Andrew Johnston

Professor

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Personal profile

Administrative Posts

  • Module organiser for Year 2 module “Microbiology” (2B28)
  • Associate Dean Research in the Science Faculty at UEA
  • Member of the University Honorary Degrees Committee
  • Member of the University Senate Disciplinary Committee

Career

  • 1970 BSc "Genetics", University of Edinburgh
  • 1973 PhD University of Edinburgh
  • 1973 – 1989 Research Scientist at John Innes Institute, Norwich, UK
  • 1989 – present Professor Biological Sciences, University of East Anglia, Norwich, UK
     

ResearcherID 
http://www.researcherid.com/rid/D-1859-2009

External Activities

  • Co-organizer Society General Microbiology Meeting on Metagenomics, April 2006.
  • Member Steering Committee European Nitrogen Fixation Conference
  • Member of NERC Peer Review College

Key Research Interests and Expertise

I am a microbial geneticist, with interests in the ways that bacteria undertake biotransformations that relate to biogeochemical cycling and in the ways that these organisms regulate these processes in response to external factors. 

Current Research Projects

  • Identification of the ways in which bacteria catabolise the anti-stress molecule dimethylsulfoniopropionate that is made by many marine phytoplankton and whose breakdown by microbes represents a major step in the global sulfur cycle.
  • Analysis of metal-responsive gene regulation in Rhizobium and in marine alpha-proteobacteria.

Life in our research group

We have used genetics set to determine how microbes catabolise dimethylsulfoniopropionate (DMSP), a hugely abundant anti-stress molecule made by marine plankton, some seaweeds and a very few land plants. These studies identified a remarkable array of totally different ways in which different lineages of microbes break down DMSP. Some of these release the gaseous by-product dimethyl sulfide (DMS) which itself is environmentally influential – it is a potent chemo-attractant for marine animals and its oxidation products are “cloud condensation nuclei” that initiate cloud formation over the oceans. The “ddd” genes that are involved in DMS production are prone to rampant horizontal gene transfer, and have been transferred, at least once, between marine bacteria and various fungi. Their regulation also has interesting and unusual features. By examining the distribution of the ddd genes in individual genomes and in metagenomic data sets, we can deduce their abundance in different microbial lineages and in different environments, with implications on the eco-physiology of this important step in the global sulfur cycle. Our field work takes us to the far north of Norfolk, where we sample the salt marshes, the beaches and the occasional fish shop for interesting bacteria and fungi. 

Although transition metals such as iron and manganese are important in the nutrition of bacteria in the seas, little is known of the ways in these are acquired or the ways in which the uptake genes are regulated. In a new programme, we use genetics and genomics to address these topics. This builds on earlier studies on the iron-regulon of the Rhizobia a group of bacteria that induce nitrogen-fixing nodules on legume plants. These bacteria use two global regulators, called Irr and RirA, which are very different from the conventional Fur global regulator, which represses many genes in many other bacteria, including the model species Bacillus subtilis and Escherichia coli. Working in concert, Irr is a heme-binding polypeptide that represses many genes under conditions of iron shortage - in contrast, the FeS-containing regulator RirA represses a different suite of genes under conditions where iron is in short supply.
Our work is much aided by productive collaborations with colleagues in Norwich (Nick Le Brun, Charles Brearley, Tony Davy, Phil Page, Phil Poole, Arnoud van Vliet, Yohan Chan, Allan Downie and Paul Nicholson) and elsewhere (such as Chris Dupont, Krystal Rypien, Michael Steinke, Dmitry Rodionov, Steve Giovanonni, Colin Murrell and Hendrik Schaefer).

PhD Positions

Click here for current PhD opportunities in Biological Sciences. But feel free to email me to discuss projects outside these areas and alternative sources of funding.

Postdocs & fellows

  • Dr Andrew RJ Curson
  • Dr Jonathan D Todd (part-time)
  • Mark Kirkwood (PhD Student)
  • Emily Fowler (PhD student)
  • Rob Green (PhD Student, with Arnoud van Vliet, Institute of Food Research)

 

Areas of Expertise

Microbiology; plant disease; nitrogen fixation; bacterial genetics; microbial uptake and utilisation of iron; marine molecular biology, in particular the molecular genetics of sulphur cycling in the seas.

Teaching Interests

  • Module organiser for Year 2 module “Microbiology” (2B28)
  • Lecturer in Year 1 Module “Fundamentals of Molecular Biology and Genetics” (1A13)
  • Lecturer in Year 2 Module “Genetics/Clinical Genetics” (2B17/19)
  • Lecturer in Year 3 Module “Microbial Cell Biology” (3C10)
  • Lecturer in Year 3 Module “Organisms and Environment” (3C45)
  • Seminar leader in Year 1 Module “Skill for Biologists” (1A4Y)