusive of grades
    • Evidence of your proficiency in English, if English is not your first language.
  • You will also be asked to provide the name and email address of someone who will provide a confidential academic reference letter. The DTP office will request the letter from your referee if you are shortlisted for interview
  • Closing date is Monday 30 January at 10.00 am (GMT).

Please go to the end of the project summary table to read important information about applicant eligibility and our selection process. It is essential that you read this before you apply for a studentship.

The FoodBioSystems DTP is committed to equality, diversity and inclusion (EDI), to building a doctoral researcher(DR) andstaff body that reflects the diversity of society, and to encourage applications from under-represented and disadvantagedgroups. Our actions to promote diversity and inclusion are detailed on the FoodBioSystems DTP website.In accordance with UKRI guidelines, our studentships are offered on a part time basis in addition to full time registration.The minimum registration is 50% FT and the studentship end date will be extended to reflect the part-time registration.

Meet the Supervisor(s)

Ronan Mccarthy - Ronan gained his Bachelor of Science in Genetics with first class honours from University College Cork, Ireland in 2010 and was awarded the title of College Scholar. In autumn 2010, Ronan was awarded an Irish Research Council PhD Scholarship to study novel biofilm inhibition strategies against the opportunistic pathogen Pseudomonas aeruginosa in the lab of Professor Fergal O’Gara. In 2014, Ronan joined the research group of Professor Alain Filloux at the MRC Centre for Bacteriology and Infection at Imperial College London. As a Postdoctoral Research Associate, Ronan interrogated the second messenger signalling cascades that govern the biofilm mode of growth in Pseudomonas aeruginosa and Agrobacterium tumefaciens. Following on from his time at Imperial College Ronan joined the Microbiology Department at the Animal and Plant Health Agency where he used host transcriptomics and pathway analysis to profile the host response to infection. He joined the Biosciences Division in Brunel University to continue his analysis of the regulatory networks that govern pathogenicity, antimicrobial resistance and biofilm formation in the Gram negative opportunistic pathogens Pseudomonas aeruginosa and Acinetobacter baumannii. In 2021, Ronan was awarded a BBSRC New Investigator Award to study the regulation of desiccation tolerance and biofilm formation in Acinetobacter baumannii and to identify compounds that could disrupt these survival mechanisms.