An amoeba phagocytosis model reveals a novel developmental switch in the insect pathogen Bacillus thuringiensis


Beeton, M.L., Atkinson, D.J. and Waterfield, N.R., 2013. An amoeba phagocytosis model reveals a novel developmental switch in the insect pathogen Bacillus thuringiensis. Journal of Insect Physiology, 59 (2), pp. 223-231.

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    The Bacillus cereus group bacteria contain pathogens of economic and medical importance. From security and health perspectives, the lethal mammalian pathogen Bacillus anthracis remains a serious threat. In addition the potent insect pathogen Bacillus thuringiensis is extensively used as a biological control agent for insect pests. This relies upon the industrial scale induction of bacterial spore formation with the associated production of orally toxic Cry-toxins. Understanding the ecology and potential alternative developmental fates of these bacteria is therefore important. Here we describe the use of an amoeba host model to investigate the influence of environmental bactivorous protists on both spores and vegetative cells of these pathogens. We demonstrate that the bacteria can respond to different densities of amoeba by adopting different behaviours and developmental fates. We show that spores will germinate in response to factors excreted by the amoeba, and that the bacteria can grow and reproduce on these factors. We show that in low densities of amoeba, that the bacteria will seek to colonise the surface of the amoeba as micro-colonies, resisting phagocytosis. At high amoeba densities, the bacteria change morphology into long filaments and macroscopic rope-like structures which cannot be ingested due to size exclusion. We suggest these developmental fates are likely to be important both in the ecology of these bacteria and also during animal host colonisation and immune evasion.


    Item Type Articles
    CreatorsBeeton, M.L., Atkinson, D.J. and Waterfield, N.R.
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    DepartmentsFaculty of Science > Biology & Biochemistry
    Publisher StatementWaterfield_Journal_Insect_Physiol_2012.pdf: NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Insect Physiology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Insect Physiology, vol 59, issue 2, 2013, DOI 10.1016/j.jinsphys.2012.06.011
    ID Code31161


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