PATTERNS OF ANOXYGENIC PHOTOTROPHY IN THE LAURENTIAN GREAT LAKES

Bacteria that use bacteriochlorophyll for anoxygenic phototrophy, known as AAPB, can support a range of unique metabolic strategies in aquatic environments and remain an understudied and ecologically important group. 341 dereplicated metagenome assembled genomes (MAGs) from the Laurentian Great Lakes were analyzed for the presence of 27 anoxygenic photosystem genes with Kegg orthologs. This search revealed that 64 of the 341 MAGs found across three different taxonomic classes indicated having the capability for anoxygenic phototrophy. A majority of these AAPB were found in the order Burkholderiales in the Gammaproteobacteria, with the rest residing in the Alphaproteobacteria and Gemmatimonadetes classes. Across the five lakes, these bacteria were primarily found in samples from lakes Erie, Michigan, and Huron with a majority of the group found in epilimnion samples. Additionally, there was a wide diversity of distribution patterns for the AAPB MAGs across different samples including some species that were found in nearly all the samples, species found in only samples from Lake Erie, and others found in only the surface samples. Furthermore, within individual taxonomic clades, closely related taxa of AAPB showed a lake-driven partitioning of their abundances. The AAPB MAGs showed distinct genome characteristics, including a large genome size, high GC-content, as well as low carbon in their proteomes. The overall abundance of AAPB in a sample was positively correlated with temperature, phosphorus and chlorophyll, and negatively correlated with depth and oxidized nitrogen, highlighting their role as surface-dwelling organoheterotrophs.

Primary Presenter: Corey Rundquist, University of Chicago (crundquist@uchicago.edu)

Authors:

Maureen Coleman, University of Chicago  (mlcoleman@uchicago.edu)

Jessi Hart, University of Chicago  (hartjl@uchicago.edu)

Justin Podowski, Argonne National Laboratory  (jpodowski@uchicago.edu)