With this award, the Chemistry of Life Processes Program in the Chemistry Division of NSF is funding Prof. Allon Hochbaum and Prof. Douglas Tobias at the University of California, Irvine to study the role of detergent-like moecules called biosurfactants in bacterial communication. Bacteria communicate using chemical signals to coordinate behavior throughout dense communities, called biofilms. These coordinated behaviors result in the colonization of surfaces by biofilms, which is problematic in various industrial settings, but biofilms of beneficial microbes also demonstrate great potential in areas of energy, environmental remediation, and waste and chemical processing applications. To control the cultivation or eradication of biofilms in these different scenarios requires an understanding of the compounds and mechanisms responsible for their formation and disassembly. Recent work has established a new role for biosurfactants in mediating bacterial communication. Funding for this project supports microbiological, analytical chemistry, and chemical modeling approaches to advance our understanding of the mechanisms by which bacterial biosurfactants affect chemical communication pathways in biofilms. Research funded by this program supports graduate and undergraduate student training in diverse and interdisciplinary methods related to studies in chemical biology of microorganisms. In the course of this project, these students also develop tools, such as modeling scripts, experimental methods, and bacterial strains, that will be used as part of the labs' educational outreach programs for primary and secondary school programs at UC Irvine.
Research supported by this award will use techniques from microbiology, analytical chemistry, and molecular dynamics (MD) modeling to advance our understanding of the mechanisms by which bacterial biosurfactants affect chemical signaling pathways via cell membrane modulation. A biofilm dispersal assay is used to determine the critical chemical substituents responsible for the biophysical mechanism of activity of a class of glycolipid surfactants, called rhamnolipids. Mutant strains with truncated surfactant biosynthesis and the purification of specific rhamnolipid congeners are used to generate a suite of chemically varied rhamnolipid structures. Mass spectrometry characterizes the effects of specific rhamnolipid exposure, in combination with an acyl-homoserine lactone signaling compound, on intracellular levels of secondary metabolites regulating biofilm and free-swimming phenotypes. Specific mechanistic insight is provided by coupled mass spectrometry, NMR, and MD simulations of bacterial membranes to determine the localization, chemical and biophysical effects of different rhamnolipids on the membrane permeability of specific signaling compounds. These techniques are further applied to known biosurfactants and other amphiphilic signaling compounds produced by a variety of bacteria to advance our understanding of the roles of specific and non-specific chemical and biophysical interactions in determining bacterial community behavior.
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.
