Imperial College London


Faculty of MedicineDepartment of Infectious Disease

Research Associate



+44 (0)20 7594 3058alexander.webb1




Sir Alexander Fleming BuildingSouth Kensington Campus





During my Doctoral training at King's College London my research focused on the role of ATP-binding cassette (ABC) transporters in the physiology of Streptococcus mutans. This organism was originally isolated from carious lesions of the tooth. Using physiological and molecular studies I was able to: identify and characterise an ABC transporter (RnsBACD) involved in the uptake of ribonucleosides; identify and characterise an ABC transporter (MalXFGK) involved in the uptake of maltotriose and longer maltodextrins; further clarify the subtrates taken up by the previously characterised ABC transporter MsmEFGK; show that ABC-ATPases MalK and MsmK are interchangeable and can energise both the Msm and Mal transport systems; identify and characterise the principle phospoenolpyruvate-dependent phosphotransferase maltose system (MalT).

Previous postdoctoral projects include:

designing padlock probes (molecular inversion probes) for the identification of different Brucellae (in the group of Dr Sally J. Cutler).

identification and characterisation of two-enzymes system for glycolipid and polyglycerolphosphate lipoteichoic acid synthesis in the Gram-positive pathogen Listeria monocytogenes (in the group of Prof. Angelika Gründling).


Current research:

I am currenlty using synthetic biology to build affordable and molecular cell-based biosensors as generic platforms that can be applied to quickly and easily detect parasites via their protease signatures.

The parasitic infection Schistosomiasis affects over 200 million people worldwide, with estimates suggesting that a further 780 million people are at risk of infection. The causative agents are fluke worms of the Schistosoma genus, and infection only occurs when the cercarial larvae are able to penetrate the skin. To facilitate this, the cercariae secrete an elastase possessing defined substrate specificity. As a proof of concept, my project takes advantage of this property of the cercarial elastase, and has used it to design and create biosensors that are specific in targeting Schistosoma. The design of the biosensors is based on a two-pronged approach, 1) an accurate detection system which is targeted to the cercarial elastase, and 2) an easily measurable output. Using synthetic biology approaches we have engineered the biosensors to be “housed” in two bacterial chassis, Bacillus subtilis and Escherichia coli, and we have further designs that will enable for a cell-free based biosensor.



Kelwick RJR, Webb AJ, Wang Y, et al., 2021, AL-PHA beads: bioplastic-based protease biosensors for global health applications, Materials Today, ISSN:1369-7021, Pages:1-1

Kelwick R, Webb A, Freemont P, 2020, Biological materials: the next frontier for cell-free synthetic biology, Frontiers in Bioengineering and Biotechnology, Vol:8, ISSN:2296-4185

Braun L, Hazell L, Webb AJ, et al., 2020, Determining the viability of Schistosoma mansoni cercariae using fluorescence assays: an application for water treatment, Plos Neglected Tropical Diseases, Vol:14, ISSN:1935-2727

Kelwick RJR, Ricci L, Chee SM, et al., 2019, Cell-free prototyping strategies for enhancing the sustainable production of polyhydroxyalkanoates bioplastics, Synthetic Biology, Vol:3, ISSN:2397-7000


Webb AJ, Kelwick R, Wang Y, et al., 2019, AL-PHA beads: bioplastic-bsaed protease biosensors for global health, British Society for Parasitology Autumn Symposium, Belfast, UK

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