Raghupathi Prem K, Liu Wenzheng, Sabbe Koen, Houf Kurt, Burmølle Mette, Sørensen Søren J
Laboratory of Microbiology, Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Section for Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Front Microbiol. 2018 Jan 9;8:2649. doi: 10.3389/fmicb.2017.02649. eCollection 2017.
Biofilm formation has been shown to confer protection against grazing, but little information is available on the effect of grazing on biofilm formation and protection in multispecies consortia. With most biofilms in nature being composed of multiple bacterial species, the interactions and dynamics of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely and , were constructed and subjected to grazing by the ciliate . In monocultures, grazing strongly reduced planktonic cell numbers in and and also . At the same time, cell numbers in the underlying biofilms increased in and , but not in . This may be due to the fact that while grazing enhanced biofilm formation in the former two species, no biofilm was formed by in monoculture, either with or without grazing. In four-species biofilms, biofilm formation was higher than in the best monoculture, a strong biodiversity effect that was even more pronounced in the presence of grazing. While cell numbers of , and in the planktonic fraction were greatly reduced in the presence of grazers, cell numbers of all three species strongly increased in the biofilm. Our results show that synergistic interactions between the four-species were important to induce biofilm formation, and suggest that bacterial members that produce more biofilm when exposed to the grazer not only protect themselves but also supported other members which are sensitive to grazing, thereby providing a "shared grazing protection" within the four-species biofilm model. Hence, complex interactions shape the dynamics of the biofilm and enhance overall community fitness under stressful conditions such as grazing. These emerging inter- and intra-species interactions could play a vital role in biofilm dynamics in natural environments like soil or aquatic systems.
生物膜的形成已被证明能提供抵御捕食的保护作用，但关于捕食对多物种聚生体中生物膜形成和保护的影响，目前所知甚少。由于自然界中的大多数生物膜是由多种细菌组成的，因此研究了受浮游原生动物捕食者捕食的多物种细菌生物膜的相互作用和动态变化。为此，构建了四种土壤细菌分离株（即 和 ）的单物种和多物种生物膜，并使其受到纤毛虫的捕食。在单培养中，捕食显著降低了 和 以及 中的浮游细胞数量。与此同时，下层生物膜中的细胞数量在 和 中增加，但在 中没有增加。这可能是因为虽然捕食增强了前两个物种的生物膜形成，但 在单培养中，无论有无捕食，都没有形成生物膜。在四物种生物膜中，生物膜的形成高于最佳单培养，这是一种强烈的生物多样性效应，在有捕食的情况下更为明显。虽然在有捕食者的情况下，浮游部分中 、 和 的细胞数量大幅减少，但这三个物种在生物膜中的细胞数量都大幅增加。我们的结果表明，四物种之间的协同相互作用对诱导生物膜形成很重要，并表明当暴露于捕食者时产生更多生物膜的细菌成员不仅保护了自己，还支持了其他对捕食敏感的成员，从而在四物种生物膜模型中提供了“共享的捕食保护”。因此，复杂的相互作用塑造了生物膜的动态变化，并在诸如捕食等压力条件下提高了整个群落的适应性。这些新出现的种间和种内相互作用可能在土壤或水生系统等自然环境中的生物膜动态变化中发挥至关重要的作用。
