Award: OCE-1657818

Bacterial and phytoplankton play a central role in the cycling of energy and nutrients throughout the marine environment. In order to better understand the interactions between the ocean and biogeochemical cycles and the global climate, the interactions between these two microbial groups needs to be better explored. The goal of our research was to investigate the relationship between a species of marine bacteria, known to produce infochemicals, and marine phytoplankton. Our previous work had shown that when these two microbes were grown together, phytoplankton growth was inhibited, driven by the presence of the bacterially derived signaling molecule, 2-heptyl-4-quinolone (HHQ). With this funding we interrogated the transcriptome and proteome of phytoplankton upon exposure to HHQ. We found that HHQ induces cell-cycle arrest in phytoplankton likely by inhibiting DNA replication and repair. We also demonstrated that exposure to HHQ protected the phytoplankton against mortality due to viral infection. Other work done with this funding found that in field populations, HHQ can fundamentally alter microbial growth rates and community composition, thereby directly influencing the function of marine microbial communities. This work also trained at least 20 undergraduate students, several from underrepresented groups located at Haverford College. One of the seminal papers from this funding was led by an undergraduate first author, and 9 (Oscar, Megan, Genevieve, Eleanor, Isabelle, Jason, Scott, Russell, Elly) undergraduate students presented invited oral or poster presentation at national conferences (Ocean Science, Aquatic Sciences Meeting). Additionally, a focused summer experience with six students and NSF-funded postdoctoral investigator was also held, providing the students with exposure to the transdisciplinary PI team and the experience with participating in collaborative science. Last Modified: 04/12/2022 Submitted by: Kristen Whalen