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Antibiotics and the art of bacterial war

2015; National Academy of Sciences; Volume: 112; Issue: 35 Linguagem: Inglês

10.1073/pnas.1513608112

1091-6490

Daniel M. Cornforth, Kevin R. Foster,

Bacterial biofilms and quorum sensing

“He will win who knows when to fight and when not to fight.”― Sun Tzu, The Art of War, circa 500 BC (1) Microbes are remarkably social. They live in complex, interdependent communities where they share and exchange a variety of beneficial compounds ranging from cell−cell signals to iron-scavenging siderophores to digestive enzymes. Cooperation, particularly between cells of a single genotype (2), is fundamental for how cells survive and grow. However, life is not always so amicable. Microbes are regularly confronted by other genotypes armed to the teeth with weapons including secreted toxins, domesticated viruses, and even poisoned spears. Some microbial toxins have been exploited for decades to produce clinical antibiotics. However, several papers have argued that many antibiotics at their low, ecologically relevant concentrations are, in fact, friendly signals that coordinate community functions (3). A study in PNAS by Abrudan et al. (4) challenges this view, focusing on 13 natural bacterial strains from the most famous genus of antibiotic producers, Streptomyces . The authors seek to firmly reestablish antibiotic production and regulation in terms of the logic of attack and defense. Streptomyces strains are well known to inhibit and kill one another, but what determines the strength and impact of these attacks? To address this question, Abrudan et al. (4) studied how antibiotic inhibition from one strain changes when a second strain is nearby. All strains were studied under two conditions: “asocial” and “social” (Fig. 1 B ). The asocial experiments evaluated the baseline tendency of one strain to harm others. This was done by simply growing a focal strain alone on agar for a few days before adding a target strain on top (in soft agar) and asking whether this second strain could grow. The social experiments were different in that the focal strain was grown next to … [↵][1]1To whom correspondence may be addressed. Email: dcornforth{at}gmail.com or kevin.foster{at}zoo.ox.ac.uk. [1]: #xref-corresp-1-1