Collective behavior is a common feature of living systems, from schools of fish and flocks of birds to swarms of bacteria. Collective behavior likely contributes to the survival of the population. However, precisely how collective behavior is orchestrated remains poorly understood. Bacteria contribute to the function and health of higher organisms such as plants, animals, and humans. The ability of certain bacteria to move collectively facilitates colonization of their hosts. This project will investigate how certain bacteria coordinate their collective movement by releasing specific chemicals that are likely used as signals by the members of the population. This project will also investigate whether these chemicals are important for host colonization. A bacteria-marine sponge model will be used in these studies. Marine sponges are among the most ancient animals and are a dominant component of oceans worldwide. Work on this project will facilitate training new scientists because it will involve undergraduate and graduate students. This project will also encompass a major outreach effort. Specifically, science workshops will be designed and conducted for an after school program which serves students grades 6-8 in a predominantly Hispanic and African-American neighborhood next to the University of Illinois at Chicago campus. The main objective of the workshops will be to engage middle school students in scientific research by illustrating how bacteria are an essential part of life on Earth and how chemicals are used as a form of language that allows bacteria to communicate with each other and with higher organisms.
Many questions remain to be answered regarding bacterial motility and host interaction. One key question is which specialized metabolites mediate these processes and how they do so. A link was identified between bacterial motility and a conserved nonribosomal peptide synthetase (NRPS) gene cluster family which encodes modified peptides that are likely secreted. The NRPS gene cluster family is conserved in alpha- and gamma-Proteobacteria of the Pseudovibrio and Pseudomonas genera, respectively, which are known to establish beneficial and antagonistic interactions with eukaryotic hosts as diverse as marine sponges (Pseudovibrio), plants and insects (Pseudomonas). Inactivation of this gene cluster in Pseudovibrio brasiliensis impairs swarming and swimming motility. It is hypothesized that the nonribosomal peptides function as previously unknown signaling molecules to promote motility, improving survival and enabling host colonization. During work on the project, mutational, transcriptomic, structural, imaging, relative fitness, and host colonization studies will be integrated to unravel the role of the NRPS gene cluster family using the Pseudovibrio-marine sponge interaction as a model. In addition, mutational, structural, and imaging studies will also be performed with representative Pseudomonas spp. This project is expected to shed light on the conserved mechanisms that Proteobacteria employ to coordinate motility and to colonize eukaryotic hosts, ultimately expanding current knowledge of collective behavior of single cell organisms and of prokaryote-eukaryote interactions.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
