Intra- and inter-specific competition and the evolution of cooperation in Bacillus thuringiensis

Lead Research Organisation: University of Oxford
Department Name: Zoology


Cooperation is a common feature of bacterial lifestyles. This may be particularly true of bacteria that cause diseases (pathogenic bacteria) and of beneficial bacteria that live in close association with larger hosts (symbiotic bacteria). Many of the essential tools that enable bacteria to exploit hosts are based on what can be called 'public goods'. These are enzymes or toxins and other compounds that bacteria must export outside the cell in order to break open host cells and harvest the resources. Bacteria also export chemical signals that communicate information about their abundance within hosts to other bacteria and may thereby coordinate attack. Efficient use of hosts therefore requires bacteria to act collectively, if a low proportion of bacteria fail to cooperate bacterial infections should to be less successful and produce fewer infections in new hosts. These public goods are expensive to make in terms of resources. In evolutionary terms cooperation can be unstable because bacteria may leave more offspring within hosts if they 'cheat' and fail to contribute to these expensive cooperative products. Evolutionary theory has made predictions about how cooperation could be maintained. If most infections are established by close relatives with similar strategies, metabolically expensive cooperation will benefit their relative and they, in turn will then spread the genes for cooperation. In addition, while competition within hosts can lead to selection for cheating, competition between groups of bacteria inhabiting different hosts will select for groups that exploit their host more efficiently, and which therefore cooperate. The evolutionary forces that can maintain cooperation between hosts and symbiotic bacteria are diverse. However, one possible mechanism is that host can discriminate between bacteria that are exploitative or not and produce increased immune responses against symbionts that are not cooperative. I propose to test these evolutionary ideas on cooperation, in relation to the production of toxins, antibiotics and chemical signals. Prelimary data also indicate that the exploitation of hosts by Bt is strongly affect by competition with symbionts such as P. agglomerans. I will test how competition with symbionts affects the expression of cooperative toxins. Conversely, these symbionts can cooperate with Bt rather than continue to cooperate with hosts as gut symbionts. I will test how host insects react to infections with 'cheating' symbionts. I will use a study system which is familiar to me and also of environmental and medical importance. This system is the insect-killing bacteria Baccillus thuringiensis, a caterpillar host (the larvae of the diamondback moth) and the gut symbiont Pantoea agglomerans. B. thuringiensis (Bt) is used as a biological pesticide. It is applied against pests in horticulture, forestry and fruit productionan and against mosquito larvae. It has an excellent safety record, it does not harm humans, animals or beneficial insect predators and is licensed as an organic spray. While Bt pesticides are efficient at killing pests they are relatively poor at being transmitted as a disease from pest to pest after spraying. Improved transmission would have many benefits for the ability of Bt to control pests. Preliminary data in my laboratory suggests that cooperative traits are vital for efficient transmission between hosts, as the above theory predicts. An understanding of how cooperation maintains efficient transmission and transmission maintains cooperation could therefore be vital to understanding how to improve its use. Bt is closely related to the bacteria that causes anthrax, Bacillus anthracis and to Bacillus cereus, several strains of which cause food-poisoning in humans. These human pathogens use very similar biochemical machinery to Bt and a understanding of how these bacteria cooperate to exploit hosts may eventually be of medical significance.


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Related Projects

Project Reference Relationship Related To Start End Award Value
NE/E012671/1 30/10/2007 29/11/2009 £498,804
NE/E012671/2 Transfer NE/E012671/1 01/11/2009 31/07/2013 £307,631
Description see entry to NE/E012671/2
NE/E012671/1 simply refers to the first two years of this fellowship at Oxford.
Exploitation Route see entry to NE/E012671/2
NE/E012671/1 simply refers to the first two years of this fellowship at Oxford.
Sectors Agriculture, Food and Drink,Creative Economy,Healthcare,Pharmaceuticals and Medical Biotechnology

Description Advising stakeholders & EU commission on biosafety of microbial pesticides
Geographic Reach Europe 
Policy Influence Type Gave evidence to a government review
Impact Certain EU members states have been agitating for tightening up the regulations on the application of microbial bicontrol agents in particular Bacillus thuringiensis (Bt). This position was in part driven by misconstruing the basis of some food poisoning incidents in Germany. I presented evidence to industry and to a meeting involving regulators, scientists and stakeholders. My evidence and analysis confirms the excellent safety record of Bt and unpicked the very poor evidence linking Bt to food poisoing or other disease. Following this consultation the EU have not taken the decision to tighten up regulations, a decision that faciltates the use of environmentally friendly biological alternatives to chemical insecticides. My responses to the European Food Safety Authority on the biological safety of Bt have been published in FEMS Microbiology and Ecology.
Description Membership of ACRE- DEFRA committee on release of GMOs and biological control agents
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
Description AHDB studentship scheme
Amount £71,400 (GBP)
Organisation Agricultural and Horticulture Development Board 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2018 
End 09/2021
Description Group selection as a novel tool to screen and improve biological pesticides
Amount £371,386 (GBP)
Funding ID BB/S002928/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 12/2018 
End 11/2021
Description Industrial Partnership - (as part of BBSRC IPA award) 
Organisation Dow AgroSiences
Country United Kingdom 
Sector Private 
PI Contribution My team will be engaged in producing mutants with increased virulence to resistant insect pests, as well as screening strain collections and toxin libraries for novel or improved isolates and proteins.
Collaborator Contribution The partner will be providing access to a sequenced strain collection as welll as to additional sequencing / molecular characaterization services.
Impact not yet....project began end of Feb 2019
Start Year 2019
Description Wuhan plasmid project 
Organisation Huazhong Agricultural University
Department State Key Laboratory of Agricultural Microbiology
Country China 
Sector Academic/University 
PI Contribution Shaped research questions, wrote paper, shaped and informed analysis
Collaborator Contribution Collected genomic data, analysed data, co-wrote paper
Impact This has resulted in a publication in mBio (Zheng et al)- and is a collaboration between molecular biologists and myself as an evolutionary ecologists. Other projects related to this collaboration are still ongoing.
Start Year 2016
Description The present invention relates to Bacillus thuringiensis strains which are phenotypically stable and have increased virulence compared to the wild-type strains, whereby the increased virulence has been achieved by the exposure of the strain to a mutagen during one or more passages. Such strains are particularly useful as biopesticides. Methods for increasing virulence in microbial pesticides are also described. 
IP Reference WO2019030529 
Protection Patent application published
Year Protection Granted 2019
Licensed No
Impact This application has helped us in negotiations with commercial companies including Dow Agroscience and Bayer.
Description IBMA Copa-Cogeca workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Safety and regulation of Bt based biopesticides were discussed with stakeholders and presented to representatives of EU commission
Year(s) Of Engagement Activity 2017
Description IBMA industry conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact This is the international biocontrol manufacturers annual meeting and very much an industry meeting rather than an academic conference. I was invited to give a talk on the safety on micro-organisms in biocontrol
Year(s) Of Engagement Activity 2017
Description Open days 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Undergraduate students
Results and Impact The Penryn campus runs a series of open days throughtout the year designed to engage with prospective students and their families. This gives us a venue in which to talk about our research generally and that of the campus. In an event last summer, for instance, I discussed the recent invasion of diamond back moth and met with a local cabbage farmer and talked about pest control issues associated with this species.
Year(s) Of Engagement Activity 2016,2017,2018
Description invited research application - Bayer 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact My research group was invited to pitch for research funding from Bayer in order to pursue research avenues following on from work on evoltuion of virulence in microbial insecticides. This involved preliminary meetings, a Skype presentation to the company and the submission of a research proposal. This proposal is still under consideration, and was submitted late last year.
Year(s) Of Engagement Activity 2018