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 a oral and poster presentation at the end of the program. Shersingh approached all these demands with amazing energy and attitude, which we’d really like acknowledge!
In Shersingh’s research, he asked whether microbe-mediated hydrogen (H2) uptake support C mineralization in soils. Soils are a strong sink for atmospheric H2, which is presumably used by soil microorganisms to fuel their energy metabolism. In addition, emissions of H2 have grown since the industrial revolution, so the availability of H2 energy to soil microbes likely also increased. Shersingh tested the influence of excess H2 on the ability of soil microbes to mineralize soil carbon for a variety of carbon substrates, especially those that can be energy intensive (e.g., lignin and lignocellulose). He used Streptomyces ghanaensis as a model organism containing high affinity hydrogenase (H2 uptake) and laccase (lignin breakdown) genes. By measuring carbon dioxide respiration rates and intermediate products involved in the breakdown of lignin and lignocellulose, we found evidence for increased breakdown of lignocellulose (straw) with elevated levels of H2. This may point to a link between the H2 and C biogeochemical cycles in soils that will be interesting to pursue further. This project is in collaboration with Stanford postdoc Marco Keiluweit who specializes in soil carbon cycling.