Improving Food Security: Biodiversity and Heterogeneity of Food-Spoilage Yeasts

Food spoilage by microorganisms has major impacts on the security of our food supply. Yeasts and moulds are estimated to cause annual food losses sufficient to feed 600 million people. This PhD project tackles this key problem through an academia-industry international collaboration, which offers cross-sector co-supervision and expertise together with a stipend uplift for the successful candidate. Food preservation helps to protect foods, but spoilage microorganisms such as yeasts may co-evolve to enable growth with common preservatives. Specific yeast species, strains and cell-subpopulations are still able to resist the major preservation methods. This is particularly true for preservation with weak acids and low pH, methods that are widely used in food design. However, the contributions of different resistance mechanisms to the overall risk of food spoilage by wild spoilage yeasts are not known. Recent work in our laboratories has shown significant differences in preservative resistance between strains of the same species, and even between individual cells of the same strain. This indicates that the phenotypic status of food spoilage yeasts enables them to overcome preservatives, e.g., by adopting semi-dormant states. These new insights hold great promise for application in improving food preservation and global food security. This studentship will develop this research by implementing a broad, quantitative strategy to tackle preservative resistance in spoilage yeasts.

The main project tasks will be:
• Characterise the phenotypic diversity of spoilage yeasts faced with acid preservatives and low pH.
• Identify key genetic elements responsible for acid resistance and its regulation in different spoilage yeast strains.
• Quantify and characterise the heterogeneity of acid resistance between individual yeast cells.
• Use predictive modelling to estimate the prevalence of the above resistance mechanisms and their importance for food spoilage.
• identify the minimum preservation level (pH and acid concentration) that is needed to control spoilage risk.

Training:
The project will provide outstanding training opportunities for the successful candidate, with supervision by a cross-disciplinary and cross-sector team. Training will be provided in molecular genetics tools applied to yeasts, bioinformatics, whole-genome sequencing, single-cell transcriptomics, and flow cytometry complemented by quantitative and predictive modelling approaches. The student will benefit from access to state-of-the-art facilities and dynamic research environments at the University of Nottingham, UK and at Unilever’s Global Foods Innovation Centre, Netherlands. There will be opportunities for travel and training credits for transferable skills relevant to diverse future-career destinations.

This PhD will be based primarily in the School Life Sciences, University of Nottingham. For further information or to apply, please contact Professor Simon Avery: [Email Address Removed]
Application should be by cover letter and CV, emailed to [Email Address Removed]


The PhD will be registered at the University of Nottingham which is one of the world’s most respected research-intensive universities, ranked 8th in the UK for research power (REF 2014). Students studying in the School of Life Sciences will have the opportunity to thrive in a vibrant, multidisciplinary environment, with expert supervision from leaders in their field. Students are closely monitored in terms of their personal and professional progression throughout their study period and are assigned academic mentors in addition to their supervisory team. The School provides structured training as a fundamental part of postgraduate personal development and our training programme enables students to develop skills across the four domains of the Vitae Researcher Development Framework (RDF). During their studies, students will also have the opportunity to attend and present at conferences around the world. The School puts strong emphasis on the promotion of postgraduate research with a 2-day annual PhD research symposium attended by all students, plus academic staff and invited speakers.