The role

Picocyanobacteria play a major role in global carbon cycling by capturing carbon dioxide for photosynthesis. They use specialised mechanisms to achieve this: transporting CO₂ and bicarbonate into their cells through dedicated membrane proteins. Inside their cells, they possess unique microcompartments which concentrate CO₂ around the enzyme RuBisCO — enhancing carbon fixation and reducing photorespiration. These structures are supported by carbonic anhydrases. Picocyanobacteria are able to adjust their carbon-concentrating machinery depending on environmental CO₂ availability. This project will investigate how and when these mechanisms evolved, particularly in the context of changing environmental pressures through time.

A key debate in the field concerns the origins of the carboxysome and its connection to rising atmospheric oxygen levels. One critique of the oligotrophy hypothesis is that carboxysomes may have evolved not just to improve CO₂ uptake, but also to shield RuBisCO from O₂. This protective role would have become more important as atmospheric oxygen increased during the Neoproterozoic Oxygenation Event. The horizontal gene transfer of carboxysome genes may reflect a response to rising O₂ rather than a driver of broader metabolic innovation. Ancestral state reconstructions suggest that the last common ancestor of all modern cyanobacteria already possessed a β-type carbon-concentrating mechanism, which includes carboxysomes. Molecular clock analyses place the origin of the CSP clade firmly in the Neoproterozoic.

To test these competing interpretations, we will use Bayesian statistics and phylogenetic methods to evaluate whether the timing of CSP clade evolution and HGT events are consistent with the oxygenation timeline. This will involve testing three hypotheses about the origin and spread of carboxysome genes across cyanobacteria. The results will clarify how key innovations in carbon fixation were shaped by Earth’s changing atmosphere and shed light on the co-evolution of microbial metabolism and planetary conditions.

What will you be doing?

Research Responsibilities

• Extract DNA from cyanobacterial cultures from culture collections
• Carry out genome assembly and annotation from non-axenic and/or axenic cultures
• Computational analyses: develop tailor-made pipelines to analyse newly generated data
• Carry out phylogenomic, molecular clock and Stochastic mapping analyses (e.g. sMap)
• Curate data generated in the project and make it available in NCBI
• Write up analyses and results including manuscript for publication

Administration Responsibilities

• Contribute to the writing of publications for dissemination of the research in the scientific literature.
• Participate in appropriate activities organised by the Sanchez-Baracaldo research group, including attendance at weekly webinars.
• Present research outcomes
• Conduct administrative tasks relating to laboratory work
• Engage in the University’s Staff Review and Development process
• Consistently act as a good citizen, actively participating in the daily working life of the School of Geography.
• Undertake relevant training and development activities to develop capacity for taking on wider responsibilities (including small amounts of teaching) and to support their career development.
• Maintain academic standards and freedom, and work in accordance with University policies

You should apply if

• A good honours degree (or equivalent) with subject knowledge in Biology, Mathematics
• A Ph.D. in Evolutionary Biology, Phylogenomics. Ph.D or equivalent professional experience in the research area required.

Additional information

Contract type: Open ended with fixed funding for 13 months.

There is a possibility of extension for up to an additional 1.5 years subject to confirmation.

Please see the full advert on the University of Bristol website for complete details and information on how to apply.