Diatom-bacteria interactions: deciphering impacts on algal bloom regulation and toxicity


Diatom-bacteria interactions: deciphering impacts on algal bloom regulation and toxicity


Project Description

Dr Katherine Helliwell (Marine Biological Association of the UK)

Dr Michael Cunliffe (Marine Biological Association of the UK, University of Plymouth)

Prof Willie Wilson (Marine Biological Association of the UK)

Scientific background

Marine phytoplankton are vital in regulating our global climate, contributing almost half of the biosphere’s net primary production. Diatoms are one of the most important phytoplankton groups, generating as much organic carbon as all terrestrial rainforests combined. Diatoms form spatially extensive blooms that exert global-scale influences on biogeochemical cycles and underpin ecosystems. Due to the release of harmful toxins, some diatom blooms can also have a negative impact on marine ecosystems and fisheries.

The biotic interactions of diatoms with predators, parasites, competitors and symbionts, can profoundly influence natural diatom populations, and are an important factor regulating bloom dynamics and potential toxicity. Despite the clear importance of such interactions for diatom ecology and marine ecosystem functioning, little is known about the mechanisms diatoms employ to i) recognise and respond to other microbes, or ii) regulate production of harmful toxins. These represents important knowledge gaps that need to be addressed, in order to better understand factors governing diatom bloom formation and toxicity.

Research methodology

This PhD will couple field sampling at the Western Channel Observatory coastal Station L4, which has regular diatom blooms, with state-of-the-art cell biological approaches in the laboratory. Field sampling will enable isolation of diatom-bloom associated microbes that will be brought into the laboratory for further experimentation. A combination of physiological (co-culturing), metabolomics and molecular approaches will be employed to examine the nature of such interactions, and their impact on diatom toxicity. A key aim will be to identify and characterise signalling pathways employed by diatoms to recognise and respond to their neighbours using live-cell imaging and CRISPR-Cas9 gene editing.


The successful candidate with gain training in cutting-edge cell and molecular biology approaches including live-cell imaging (e.g. confocal microscopy), CRISPR-Cas9 gene knock-out, genetic transformation, bioinformatics, and cloning, alongside microbial physiology and environmental microbiology techniques. Professional development, including training in core verbal and written communication, research and analytical skills will also be provided.

Person specification

An enthusiastic, motivated individual interested in how molecular mechanisms in the cell impact ecosystem level processes, with a relevant biological sciences degree (marine biology, microbiology, plant sciences).

The successful candidate will be registered for a PhD in the University of Plymouth’s School of Biological and Marine Sciences, part of the Marine Institute.


  • Helliwell K. E., Pandhal J., Cooper M, Longworth J., Kudahl U., Russo D., Tomsett E., Bunbury F., Salmon D., Smirnoff N., Wright P., and Smith A. G., (2018). Quantitative proteomics of a B12‐dependent alga grown in coculture with bacteria reveals metabolic tradeoffs required for mutualism. New Phytologist. 217(2): 599-612.
  • Kazamia E., Helliwell K. E., Smith A. G. (2016). How mutualisms arise in phytoplankton communities: building eco-evolutionary principles for aquatic microbes. Ecology Letters. 19(7):810-822
  • Helliwell K. E., Chrachri A., Taylor A., Koester J., Wharam S., Wheeler G., and Brownlee C. Novel classes of voltage-gated Na+ and Ca2+ channels play important signalling roles in unicellular eukaryotes. In review.
  • Taylor JD, Cottingham SD, Billinge J & Cunliffe M (2014) Seasonal microbial community dynamics correlate with phytoplankton-derived polysaccharides in surface coastal waters. The ISME Journal 8: 245–248.
  • Taylor JD & Cunliffe M (2017) Coastal bacterioplankton community response to diatom-derived polysaccharide microgels. Environmental Microbiology Reports 9: 151–157

Open for applications

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