Philben Research Group

Active projects

Influence of cell wall biochemistry on peat-moss decomposition

Peat bogs are hotspots for natural carbon sequestration and contain about twice as much carbon as there is CO₂ in the atmosphere. The accumulation of organic matter in these ecosystem is due in part to the slow decomposition of Sphagnum (peat moss), the dominant plant in bogs. Research in the Philben lab is investigating the biochemical mechanisms for their slow decomposition. Specifically, we are analyzing the carbohydrate composition of mosses during decomposition to assess the role of unique structural carbohydrates (termed “Sphagnan”) in inhibiting microbial colonization of the moss tissues.

The origins and fate of organic nitrogen

Nitrogen is an essential nutrient for both plants and microorganisms, and it limits growth in many ecosystems. It is relatively abundant in peatlands and tundra soils, but is mostly found in organic compounds that are not readily assimilated into cells. These compounds must be degraded before they are available to support plant or microbial growth. Both the production and decomposition of organic matter are therefore dependent on the turnover of these organic nitrogen compounds, so understanding their dynamics is essential for predict future carbon cycling in these ecosystems.

Research in the Philben lab is characterizing the relationship between the origins of organic nitrogen and its bioavailability. Analysis of biomarker molecules such as hydroxyproline (found only in plant cell wall proteins) and amino sugars (found in bacterial peptidoglycan) can indicate which type of organisms synthesized organic nitrogen. Differences in origin are hypothesized to be important in determining their bioavailability; for example, nitrogen compounds synthesized by bacteria appear to selective associate with mineral surfaces, protecting them from decomposition. This research will help to predict the long-term response of Arctic and boreal ecosystems to climate change, as the gain or loss of CO₂ from soils will be heavily dependent on the future availability of nitrogen.

Join the Philben Group

We are always looking for new lab members! The group is interdisciplinary and there are many roles to fill, so there are opportunities available for students with interests ranging from analytical chemistry to geology to ecology. Email Professor Philben to discuss current opportunities.