How surface sensing and second messenger signal dynamics control time-dependent biofilm outcomes

The National Institute of Allergy and Infectious Diseases awarded the University of California, Los Angeles $575,966 on July 13, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to investigate how surface sensing and second messenger signal dynamics control biofilm formation in Pseudomonas aeruginosa.

The research tests the central hypothesis that surface sensing signals are transduced into multigenerational cAMP and cyclic-di-guanosine monophosphate (cdGMP) signal histories that promote specific time-dependent bacterial surface phenotypes. The work addresses the gap between the established binary paradigm—in which low cdGMP corresponds to planktonic behavior and high cdGMP to biofilm formation—and the observed complexity of time-dependent phenotypic behaviors during biofilm initiation, including motility shutdown and reactivation, exopolysaccharide-guided trail following, and transitions to molecular adhesion. The research program consists of four aims: testing diguanylate cyclase and phosphodiesterase enzymes that create the temporal structure of multigenerational cdGMP signal histories; testing how combined cAMP and cdGMP signal histories influence type IV pilus-mediated surface sensing and motility; and examining how signal complexity governs biofilm phenotypes and commitment or detachment decisions, using imaging, artificial intelligence-based analysis, reporter systems, and genetic approaches.

Performance occurs at Los Angeles, California, with an ultimate completion date of June 30, 2031. The Trustees of Dartmouth College, operating through its Office of Sponsored Projects, receives a sub-award (R01AI203081-05180000607818) dated September 2, 2026, to contribute expertise in biofilm research on Pseudomonas aeruginosa.

Abstract

Biofilms are surface-attached microbial communities that pose a significant clinical challenge. Biofilm infections incur costs of >1 billion dollars annually. Lethal pseudomonas aeruginosa biofilm infections are common in cystic fibrosis (CF) and other respiratory diseases. Prior to forming a biofilm, a bacterium must sense and a surface via 2ND messenger signaling. In the current "binary" paradigm, low cyclic-diguanylate (CDGMP) levels correspond to planktonic behavior, while high CDGMP levels correspond to biofilm behavior.however, IT is not clear how 2ND messenger signals encode the complex range of time-dependent phenotypic behaviors in biofilm formation, such as pre-biofilm motility shutdown and reactivation, exopolysaccharide (EPS)-guided "trail following", or EPS transition to "molecular glue." we have recently shown that both camp and cdigmp levels undergo strong multigenerational oscillations during P. Aeruginosa biofilm initiation. For single cells at short times, IT is the increase of intracellular cdigmp that corresponds to biofilm development. For an entire lineage of cells, in contrast, the initial cdigmp increase is in fact the initial stage of a complex signaling trajectory with oscillatory components that controls diverse phenotypes. We propose to test the following central hypothesis: surface sensing signals are transduced into multigenerational camp and CDGMP histories that promote specific time- dependent bacterial surface phenotypes. This program of work will consist of the following 4 aims. 1) test the hypothesis that specific diguanylate cyclase (DGC) and phosphodiesterase (PDE) create the time structure of multigenerational CDGMP signal histories. 2) test the hypothesis that combined camp and CDGMP signal histories influence TFP-mediated surface sensing and motility. 3) test the hypothesis that combined camp and CDGMP signal histories control the evolution of EPS elasticity by influencing EPS production, post-secretion crosslinking, and enable bacterial "trail following" behavior. (4) test the hypothesis that camp/CDGMP signal histories are required for flagellum-driven surface detachment. We aim to achieve the most comprehensive mechanistic understanding the events in early biofilm formation currently available.