Research Product

These studies address two concerns relative to genetically engineered microorganisms (GEMs) in the environment. The first is whether a bacterial population with a salient property of a GEM will persist in natural communities, possibly displacing other populations, and affect community and ecosystem properties. By assessing several response variables, the studies are designed to pinpoint those of greatest utility in detecting effects of the organism. Second, experiments will be conducted both in microcosm streams and a natural stream in order to assess the equivalence of microcosm and field data, and thereby assess the utility of stream microcosms for assessing the fate and effects of GEMs in natural systems. We are working with surrogates for a GEM with enhanced cellulose degrading capability. Cellulose 'superdegrader' GEMs are of interest to the food and paper industries and in the conversion of biomass to fuels. While a surrogate will not mimic a GEM in all physiological and ecological respects, the use of the surrogate allows field studies with the organism and microcosm validation as preludes to studies with a GEM whose safety has been adequately insured. In nature, enhanced cellulose degradation could affect rates and pathways of carbon cycling. Our research focuses on stream ecosystems, since they often receive waste discharges and non-point source inputs. Since there is close interaction between streams and their watersheds, GEMs could also be introduced into streams during storm runoff, during applications on cropland, or in groundwater. White Clay Creek, the study stream, drains a protected rural watershed in southeastern (Chester County) Pennsylvania.