Microbial Degradation of Lignin, Plant Aromatics and Polychlorinated Biphenyls (PCBs) in Boreal Forest Soil

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The goal of this work is to identify genes of bacteria, fungi and other microbes in Alaskan boreal forest soils that are active in the biodegradation of a variety of aromatic (ringed) compounds, including lignin, plant secondary compounds and polychlorinated biphenyls (PCBs). Stable isotope methods will be employed, which enable the direct identification of microorganisms and genes involved in biodegradation of labeled compounds under natural conditions. Lignin is the second most abundant biological molecule on earth, and comprises 25% of terrestrial biomass. Microbial biodegradation of this compound and other similar plant compounds is a critical component of global carbon cycling and also has practical application to the cleanup of chemically similar environmental pollutants such as polychlorinated biphenyls (PCBs). Alaskan interior forests are particularly attractive for this study since local tree species have extraordinarily high concentrations of the plant compounds of interest. Thus, there may be an abundance of microbes associated with these plants that can effectively degrade these chemicals as well as environmental pollutants. The microbes and genes identified may be useful for the cleanup of polluted sites, and growing plant species that foster these microbes may accelerate the remediation process. Furthermore, this work will provide new insight into carbon cycling in the boreal forest.