A C-DEBI research exchange was awarded for travel to the International Geobiology Summer Course hosted by California Institute of Technology (in conjuction with the Agouron Institute, Simons Foundation and USC Wrigley Institute). This course offered many unique opportunities including extensive field sampling, lab work, and data analyses. Field sampling occurred at Mono Lake, Little Hot Creek, the Monterey Formation, and Sulfur Mountain. Laboratory procedures included DNA extraction and PCR, CARD-FISH, microeukaryote culturing, nanoSIMS, beamline, SEM, biomarker, isotopes, and petrography analyses. We found that there was potential for microbial communities to be active at low levels in Mono Lake sediments. We also concluded that there were detrital input of albite and orthoclase into Mono sediments that correlated with El Niño and La Niña events. These data were analyzed and presented for the participants, directors, and course administrators on the final day. This experience not only provided me with technical training, but also allowed me to build an extensive network of colleagues in the field of geobiology. This course was relevant to C-DEBI Research Themes 2 (Activities, Communities, and Ecosystems) and 3 (Metabolism, Survival, and Adaptation) because we connected microbial community structure and potential function to geochemical measurements.
Microbial life in the deep subsurface biosphere is taxonomically and metabolically diverse, but it is vigorously debated whether the resident organisms are thriving (metabolizing, maintaining cellular integrity, and expressing division genes) or just surviving. As part of Integrated Ocean Drilling Program (IODP) Expedition 347: Baltic Sea Paleoenvironment, we extracted and sequenced RNA from organic carbon-rich, nutrient-replete, and permanently anoxic sediment. In stark contrast to the oligotrophic subsurface biosphere, Baltic Sea Basin samples provided a unique opportunity to understand the balance between metabolism and other cellular processes. Targeted sequencing of 16S rRNA transcripts showed Atribacteria (an uncultured phylum) and Chloroflexi to be among the dominant and the active members of the community. Metatranscriptomic analysis identified methane cycling, sulfur cycling, and halogenated compound utilization as active in situ respiratory metabolisms. Genes for cellular maintenance, cellular division, motility, and antimicrobial production were also transcribed. This indicates that microbial life in deep subsurface Baltic Sea Basin sediments was not only alive, but thriving.