PhD project: At the desiccation limit for life

Project description

Summary

In extreme deserts and in many environments of practical interest, such as hospitals, microorganisms are subjected to desiccation. Yet we still understand very little of the molecular events that occur under desiccation. This project will explore the biological changes to cells at the limits of water availability.

Project description

Microorganisms are known to produce structures that allow them to survive long periods of desiccation, such as spores. However, it is also possible for non-spore-forming microorganisms to persist in long-period desiccation by means of various molecular adaptations. Some of these are known, such as the production of trehalose or other compatible solutes that act to provide adaptation to osmotic stress, but much is still to be understood.

Survival at extremes of water stress is important in many contexts. Microbes that can survive extended desiccation can persist in extreme deserts, permafrost, ice and other habitats where the capacity for reproduction may be transient. Desiccation resistant can explain how microorganisms can survive in artificial settings such as hospitals or as potential agents of spoilage in food. Desiccation-resistant microbes may also occur on surfaces such as spacecraft and could have relevant for planetary protection (i.e. the potential contamination of extraterrestrial environments with organisms).

In this project, we will investigate the survival of several strains of desiccation resistant organisms that we have isolated in Edinburgh, specifically strains of Methylobacteria and other organisms which have survived desiccation for many years. We will study the adaptations they use as they undergo desiccation, using -omics and other approaches.

Research Questions

What are the dry limits to life?

What molecular mechanisms does life employ to survive long periods of desiccation?

What physical principles underly the adaptations to life in extreme conditions?

What implications do the molecular mechanisms for desiccation resistance have for microorganisms in medical, food and space settings?

Training

This project will involve training in microbiology and molecular methods relevant to the project. The project would suit someone with some background or experience in microbiology and/or molecular biology.

Methodology

The project will involve the use of aerobic and anaerobic microbiological methods to culture organisms. The investigation of desiccation resistance will be undertaken by using molecular methods, including omics approaches and related investigations.

The first year of the project will involve the study of the metabolomic responses of organisms to desiccation, accompanied by laboratory growth experiments. This year may also involve the isolation of novel desiccation resistant organisms from field sites.

The second year will involve the detailed molecular analysis of the adaptations of organisms to extreme desiccation and the study of the physical principles behind it.

The third year will involve the study whether non-desiccation resistant organisms can be made more desiccation resistant using knowledge gained in previous years.

Relevant papers

Lang, E., Rhee, M.S., Goncalves, M.P.M. and Sant’Ana, A.S., 2024. Desiccation strategies of Cronobacter sakazakii to survive in low moisture foods and environment. Trends in Food Science & Technology143, p.104241.

Cockell, C., 2015. A 500-year experiment. Astronomy & Geophysics56(1), pp.1-28.

Azua-Bustos, A., Urrejola, C. and Vicuña, R., 2012. Life at the dry edge: microorganisms of the Atacama Desert. FEBS letters586(18), pp.2939-2945.

Warren-Rhodes, K.A., Rhodes, K.L., Pointing, S.B., Ewing, S.A., Lacap, D.C., Gomez-Silva, B., Amundson, R., Friedmann, E.I. and McKay, C.P., 2006. Hypolithic cyanobacteria, dry limit of photosynthesis, and microbial ecology in the hyperarid Atacama Desert. Microbial ecology52, pp.389-398.

Project supervisor

The project supervisor welcomes informal enquiries about this project.

Find out more about this research area

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