Testing the effects of prey surface changes on Bdellovibrio bacteriovorus predation

Lai, Ting (2019) Testing the effects of prey surface changes on Bdellovibrio bacteriovorus predation. MRes thesis, University of Nottingham.

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Abstract

Bdellovibrio bacteriovorus is an invasive bacterial predator of a wide range of Gram negative bacteria including many ESKAPE pathogens. It attaches to the outer membrane of the prey cell and invades into the periplasm of prey cells, ultimately killing the cell from the inside. The target for prey recognition on the outer membrane is currently unknown. B. bacteriovorus is predatory both in vitro and in vivo in zebrafish for several of these pathogens. However, some pathogens are known to adapt their membrane composition when stressed by host or other different environments. One such pathogen is Acinetobacter baumannii.

A. baumannii is frequently found to be multidrug resistant where resistance has developed to the drugs of last resorts namely the carbapenem and polymyxin classes of antibiotics. One way that A. baumannii does this is via the loss of lipooligosaccharide (LOS) from the outer membrane. LOS is a form of lipopolysaccharide (LPS) but without the O-antigen and a modified core oligosaccharide.

In a first part of the project, strains of A. baumannii with known outer membrane modifications from published work of the Trent lab were tested for changes in predation by B. bacteriovorus. It was previously hypothesised that the Lipid A component of LPS was a target for Bdellovibrio attachment, but surprisingly this work shows no significant change in predation in these LOS deficient mutants. These data therefore disproves Lipid A or the core oligosaccharide as the target for predation; future work should look at other conserved components on the Gram negative surface.

In the second part, in vivo studies in zebrafish were done via microinjection of a clinical strain of A. baumannii 11W359501 into the hindbrain. Previous work found that there was no B. bacteriovorus predation in vivo but occured in vitro. Therefore, tests for cell surface adaptation by the pathogen were undertaken, with RNA sequencing from samples of A. baumannii 11W359501 pre- and post-adaptation in host. Analysis of these RNA-seq data has elucidated the upregulation of genes encoding a potential type VI secretion system mechanism which may be responsible for killing B. bacteriovorus in vivo, abrogating its predatory effects. Future work could check the involvement of this system and further experiments are suggested.

Item Type: Thesis (University of Nottingham only) (MRes)
Supervisors: Sockett, R.E.
Tyson, Jess
Keywords: Bdellovibrio bacteriovorus; Prey recognition; Acinetobacter baumannii; Predation
Subjects: Q Science > QR Microbiology > QR 75 Bacteria. Cyanobacteria
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 59480
Depositing User: Lai, Ting
Date Deposited: 26 Apr 2022 09:43
Last Modified: 26 Apr 2022 09:44
URI: http://eprints.nottingham.ac.uk/id/eprint/59480

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