Dr Melinda Mayer

Senior Researcher

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Translational microbiome

My main research interest is studying mechanisms of combating pathogens involved in gut health and food spoilage. My scientific training was originally in Botany, with degrees from the Universities of Bristol and Durham and postdoctoral positions studying plant reactions to infection, the engineering of plant secondary metabolism and the manipulation of plant polyamine levels. Since 2004 I have been working in the Narbad group and my research has focused on searching for novel antimicrobials and mechanisms to control clostridial pathogens.

I am currently investigating the probiotic bacterium Lactobacillus johnsonii FI9785, looking at exopolysaccharide (EPS) biosynthesis and surface proteins, and investigating the effect of variants and mutants on aggregation and adhesion. We are interested in understanding the mechanism of competitive exclusion and whether surface characteristics play a role in the ability of Lactobacillus johnsonii to exclude pathogens in poultry. Recent research has elucidated the structure and function of its EPS layer, studied its ability to reduce colonisation of pathogens and demonstrated its utility as a continuous delivery system for antimicrobials.

I am also building on previous work on the discovery and application of bacteriophages and their cell lytic endolysins for the control of the important human gut pathogen Clostridium difficile, the food poisoning pathogen C. perfringens and the food spoilage organisms C. tyrobutyricum and C. sporogenes. A collaboration with EMBL, Hamburg is allowing us to investigate endolysin structure and use the information to improve enzyme activity, and with a group at INIA, Madrid we are exploring the use of endolysins and bacteriophages to detect and combat Clostridia in cheese.

In addition to my own research I am involved in a variety of projects with students and visiting workers, including the discovery and application of antimicrobials (lantibiotics with Teagasc, nanoparticles with Procarta), probiotic bacteria (IPLA, Asturias) and investigation of bacteria involved in Nigerian fermented cereals (with the University of Lagos).

I am the institute’s Equality and Diversity champion and am also a member of the Athena Swan committee and the EU working group committee.

Key Publications

Dunne, M., Leicht, S., Krichel, B., Mertens, H. D., Thompson, A., Krijgsveld, J., Svergun, D. I., Gomez-Torres, N., Garde, S., Uetrecht, C., Narbad, A., Mayer, M. J., and Meijers, R. (2016) Crystal structure of the CTP1L endolysin reveals how its activity is regulated by a secondary translation product. J Biol Chem 291, 4882-4893

Gervasi, T., Horn, N., Wegmann, U., Dugo, G., Narbad, A., and Mayer, M. J. (2014) Expression and delivery of an endolysin to combat Clostridium perfringens. Applied Microbiology and Biotechnology 98, 2495-2505

Meader, E., Mayer, M. J., Steverding, D., Carding, S. R., and Narbad, A. (2013) Evaluation of bacteriophage therapy to control Clostridium difficile and toxin production in an in vitro human colon model system. Anaerobe 22, 25-30

Hatziioanou, D., Mayer, M. J., Duncan, S. H., Flint, H. J., and Narbad, A. (2013) A representative of the dominant human colonic Firmicutes, Roseburia faecis M72/1, forms a novel bacteriocin-like substance. Anaerobe 23, 5-8

Dertli, E., Colqhoun, I. J.,Gunning, A. P., Bongaerts, R. J., Le Gall, G., Bonev, B. B., Mayer, M. J., and Narbad, A. (2013) Structure and biosynthesis of two exopolysaccharides produced by Lactobacillus johnsonii FI9785. J Biol Chem 288, 31938-31951

Diaz M., Kellingray L., Akinyemi N., Adefiranye O., Olaonipekun A. B., Bayili G. R., Ibezim J., Plessis A., Houngbédji M., Kamya D., Mukisa I. M., Mulaw G., Manthi Josiah S., Chienjo W. O., Atter A., Agbemafle E., Annan T., Bernice Ackah N., Buys E., Hounhouigan D. J., Muyanja C., Nakavuma J., Odeny D. A., Sawadogo-Lingani H., Tefera A. T., Amoa-Awua W., Obodai M., Mayer M. M., Oguntoyinbo F. A., Narbad A.. (2019)

Comparison of the microbial composition of African fermented foods using amplicon sequencing

Scientific Reports, 9, 13863

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Erickson A. K., Jesudhasan P. R., Mayer M. J., Narbad A., Winter S. E., Pfeiffer J. K.. (2018)

Bacteria facilitate viral co-infection of mammalian cells and promote genetic recombination

Cell Host and Microbe, 23, 77-88

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Garcia Gutierrez E., Mayer M. J., Cotter P. D., Narbad A.. (2018)

Gut microbiota as a source of novel antimicrobials

Gut microbes

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Gomez-Torres N., Dunne M., Garde S., Meijers R., Narbad A., Avila M., Mayer M. J.. (2018)

Development of a specific fluorescent phage endolysin for in situ detection of Clostridium species associated with cheese spoilage.

Microbial biotechnology, 11, 332-345

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Diaz M., Wegmann U., Akinyemi N., Oguntoyinbo F., Sayavedra L., Mayer M. J., Narbad A.. (2018)

Complete Genome Sequence of Ochrobactrum haematophilum FI11154, Isolated from Kunu-Zaki, a Nigerian Millet-Based Fermented Food.

Genome announcements, 6

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Gherghisan-Filip C., Saalbach G., Hatziioanou D., Narbad A., Mayer M. J.. (2018)

Processing and Structure of the Lantibiotic Peptide Nso From the Human Gut Bacterium Blautia obeum A2-162 analysed by Mass Spectrometry.

Scientific reports, 8, 10077

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Diaz M., Wegmann U., Akinyemi N., Oguntoyinbo F. A., Sayavedra L., Mayer M., Narbad A.. (2018)

Complete Genome Sequence of Ochrobactrum haematophilum FI11154, Isolated from Kunu-Zaki, a Nigerian Millet-Based Fermented Food.

Genome announcements, 6

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