User:Ericapryu/sandbox

=== Environmental conditions and social interactions affecting microbial cheating ===

Like many other organisms, bacteria rely on iron intake for its biological processes. However, iron is sometimes difficult to access in certain environments, like soil. Some bacteria have evolved siderophores, iron-chelating particles that seek and bring back iron for the bacteria. Siderophores are not necessarily specific to its producer - sometimes another individual could take up the particles instead. Pseudomonas fluorescens is a bacterium commonly found in the soil. Under low-iron conditions, P. fluorescens produces siderophores, specifically pyoverdine, to retrieve the iron necessary for survival. However, when iron is readily available, either from freely diffusing in environment or another bacterium's siderophores, P. fluorescens ceases production, allowing the bacterium to devote its energy towards growth. One study showed that when P. fluorescens grew in association with Streptomyces ambofaciens, another bacterium that produces the siderophore coelichen, no pyoverdine was detected. This result suggested that P. fluorescens ceased siderophore production in favor of taking up iron-bound coelichen, an association also known as siderophore piracy.

More studies, however, suggested that P. fluorescens' cheating behavior could be suppressed. In another study, two strains of P. fluorescens were studied in the soil, their natural environment. One strain, known as the producer, produced a higher level of siderophores, which meant that other strain, known as the non-producer, ceased siderophore production in favor of using the other's siderophores. Although one would expect that the non-producer would outcompete the producer, like the P. fluorescens and S. ambofaciens association, the study demonstrated that the non-producer was unable to do so in soil conditions, suggesting that the two strains could coexist. Further experiments suggested that this cheating prevention may be due to interactions with other microbes in the soil influencing the relationship or the spatial structure of the soil preventing siderophore diffusion and therefore limiting the non-producer's ability to exploit the producer's siderophores.