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How does the unusual metabolism of cable bacteria impact iron and sulfur cycling in coastal sediments. (CLARKE_UBIO23ARIES)

   School of Biological Sciences

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  Dr T Clarke, Prof Jon Todd, Prof J Butt  No more applications being accepted  Competition Funded PhD Project (Students Worldwide)

About the Project

Scientific background  

Microbes known as cable bacteria grow vertically in 10 cm filaments that span both the anoxic and oxic zones of aquatic sediments.  They uniquely make energy by coupling the oxidation of reduced compounds in the anoxic zone to the reduction of oxygen, and so are not restricted by the availability of oxidised compounds in the anoxic zone (1).  

This likely influences the physiology and metabolism of the local microbial community as well as biogeochemical cycling, but the nature of these effects have not yet been investigated.  This is because these organisms were only identified by our collaborators at Aarhus university a decade ago.   

Despite recent advances, the physiology and environmental impact of these organisms is poorly understood.  In our pilot studies we show the cable bacterium Candidatus electrothrix to be relatively abundant in diverse iron and sulfur rich coastal sediments throughout the year.  These abundances fluctuate over seasons, and are consistent with fluctuations observed with the relative abundances of iron and sulfur species (2). 

Research methodology  

The student will establish methods to enrich cable bacteria in the UK, and to measure their abundance and activity in situ, supported by our collaborators who are the world experts in this field.  They will study the relative abundance of different chemical species in sediments enriched for cable bacteria with sediments that have not been enriched.  This will allow the impact of these organisms to be accurately addressed across a range of scientific areas, including changes in distribution of the redox active elemental species such as nitrogen and sulfur and the metagenomic distribution of other micro-organisms (3). 


The student will spend 12 months at Aarhus University learning to work with cable bacteria, including how to culture them and to determine their activity.  They will receive training in environmental analysis of metals and their different redox states as well as differentiating between different sulfur species in order to determine how the sediment composition is affected.  They will learn environmental DNA extraction techniques and metagenomic sequencing methods to determine how the microbiome is affected by the active metabolism of these organisms. 

Person specification   

A person with a degree in Microbiology or related discipline is required.  Experience with field work is desirable.  This project offers the opportunity to live and study at Aarhus univerisity for up to a year.   

For more information on the supervisor for this project, please visit the UEA website

The start date is October 2023.

Funding Notes

This project has been shortlisted for funding by the ARIES NERC DTP. Successful candidates will be awarded a NERC studentship, which covers fees, stipend (£17,668 for 2022/23) and funding to support the doctoral research. Excellent applicants from quantitative disciplines may be considered for an additional three months’ studentship funding.
Unfortunately, no additional funding is available to assist with relocation or visa costs.
ARIES encourages applications from all, regardless of gender, ethnicity, disability, age, or sexual orientation. Academic qualifications are considered alongside relevant non-academic experience.
For further information, please visit


1 On the evolution and physiology of cable bacteria.
Kjeldsen KU et al. Proc Natl Acad Sci U S A. (2019) 116:19116-19125

2 Bacteria are important dimethylsulfoniopropionate producers in coastal sediments
Williams, B. T et al. Nature Microbiology. (2019) 4, p.1815-1825

3 Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria
Edwards MJ et al. (2020)
Protein Sci. 2019. doi: 10.1002/pro.3787
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