The role
Picocyanobacteria are microscopic algae that play a major role in global carbon cycling by capturing carbon dioxide (CO₂) for photosynthesis. They use highly specialised mechanisms to achieve this: actively transporting CO₂ and bicarbonate into their cells through dedicated membrane proteins. Inside their cells, they possess unique microcompartments called carboxysomes, which concentrate CO₂ around the enzyme RuBisCO — enhancing carbon fixation and reducing photorespiration. These structures are supported by enzymes known as carbonic anhydrases, which help regulate the balance between CO₂ and bicarbonate. Importantly, 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 evolutionary origins of the carboxysome and its connection to rising atmospheric oxygen levels. One critique of the oligotrophy hypothesis (which links carbon-concentrating mechanisms to nutrient-poor environments) 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 (NOE). In this view, the horizontal gene transfer (HGT) of carboxysome genes may reflect a response to rising O₂ rather than a driver of broader metabolic innovation. However, this idea conflicts with phylogenetic data on cyanobacterial evolution. Ancestral state reconstructions suggest that the last common ancestor of all modern cyanobacteria already possessed a β-type carbon-concentrating mechanism (β-CCM), which includes carboxysomes. Furthermore, molecular clock analyses place the origin of the CSP (carboxysome-specialising picocyanobacteria) clade firmly in the Neoproterozoic — implying that carboxysomes pre-date the NOE.
To test these competing interpretations, in this project, 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 alternative 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
- Download and analyse publicly available data from NCBI
- Computational analyses: develop tailor-made pipelines to analyse newly generated data, publicly genome 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
- Coordinate work with project partners
- 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 fortnightly project meetings with the Sanchez-Baracaldo research group.
- Participate in appropriate activities organised by the Sanchez-Baracaldo research group, including attendance at weekly webinars.
- Present research outcomes in other departmental seminars as required.
- Conduct necessary administrative tasks relating to laboratory work (e.g. Health and Safety assessments and documentation), ensuring compliance with relevant bodies.
- Engage effectively in the University’s Staff Review and Development process and develop, with advice, an awareness of their own professional development needs and a personal development strategy, engaging with continuing professional development appropriate to the role.
- May provide advice and demonstrate techniques to students in their discipline.
- 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 (e.g. equal opportunities, ethics and health and safety 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 at a later date.
Work pattern: Full time
Grade: J/Pathway 2
Salary: £43,482 - £50,253 per annum
School/Unit: School of Geographical Sciences
This advert will close at 23:59 UK time on 04/09/2025
For informal queries, please contact: Patricia Sanchez-Baracaldo [email protected]
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