TRANSCRIPTIONAL MARKERS OF ORGANIC SUBSTRATE AVAILABILITY IN A COASTAL MARINE BACTERIUM

The marine carbon pool is a complex source of nutrients for microbes, which is found within the context of highly complex microbial community, making it difficult to identify which carbon substrates are supporting which microbes in the ocean. One approach to identifying which substrates are driving the marine carbon cycle is to use bacterial cells as a biosensor of the labile substrates available to the community using transcriptomics. To determine if transcriptomics could be used as a reliable indicator of substrate availability, a batch culture approach was taken with the heterotrophic bacterium Rugeria Pomeroyi (DSS-3)- a common and abundant bacteria in coastal oceans. DSS-3 was grown in a glucose and carbon substrate mix including succinate, DMSP, TMAO, leucine, glycerol, and benzoate. RNA was sequenced at the exponential phase of growth and differential gene expression for each treatment was quantified. We are able to see strong correlations between carbon substrate availability and gene expression, specifically in transporter genes and genes at the beginning of these various metabolic pathways. Overall, we were able to identify several genes in metabolic pathways enriched for DSS-3 that can be applied to environmental metatranscriptomic datasets, offering an avenue to identify carbon substrates present without a need for complex chemical analyses. This work is providing insights into the relationship between carbon substrate availability and an organisms physiological and metabolic responses, generating insights into microbial roles in ocean carbon cycling.

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Primary Presenter: Samantha Cerda, University of North Carolina at Chapel Hill (samanth@email.unc.edu)

Authors:

Samantha Cerda, University of North Carolina at Chapel Hill  (samanth@email.unc.edu)

Melanie Cohn, University of North Carolina at Chapel Hill  (mcohn@email.unc.edu)

Scott Gifford, University of North Carolina at Chapel Hill  (sgifford@email.unc.edu)