Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Circuto Escolar 411A, Copilco Universidad, Coyoacán, 04360, Mexico City, Mexico.
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tercer Circuito Exterior, Ciudad Universitaria, Apdo. Postal 70228, C. P. 04510, CDMX, México.
FEMS Microbiol Lett. 2020 May 1;367(10). doi: 10.1093/femsle/fnaa080.
Pseudomonas aeruginosa is one of the main models to study social behaviors in bacteria since it synthesizes several exoproducts, including exoproteases and siderophores and release them to the environment. Exoproteases and siderophores are public goods that can be utilized by the individuals that produce them but also by non-producers, that are considered social cheaters. Molecularly exoprotease cheaters are mutants in regulatory genes such as lasR, and are commonly isolated from chronic infections and selected in the laboratory upon serial cultivation in media with protein as a sole carbon source. Despite that the production of exoproteases is exploitable, cooperators have also ways to restrict the growth and selection of social cheaters, for instance by producing toxic metabolites like pyocyanin. In this work, using bacterial competitions, serial cultivation and growth assays, we demonstrated that rhamnolipids which production is regulated by quorum sensing, selectively affect the growth of lasR mutants and are able to restrict social cheating, hence contributing to the maintenance of cooperation in Pseudomonas aeruginosa populations.
铜绿假单胞菌是研究细菌社会行为的主要模式生物之一，因为它能合成多种外产物，包括外蛋白酶和铁载体，并将它们释放到环境中。外蛋白酶和铁载体是公共物品，可以被它们的生产者以及非生产者利用，后者被认为是社会骗子。分子外蛋白酶骗子是调节基因（如 lasR）的突变体，通常从慢性感染中分离出来，并在实验室中通过在以蛋白质为唯一碳源的培养基中进行连续培养来选择。尽管外蛋白酶的产生是可利用的，但合作者也有方法来限制社会骗子的生长和选择，例如通过产生有毒代谢物如绿脓菌素。在这项工作中，我们使用细菌竞争、连续培养和生长测定，证明了群体感应调控的鼠李糖脂选择性地影响 lasR 突变体的生长，并能够限制社会欺骗，从而有助于维持铜绿假单胞菌群体中的合作。
