This C-DEBI Research Exchange was awarded for travel to the ECORD Summer School Course: Subduction Zone Processes hosted by MARUM in Bremen, Germany. This course offered many unique opportunities including networking with international scientists of various disciplines, learning shipboard operations, and improving grant writing abilities. This two-week course surveyed various types of subduction zone environments and included a wide variety of topics including geology, petrology, geochemistry, sedimentology, and microbiology. We participated in small group exercises that surveyed physical properties, core logging, rock geochemistry, downhole logging, core descriptions, thin sections, and temperature and heat flow. Each of these activities were mimicking onboard operations which allowed us to understand how sediment cores were processed on expeditions. This experience allowed me to make numerous contacts with future colleagues and collaborators while also receiving training for future expeditions. This course was relevant to C-DEBI Research Themes 2 (Activities, Communities, and Ecosystems) and 3 (Metabolism, Survival, and Adaptation) because we connected life with surrounding abiotic conditions including geochemistry, geology, petrology, and sedimentology.
Microorganisms possess a variety of survival mechanisms, including the production of antimicrobials that function to kill and/or inhibit the growth of competing microorganisms. Studies of antimicrobial production have largely been driven by the medical community in response to the rise in antibiotic-resistant microorganisms and have involved isolated pure cultures under artificial laboratory conditions neglecting the important ecological roles of these compounds. The search for new natural products has extended to biofilms, soil, oceans, coral reefs, and shallow coastal sediments; however, the marine deep subsurface biosphere may be an untapped repository for novel antimicrobial discovery. Uniquely, prokaryotic survival in energy-limited extreme environments force microbial populations to either adapt their metabolism to outcompete or produce novel antimicrobials that inhibit competition. For example, subsurface sediments could yield novel antimicrobial genes, while at the same time answering important ecological questions about the microbial community.
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.