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PERSISTENCE OF A SURROGATE FOR A GENETICALLY ENGINEERED CELLULOLYTIC MICROORGANISM AND EFFECTS ON AQUATIC COMMUNITY AND ECOSYSTEM PROPERTIES: MICROCOSM AND STREAM COMPARISONS
Citation:
Bott, T. AND L. Kaplan. PERSISTENCE OF A SURROGATE FOR A GENETICALLY ENGINEERED CELLULOLYTIC MICROORGANISM AND EFFECTS ON AQUATIC COMMUNITY AND ECOSYSTEM PROPERTIES: MICROCOSM AND STREAM COMPARISONS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/009.
Description:
Our research objectives were to: (1) determine the persistence of an introduced surrogate (Cellulomonas sp NRC 2406) for a genetically engineered microorganism (GEM) in three streamlined habitats; sediments, growths of Cladophora (Chlorophyta), and leaf packs, (2) test ommunity and ecosystem tructural nd unctional responses to the introduced bacteria, and (3) evaluate, by direct comparison to the field, the utility of flowing water mesocosms as tools for the fates and effects of introduced bacteria in streams. C. sp. densities were determined from epifluoresence microscopic counts of samples stained with fluorescent antibodies. aximum post-inoculation densities were < 1% of the total bacterial community in two experiments, and = 25% of total densities in leaf packs in a third experiment. ensities declined from post-inoculation maxima faster in sediments than in C. glomerata growths and leaf packs. . sp. persisted in leaf packs at densities significantly greater than background. . sp had no statistically significant effects on primary productivity, community respiration, assimilation ratios, P/R ratios and bacterial productivity. ellulase concentrations were positively correlated with C. sp densities in fresh leaf litter for 2 days following exposure in one experiment. otal bacterial density algal biomass, and total viable biomass sometimes differed between control and experimental systems, but differences were not related to C. sp. introduction. Leaf litter decomposition (measured by losses of organic mass and cellulose and rates) was not accelerated by C. sp. esocosms were ood tools for studying bacterial population dynamics in leaf litter and physiological aspects of the litter degradation, but they were less were less suited for measuring litter mass and cellulose because physical abrasion during storm accelerated those losses in the field.