Dynamic social behaviour in a bacterium:Pseudomonas aeruginosapartially compensates for siderophore loss to cheats

Abstract

Cooperation underlies diverse phenomena including the origins of multicellular life, human behaviour in economic markets and the mechanisms by which pathogenic bacteria cause disease. Experiments with microorganisms have advanced our understanding of how, when and why cooperation evolves, but the extent to which microbial cooperation can recapitulate aspects of animal behaviour is debated. For instance, understanding the evolution of behavioural response rules (how should one individual respond to another's decision to cooperate or defect?) is a key part of social evolution theory, but the possible existence of such rules in social microbes has not been explored. In one specific context (biparental care in animals), cooperation is maintained if individuals respond to a partner's defection by increasing their own investment into cooperation, but not so much that this fully compensates for the defector's lack of investment. This is termed 'partial compensation'. Here, I show that partial compensation for the presence of noncooperating 'cheats' is also observed in a microbial social behaviour: the cooperative production of ironscavenging siderophores by the bacterium Pseudomonas aeruginosa. A period of evolution in the presence of cheats maintains this response, whereas evolution in the absence of cheats leads to a loss of compensatory behaviour. These results demonstrate (i) the remarkable flexibility of bacterial social behaviour, (ii) the potential generality of partial compensation as a social response rule and (iii) the need for mathematical models to explore the evolution of response rules in multi-player social interactions.

Social evolution of toxic metal bioremediation in Pseudomonas aeruginosa

“…As the amount of colony pigmentation varied considerably, we classified a colony showing any yellow/green pigmentation after 36 h as a producer; the primary siderophore of P. aeruginosa , pyoverdine, is yellow/green [21]. To complement this assay, the overall level of pyoverdine production in each population was assessed by a pyoverdine-specific excitation–emission assay [22,23]. One per cent of each population was transferred to iron-limited KB medium in a 96-well plate.…”

The evolution of bacterial mutation rates under simultaneous selection by interspecific and social parasitism

“…We selected 19 wild-type and 19 milky colonies at random at the final timepoint, and inoculated each colony into iron-limited KB media. Populations were grown at 278C for 24 h, after which, fluorescence of 180 ml of culture was measured at 460 nm, following excitation at rspb.royalsocietypublishing.org Proc R Soc B 280: 20131913 400 nm using a Biotek Synergy 2 spectrophotometer (standard protocol for measuring pyoverdine production [40,41] …”

Susceptibility Pattern of Pseudomonas Aeruginosa Producing Enzymes Against Antimicrobial Agent Cell Free Supernatant of Lactococcus With the Focus on Its Determining Quantitatively by Od (Enzyme Linked Immune Sorbent Assay)

“…This factor (enzymes production) is one of the virulence factors that added to other factors owned Pseudomonas especially P. aeruginosa [15,16].…”