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Cooperative heavy-metal detoxification by P. aeruginosa. Siobhán O ’ Brien, Adela Luján & Angus Buckling College of Life and Environmental Sciences, University of Exeter Cornwall Campus, UK Email: s.obrien@exeter.ac.uk. Siderophore production: A model system for studying cooperation. Fe2+.
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Cooperative heavy-metal detoxification by P. aeruginosa Siobhán O’Brien, Adela Luján & Angus Buckling College of Life and Environmental Sciences,University of Exeter Cornwall Campus, UK Email: s.obrien@exeter.ac.uk
Siderophore production: A model system for studying cooperation Fe2+ West SA & Buckling A. 2003 Proc.R.Soc.Lond.B 270:37 – 44. Griffin AS et al. Nature. 430 :1024 – 1027 West SA et al 2007 Annu. Rev. Ecol. Evol.Syst.38:53 – 77 Braud et al. 2010. Environ Microbiol. 2: 419 – 425 Microbial communities- Cambridge
Our Questions Part 1 Part 2 Part 3 Microbial communities- Cambridge
How do we determine if a behaviour is altruistic? There is a benefit to the recipient Do cooperators outcompete cheats when grown alone? The behaviour itself is costly Do cheats outcompete cooperators in competition? WT WT Ch Ch WT WT Ch WT WT WT Ch Ch Ch WT Microbial communities- Cambridge
Is heavy metal detoxification by siderophores a cooperative trait? Wt Ch 1:1 (X12) 6mM CuSO4 Strains: Wt: PAO1 Ch:PAO1ΔPvdΔPch Copper Sulfate Cheat Cooperator Microbial communities- Cambridge
Is heavy metal detoxification by siderophores a cooperative trait? Do cooperators do better than cheats when grown alone in toxic environments? ✔ Do cheats outcompete cooperators in competition in toxic environments? ✔ Cheat relative fitness ~ metal treatment: conditions: F1,89 =207.89, p < 0.001) O’Brien, Hodgson & Buckling. Social Evolution of toxic Metal Bioremediation in P. aeruginosa. 2014.Proc.R.Soc.Lond.B 281(1787) Microbial communities- Cambridge
Is heavy metal detoxification by siderophores a cooperative trait? Experimental evolution (approx. 105 generations) WT WT X12 Copper Iron Frequency of cheats Total siderophore (pyoverdine) production Microbial communities- Cambridge
Is heavy metal detoxification by siderophores a cooperative trait? Conclusion: Copper detoxification is a social trait that actively selects for the evolution of social “cheats”. *** *** O’Brien, Hodgson & Buckling. Social Evolution of toxic Metal Bioremediation in P. aeruginosa. 2014.Proc.R.Soc.Lond.B 281(1787) Microbial communities- Cambridge
Our Questions Part 1 Part 2 Part 3 Microbial communities- Cambridge
How is cheat fitness affected by the presence of the soil microbial community? Cheat (species 2) Cooperator (species 1) Microbial communities- Cambridge
How is cheat fitness affected by the presence of the soil microbial community? Microbial communities- Cambridge
How is cheat fitness affected by the presence of the soil microbial community? Monoculture Co-culture Cheat relative fitness (w) Cheat relative fitness (w) +Cu +Cu +Cu +Cu -Comm. + Comm. - Comm. + Comm. -Comm. + Comm. - Comm. + Comm. (cheat fitness~ copper*community, p=0.03). Error bars represent +/-SE (cheat fitness~ copper, p=0.01). Error bars represent +/-SE Microbial communities- Cambridge
Summary • Heavy metal detoxification by bacterial siderophores is a cooperative behaviour, that selects for rapid evolution of social ‘cheats’ • In toxic copper soil, cheat fitness is increased in the presence of the community, but in monoculture conditions only. • Cheats cannot ‘invade’ populations of cooperators in soil as they can in synthetic media. Microbial communities- Cambridge
Thanks for listening! • Angus Buckling • Dave Hodgson • Adela Luján • Florian Bayer • Elze Hesse • Eleanor Van Veen Microbial communities- Cambridge
How is cheat fitness affected by the presence of the soil microbial community? Cu2+ Cheat Cu2+ Cu2+ Cu2+ Cu2+ Cooperator Cu2+ Cu2+ Cu2+ Cu2+ Cu2+ Cheat (species 2) Microbial communities- Cambridge
How is cheat fitness affected by the presence of the soil microbial community? Monoculture Co-culture Cheat relative fitness (w) Cheat relative fitness (w) (cheat fitness~ copper*community, p=0.03). Error bars represent +/-SE (cheat fitness~ copper, p=0.01). Error bars represent +/-SE
Siderophore production: A model system for studying cooperation transportation Fe3+ Fe2+ Fe2+ Mineral/protein Fe3+ Fe3+ siderophore producer West SA, Buckling A. 2003 Cooperation, virulence and siderophore production in bacterial parasites. Proc.R.Soc.Lond.B 270:37 – 44. Griffin AS, West SA, Buckling A. 2004 Cooperation and competition in pathogenic bacteria. Nature. 430 :1024 – 1027 West SA, Diggle SP, Buckling A, Gardner A, Griffin AS. 2007 The social lives of microbes. Annu. Rev. Ecol. Evol.Syst.38:53 – 77. Microbial communities- Cambridge
Siderophores bind other heavy metals too… Cu2+ ✗ Cu2+ Cu2+ Cu2+ Cu2+ Cu2+ Cu2+ Cu2+ Cu2+ Cu2+ siderophore producer …but don’t take them into the cell Braud A, Geoffroy V, Hoegy F, Mislin GLA, Schalk IJ. 2010 Presence of the siderophores pyoverdine and pyochelin in the extracellular medium reduces toxic metal accumulation in Pseudomonas aeruginosa and increases bacterial metal tolerance. Environ Microbiol. 2: 419 – 425 Microbial communities- Cambridge