Sheryl Bolton culturing microbes in the lab aboard the R/V Melville . Click image for larger view and image credit.
A handful of the more than 400 tubes of growth media cultured to try to mimic the diverse hydrothermal vent environments. The anaerobic media is incubated at high temperatures, ranging from 50°C to 90°C (120 to 195°F). Click image for larger view and image credit.
Despite Challenges Microbes Seem to Prosper
May 5, 2006
Julie Huber
NASA Astrobiology Institute Postdoctoral Fellow
Marine Biological Laboratory, Woods Hole, MA
As the fury of the last week of the cruise begins, it is a good time to catch up on what we have collected and discovered, as well as look ahead and plan what next. The combination of collecting rocks, mats, and fluids have kept us microbiologists busy. These environments present multiple stresses for bacteria and archaea living in the hydrothermal vents. At some sites extreme stresses combine, and we see vents with low pH (<2) and high temperatures (>200°C, ~500°F), not to mention an on-going explosive eruption! Despite these challenges, microbes seem to prosper, and it is our job to figure out how they do it, which is living where, and how they interact with this dynamic geochemical environment.
Sheryl Bolton, a research technician at the University of Washington, is trying to culture some of the strange microbes she first detected here with molecular methods in 2004. Sheryl has put together a plethora (more than 400! tubes) of growth media to try to mimic the diverse vent environments we have found. All of her media is anaerobic, meaning there is no oxygen present, and she is incubating the tubes at high temperatures, from 50°C to 90°C (120 to 195°F). Her efforts were recently rewarded with the collection of multiple active chimneys from East Diamante. The upper-most temperature limit for life is 121°C (250°F), and the fluids passing through the interior of these chimneys are in excess of 200°C, so it is no surprise that Sheryl was only able to culture microbes from the exterior portions of the chimneys. However, the fact that she was able to enrich anaerobic hyperthermophiles at a pH of 4 from samples is exciting, and once back at home, we can figure out exactly who these amazing microbes are and how they survive in the chimneys at East Diamante.
Chimneys are only one target for us, and we have also collected an interesting thermal and chemical suite of vent fluids for culturing, counts, as well as DNA-based molecular methods. We are collecting fluids using the Hydrothermal Fluid Sampler mounted on Jason. This sampler allows David Butterfield to collect fluids for chemistry, and at the same time, we can collect both filtered and unfiltered fluids for microbiological analyses. Once on land, I will extract the community DNA and attempt to get a genetic fingerprint of the entire community. This allows us to determine who is present and in what abundance, without the constraints of culturing. Linking these two methods- culturing and DNA-based methods- along with geochemistry is key to revealing the microbial ecology of hydrothermal vent environments.
Microbes from the exterior portion of this venting chimney were cultured for further analysis. These chimneys are at the top of the 5 Towers chimney complex at East Diamante volcano. Click image for larger view and image credit.
The Hydrothermal Fluid Sampler collecting diffuse fluids at Seamount X. Click image for larger view and image credit.
A cross section of the chimney cultured for microbial studies. The exterior rinds of silica tell us temperatures were likely <70°C (~160°F), where microbes could survive. At the interior temperatures up to 240°C (~460°F) were recorded from the venting fluid - which would preclude any microbes surviving in the interior conduit. Click image for larger view and image credit.
Julie Huber and Dave Butterfield extract fluid samples from the Hydrothermal Fluid Sampler (HFS) after a Jason dive. Click image for larger view and image credit.
