Social interactions of marine bacteria (2016)

Undergraduate: Tara Williams

Faculty Advisor: Alecia Septer
Department: Biology

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Bacteria are abundant in the ocean where they can be found at concentrations of approximately one million cells per milliliter. The Vibrionaceae represent a family of heterotrophic bacteria that are broadly distributed in the marine environment, where they play an important role in cycling organic and inorganic compounds and are known to transition between free-living and particle or host-associated life styles. As free-living organisms, bacterial cells may not regularly come into direct contact with other microbes, but the effects of meeting could impact the structure and function of the community. Inter- and intra-specific interactions of naturally co-occurring bacteria in the open-ocean environment is not well understood. To investigate these interactions, water was collected in the North Atlantic Ocean from three depths: the surface, oxygen minimum zone, and bottom. Representative species were cultured using Vibrio-selective medium. The goal of this project was to 1) identify the species-level taxonomy of bacterial isolates, 2) determine their optimal growth conditions, and 3) use co-incubation assays to test for social interactions. 16s rDNA sequences were amplified and sequenced, and results were compared to the nucleotide sequence database and species were identified by their closest match. Co-incubation assays were performed to screen for social interactions among different naturally occurring deep populations. Preliminary results showed evidence for coexistence.