Project: EAGER: Harnessing the power of short-read technology to investigate unexplored microbial communities in the deep euphotic zone

Extracted from the NSF award abstract:

Recent advances in genome sequencing have transformed marine microbial ecology. Metagenomic datasets have led to the discovery of new protein families, underscored the importance of the rare biosphere and even allowed the study of intra-population diversity of dominant members of the community such as Prochlorococcus. Although open ocean microbial communities have been repeatedly demonstrated to vary significantly with depth, in terms of both phylogenetic diversity and biogeochemical function, the vast majority of sequence available in public databases is from surface waters. Much less is known about microbial communities below the surface of the ocean, even those at 50-200m. Next generation sequencing technologies offer a dramatic reduction in cost per base compared to Sanger or even pyrosequencing approaches. The very short read lengths from these platforms have not yet been successfully applied to mixed communities. This project is a metagenomic study of the microbial communities throughout the water column in the South Atlantic gyre using the ABI SOLiD platform with the following objectives:

- Construct and sequence paired-end metagenomic libraries from the surface, chlorophyll maximum, deep euphotic zone and twilight zone in the South Atlantic gyre using ABI SOLiD technology.

- Apply information theory based software methods to assemble the short read sequences and reconstruct the phylogenetic diversity and metabolic potential of these communities.

- Compare reconstructed sequences to existing metagenomic data from other parts of the world's oceans and to metaproteomic data from the the same location to inform sampling strategies and methodological choices for a proposed global molecular oceanic survey (Biogeotraces). 

This project is appropriate as an EAGER because the genomic potential of deep euphotic zone and twilight zone communities will be very different from those in surface waters. Thus, this dataset will reshape our understanding of oligotrophic community function. Second, the massive advance in data generated at a low cost by short-read sequencing platforms has the potential to transform microbial oceanography by allowing metagenomic analyses to be routinely employed in hypothesis-driven experiments. However, new interdisciplinary tools are required to assemble and interpret this data. Until these next generation bioinformatic methods are established, proposals that take advantage of these technological breakthroughs remain high risk.

Broader Impacts: Metagenomic analyses of microbial communities collected on a GEOTRACES compliant cruise in the South Atlantic will provide a pilot dataset demonstrating the potential of short-read sequencing technologies for a future sectional molecular survey program. A post-doctoral researcher and a graduate student will be trained in the interdisciplinary perspectives required to analyze this sequence data and interpret it in a biogeochemical context.