Where are you from, and what is your role in Extreme 2002?
I just recently joined the scientific staff in the Biology Department of the Woods Hole Oceanographic Institution after being a post-doc there for about 1 1/2 years. During the Extreme 2002 cruise, my colleague Craig Taylor and I will be studying the diversity, distribution, and abundance of a novel sulfide-oxidizing bacterium that possesses the capacity to produce sulfur in filamentous form. In addition, we will be implementing a newly developed device, the Autonomous Microbial Sampler (AMS), which will permit discrete samples to be taken at hydrothermal vents that are free from contaminating microbes and exogenous DNA. This device will be used to collect samples for our research as well as for others on the cruise.
What questions are you trying to answer and why?
We are studying an unusual microbe that oxidizes hydrogen sulfide (H2S) in microaerobic environments and excretes its metabolic waste product — sulfur — in the form of long, irregular filaments (~1-5 um x 500-1000 um). It has adapted to life in high flow and sulfidic aquatic environments by the deposition of these filaments into an interlocking mycelial structure, thereby preventing its removal from the zone in which it is active. The organism belongs to the genus Arcobacter within the -subdivision of the proteobacteria, which previously contained only heterotrophic members, and we gave it the name Candidatus Arcobacter sulfidicus (CAS). CAS is autotrophic via a non Calvin-Benson-Bassham cycle and is able to fix nitrogen. Present evidence suggests that filamentous sulfur formation may be a wide-ranging activity, appearing in a variety of sulfidic coastal environments as well as in deep-sea hydrothermal vent ecosystems in both the Pacific and Atlantic oceans. During eruptive events at hydrothermal vents, filamentous sulfur-producing microbes may be witnessed as a dominant player in the shallow subsurface biosphere.
The overall goal of the present project will be to extend ongoing studies of the microbial ecology of filamentous sulfur formation at hydrothermal vents. So far, little is known about the abundance, distribution, diversity, and function of the unusual Arcobacter organism in situ. I will assess the abundance and distribution in environmental samples by employing fluorescent in situ hybridization (FISH) with existing and newly developed fluorescently labeled oligonucleotides of different specificity targeting the 16S rRNA. Genomic DNA and RNA will be extracted from sulfidic hydrothermal environments for diversity analyses using denaturing gradient gel electrophoresis (DGGE), small-subunit rRNA gene cloning and sequencing. We will also be implementing H2S-enriched continuous flow reactors in simulation of warm-water vents to obtain enrichment cultures of this organism for later study.
Why is this research important? What are the benefits?
The overall significance of this research lies in the characterization of the parameters and mechanisms by which this unique process of autotrophic sulfide oxidation occurs, as well as the abundance, distribution, and genotypic diversity of the responsible microbes in a number of different environments. Results will enhance our knowledge of the physiology and ecology of a novel, and heretofore-unconsidered, component of the sulfur cycle. Filamentous sulfur formation may be an important process at hydrothermal vents, extending into the shallow subsurface biosphere and driven by inorganic nutrients alone (i.e., H2S and CO2, N2).
What's your background and what lured you into marine science/education?
I was born in Mainz (close to Frankfurt/Main), Germany, and I developed an interest in nature early on. In high school, biology became my favorite topic and so it was clear to me that I would study biology at a university. During my undergraduate work in biology at the University of Mainz, I became interested in biological oceanography. Because only the north of Germany has access to the ocean, all marine research in Germany tends to be concentrated in this part of the country. This made it necessary for me to move up to the north, and I started my graduate studies at the University of Bremen. I was particularly fascinated by the field of marine microbiology, since basically all processes in the oceans are driven by microscopically small organisms.
Early during my graduate studies, I was awarded a one-year Fulbright Scholarship to study at the School of Oceanography at the University of Washington (Seattle, WA). It was there that I was first exposed to the microbiology of hydrothermal vents, a field that has captured my scientific curiosity since. This stay in the U.S. also exposed me to a different culture and education system than in Germany, and it has been a very good experience in every respect. I completed my graduate studies upon my return to Bremen. For my Ph.D. thesis, I studied a shallow-water hydrothermal vent system offshore the island Milos in the Aegean Sea (Greece). I then applied for a postdoctoral scholarship at the Woods Hole Oceanographic Institution, which brought me back to the U.S. This will be my first cruise on Atlantis/Alvin, and when I make my first dive to a deep-sea hydrothermal vent, it will be a dream come true for me.
