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

Lead Research Organisation: Royal Holloway, University of London
Department Name: Biological Sciences

Abstract

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.

Publications

10 25 50

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 We have found out that models of social conflicts, cheating cooperation etc, can be particularly informative for understanding the virulence of parasites, as investment in microbial virulence can often be seen as a joint cooperative venture.
This key understanding has diverse implications for how we might be able to manipulate virulence, particularly for biological control agents, as well as how strategies to suppress microbial virulence might affect the long-term evolutionary trajectory of parasites.
Exploitation Route Currently we are exploring ways of taking these findings forward in terms of improving biological control agents. This has led to a funded Leverhulme grant award in which we are applying the principles of social evolution / group selection to select for improved killing power in microbial control agents. We have been applying these methods to develop bacterial strains that can overcome resistance in a target pest. This has proved to be highly successfull with gains in killing power of new mutants in excess of 100x. Currently we are exploring options for protecting some of the intellectual property associated with these methods.
Sectors Agriculture, Food and Drink,Environment,Healthcare,Pharmaceuticals and Medical Biotechnology

 
Description This research has revealed a great deal about the maintenance of virulence in bacteria and biological control agents. While this has not had an immediate impact yet, this award has informed future proposals on biological pesticide improvement (see Leverhume RPG-1014-252) and may yet have an impact on virulence management. Further collaborations have now established that a social evolution may be important for understanding the stability of virulence in entomopathogenic nematodes. We anticipate that these results may have relevance and impact in how researchers and industry bodies attempt to culture and improve their biocontrol agents. We have now submitted a patent application (founded on the principles established in this fellowship) and have attracted funding for a PhD studentship to apply social evolution theory to the improvement of fungal entomopathogens.
First Year Of Impact 2014
Sector Agriculture, Food and Drink,Creative Economy
Impact Types Economic

 
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 Public
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 Leverhulme Standard grant
Amount £233,233 (GBP)
Funding ID RPG-2014-252 
Organisation The Leverhulme Trust 
Sector Academic/University
Country United Kingdom
Start 01/2015 
End 12/2018
 
Title Stable red/green marker plasmids 
Description We have engineered stable marker plasmids for Bacillus thuringiensis / B. cereus that express RFP or GFP as well as distinct antibiotic resistance plasmids. These are particularly useful for carrying out competition experiments or exploring the ecology and function of these bacteria in containment. 
Type Of Material Technology assay or reagent 
Year Produced 2016 
Provided To Others? Yes  
Impact see Zhou et al 2014 Curr Biol 
 
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 Social biology of virulence in entomopathogenic nematodes 
Organisation U.S. Department of Agriculture USDA
Department Agricultural Research Service
Country United States 
Sector Public 
PI Contribution I developed and designed experiments that would investigate the problem of unstable virulence in entomopathogenic nematodes. I have then analysed the data coming out of these experiments
Collaborator Contribution My partner (David Shapiro-Ilan) and his laboratory carried out the selection experiments.
Impact We have identified a major possible cause of the loss of virulence in these important biocontrol agents. We expect this to have real implications for how industry and researchers maintain effective populations of nematodes. This work has now resulted in a publication Shapiro-Ilan & Raymond (2016)
Start Year 2012
 
Description The evolutionary ecology of quorum sensing in vivo 
Organisation French National Institute of Agricultural Research
Department INRA Versailles
Country France 
Sector Public 
PI Contribution We have brought ecological and evolutionary perspectives to the understanding of the function of quorum-sensing during in vivo infections. Our contribution has included many experiments exploring the fitness of diverse mutants and examining the distribution and structure of early stage Bacillus infections.
Collaborator Contribution Our partners contributed important genetic tools (an array of mutants), technical expertise and training for one of my PhD students.
Impact Thus far the collaboration has resulted in one high impact publication (Zhou et al 2014, Curr Biol) and we have another manuscript in preparation. We also have a joint grant proposal in review. The colloboration is multidisciplinary and involves molecular biologists, geneticists and evolutionary ecologists.
Start Year 2011
 
Description Wuhan plasmid project 
Organisation Huazhong Agricultural University
Department State Key Laboratory of Agricultural Microbiology
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
 
Title BIOPESTICIDES 
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
URL http://www.ibma-global.org/en/news/ibma-and-copa-cogeca-workshop-to-explore-the-implications-of-baci...
 
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
URL http://www.abim.ch
 
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 Presentation of results to biological control community 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I gave a plenary talk at an international organization of biological control meeting, which is attended by practitioners, biocontrol companies as well as academics.

This led to the collaboration with a USDA lab on entomopathogenic nematode virulence.
Year(s) Of Engagement Activity 2010
 
Description Pursuing industrial collaborators for biopesticide development 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact This has led to the submission of a BBRSR industrial partnership award project with Syngenta, which unfortunately was not funded. More recent applications have attracted expressions of interest or informal support from Dow Agroscience.

As yet impacts are unknown, but we have developed a wider network of contacts in industry that might help us commercialize any future research findings.
Year(s) Of Engagement Activity 2009,2011,2012,2013,2014
 
Description Silwood Bugs Day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Industry/Business
Results and Impact 100-200 members of the public attended a Silwood Park open day focussed on entomological research at Imperial. As well as academic staff local research organizations, charities and conservation organizations had stands. The local MP and councillors also attended.
Year(s) Of Engagement Activity 2015
 
Description Visit and planning meeting with biopesticide producers 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Attended meeting at eNema HQ in Kiel, Germany. eNema are one of the largest producers of biopesticides in the EU. We discussed my recent results with nematodes and Bacillus and agreed to collaborate on a BBSRC proposal investigating nematode improvement for corn rootworm pests.
Year(s) Of Engagement Activity 2015
 
Description Workshop meeting with CABI 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Third sector organisations
Results and Impact 5-6 members of staff from Silwood Park attended a workshop run by CABI, a leading international biological control organization based in Egham. The purpose of the meeting was to explore future avenues for collaboration between academia and the needs of this sector.
Year(s) Of Engagement Activity 2015
 
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