H2 Soil Microbiology
Soil microorganisms utilize H2 from the atmosphere so strongly as to comprise its largest sink; however, many fundamental questions surrounding this process remain. Which microorganisms possess the ability to utilize atmospheric H2 at such low concentrations (~500 ppbv)? What, if any, competitive advantage is gained via access to the atmospheric H2 reservoir? Which environmental processes most strongly influence the rate of H2 uptake by these microorganisms? We hope to contribute to our understanding of these questions with our explorations into the microbiology of H2 uptake at Harvard Forest.
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Soil systems – the challenges of complexity and scale
Soils are complex systems, in which physical, geochemical and biological processes interact in aggregate structures situated in dynamically shifting air- and water-filled spaces. It is difficult to adequately sample soil properties and to model processes related to those soil measurements. These challenges were discussed in a stimulating three-day conference on Complex Soils Systems in Berkeley a few weeks ago. Attendees came from an incredible diversity of backgrounds with a common interest in tackling issues in soil science. The need to better understand soils was motivated by the importance of soil processes in climate and for figuring out “How to feed the soil and the planet?” in the anthropocene – a question posed…
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Undergraduate Researcher Shersingh’s SURGE Experience
Congratulations to visiting undergraduate researcher Shersingh Joseph Tumber-Davila on completing and thriving in the demanding eight-week Summer Undergraduate Research in Geoscience and Engineering (SURGE) program! Shersingh came to the Welander lab with a strong background in environmental research (news article) from his home institution of the University of New Hampshire. SURGE is a competitive earth science research and graduate school preparation program, which is specifically designed to recruit students of diverse backgrounds from other universities across the country. I was amazed at the number of activities the program had for the students including GRE test preparation, faculty seminars, career and grad school panels, and field trips. This was all while performing graduate-level research including…
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BioDesign course – bridging science and art
Biologist/architect team Tobi Lyn Schmidt and Mike Bogan created a course linking artists, designers, architects, and biologists from the California College of the Arts (CCA) and Stanford University. I served as a postdoc mentor to help inspire and guide the process of cross-hybridizing biology and design (some examples) with three really talented undergraduate CCA students: Leslie Greene, Sakurako Gibo, and David Lee. The students were first charged with creating designs to illustrate scientific concepts in my field of research. I challenged them think about the issue of scale with respect to the biogeochemical cycles I study. The processes I investigate occur over a wide range of spatial and temporal scales,…
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Manuscript linking consumption of atmospheric H2 to the life cycle of soil-dwelling actinobacteria
Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2). In Meredith et al. (2014) in Environmental Microbiology Reports, we probe the advantage of atmospheric H2 consumption to microbes and relationship between environmental conditions, physiology of soil microbes, and H2. First, we were interested in whether environmental isolates and culture collection strains with the genetic potential for atmospheric H2 uptake (a specific NiFe-hydrogenase gene) actually exhibit atmospheric H2 uptake. To expand the library of atmospheric H2-oxidizing bacteria, we quantify H2 uptake rates by novel Streptomyces soil isolates that contain the hhyL and by three previously isolated and sequenced strains of actinobacteria whose hhyL sequences span the known hhyL diversity. Second, we…
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Deepa attends AGU and blogs about her experience
The EAPS department website shares Deepa’s blog about her first the AGU experience. She writes, “Science, nature, life, emergence, and the universe have always inspired my art. And it is the unnecessary beauty of science that makes it deeply mysterious and so inviting to my mind… AGU was an incredible week of reconnecting with friends, advisors, professors, fellow researchers. It was also unexpectedly a way for me to connect a path to a foreseeable future where my two passions can be combined, perhaps even muddled, into an exciting career.”
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Thesis Defense!
I defended my thesis entitled “Field Measurement of the Fate of Atmospheric H2 in a Forest Environment: from Canopy to Soil”. I was honored to receive the 2012 Carl-Gustaf Rossby Prize for my thesis (link to .pdf). It was an incredible feeling to defend. I really enjoyed preparing and giving my thesis defense presentation. It’s not often that one gets to present the culmination of six years of hard work and personal development to colleagues, family, and friends. I am grateful for mentorship from my advisor Ron Prinn, my thesis committee (Steve Wofsy – Harvard, Bill Munger – Harvard, Tanja Bosak – MIT, Colleen Hansel – WHOI, Shuhei Ono – MIT), and…
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ISME conference on “the power of the small”
Last week I attended ISME 14 (International Symposium on Microbial Ecology) in Copenhagen, Denmark. It was a delight to see the city – its juxtaposed giant modern, cool, sterile buildings surrounding the historic old city. More of a delight was unexpectedly running into friends from the MBL Microbial Diversity summer school (2010) and realizing they are now my colleagues. The conference itself was quite good. I appreciated the range of content from very big picture and abstract to focused experimental projects. One message I took away from the community was a sort of -omics backlash, or perhaps whiplash, to the idea that generating more and more -omics data is the…
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Deepa receives Goetze Prize for Undergraduate Research
At the 2012 EAPS Student Awards Ceremony Deepa Rao received the Christopher Goetze Prize for Undergraduate Research for her thesis entitled : “Exploring the Microbe-mediated Soil H2 sink: A lab-based study of the physiology and related H2 consumption of isolates from the Harvard Forest LTER.” The award recognizes ” innovative experimental design, care in data collection, and sensitive application of results to research problems.” It has been a pleasure to supervise Deepa’s thesis research and her results will contribute to our research efforts to understand the mechanisms driving the soil sink for atmospheric H2. Professor Ron Prinn acts as the faculty advisor for both Deepa and I.
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How much energy does H2 supply to soil microbes?
I presented a poster at the at the Ecology of Soil Microorganisms conference in Prague, 2011 on the role of soil microorganisms in dominating the fate of atmospheric molecular hydrogen (H2). Recent work has linked atmospheric H2 uptake to a novel high-affinity [NiFe]-hydrogenase expressed in active Streptomyces sp. cells, and is perhaps not driven by abiotic hydrogenases as was previously thought. Consequently, atmospheric hydrogen may be a 60-85 Tg yr-1 energetic supplement to microbes in Earth’s uppermost soil horizon. To understand the role of this supplement to the soil microbial ecology, this work explores the following questions: What is the importance of atmospheric H2 energy to soil microbial communities relative to…