@article {4597, title = {Metabolic capacity of the Antarctic cyanobacterium Phormidium pseudopriestleyi that sustains oxygenic photosynthesis in the presence of hydrogen sulfide}, journal = {Genes}, volume = {12}, year = {2021}, month = {03/2021}, pages = {426}, abstract = {

Sulfide inhibits oxygenic photosynthesis by blocking electron transfer between H2O and the oxygen-evolving complex in the D1 protein of Photosystem II. The ability of cyanobacteria to counter this effect has implications for understanding the productivity of benthic microbial mats in sulfidic environments throughout Earth history. In Lake Fryxell, Antarctica, the benthic, filamentous cyanobacterium Phormidium pseudopriestleyi creates a 1\–2 mm thick layer of 50 \µmol L\−1 O2 in otherwise sulfidic water, demonstrating that it sustains oxygenic photosynthesis in the presence of sulfide. A metagenome-assembled genome of P. pseudopriestleyi indicates a genetic capacity for oxygenic photosynthesis, including multiple copies of psbA (encoding the D1 protein of Photosystem II), and anoxygenic photosynthesis with a copy of sqr (encoding the sulfide quinone reductase protein that oxidizes sulfide). The genomic content of P. pseudopriestleyi is consistent with sulfide tolerance mechanisms including increasing psbA expression or directly oxidizing sulfide with sulfide quinone reductase. However, the ability of the organism to reduce Photosystem I via sulfide quinone reductase while Photosystem II is sulfide-inhibited, thereby performing anoxygenic photosynthesis in the presence of sulfide, has yet to be demonstrated.\ 

}, keywords = {LTER-MCM}, doi = {10.3390/genes12030426}, url = {https://www.mdpi.com/2073-4425/12/3/426}, author = {Lumian, Jessica E. and Jungblut, Anne D. and Dillon, Megan L. and Hawes, Ian and Peter T. Doran and Mackey, Tyler J. and Dick, Gregory J. and Grettenberger, Christen L. and Sumner, Dawn Y.} } @article {4582, title = {Environmental control on the distribution of metabolic strategies of benthic microbial mats in Lake Fryxell, Antarctica}, journal = {PLoS ONE}, volume = {15}, year = {2020}, month = {04/2020}, pages = {e0231053}, abstract = {

Ecological theories posit that heterogeneity in environmental conditions greatly affects community structure and function. However, the degree to which ecological theory developed using plant- and animal-dominated systems applies to microbiomes is unclear. Investigating the metabolic strategies found in microbiomes are particularly informative for testing the universality of ecological theories because microorganisms have far wider metabolic capacity than plants and animals. We used metagenomic analyses to explore the relationships between the energy and physicochemical gradients in Lake Fryxell and the metabolic capacity of its benthic microbiome. Statistical analysis of the relative abundance of metabolic marker genes and gene family diversity shows that oxygenic photosynthesis, carbon fixation, and flavin-based electron bifurcation differentiate mats growing in different environmental conditions. The pattern of gene family diversity points to the likely importance of temporal environmental heterogeneity in addition to resource gradients. Overall, we found that the environmental heterogeneity of photosynthetically active radiation (PAR) and oxygen concentration ([O2]) in Lake Fryxell provide the framework by which metabolic diversity and composition of the community is structured, in accordance with its phylogenetic structure. The organization of the resulting microbial ecosystems are consistent with the maximum power principle and the species sorting model.

}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.0231053}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231053}, author = {Dillon, Megan L. and Hawes, Ian and Jungblut, Anne D. and Mackey, Tyler J. and Eisen, Jonathan A. and Peter T. Doran and Sumner, Dawn Y.} }