Microcosm experiment data of microcystin-degrading bacteria in Lake Erie source waters and drinking-water plants, 2015-18

In 2015-2018, the U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency Great Lakes Restoration Initiative investigated the biodegradation of microcystins in source waters and sand filters from drinking-water plants in the Western Lake Erie Basin. Four source waters and three sand filtrate samples were collected from the intakes and sand filters of Lake Erie drinking-water plants and transported to the USGS Ohio Water Microbiology Laboratory, where investigators set up microcosms to enrich for and identify indigenous bacteria capable of degrading microcystins. Quality control samples were set up in the microcosms to check analyses and included positive controls, negative controls, and replicates. Microcystin biodegradation was quantified by the disappearance of the toxin as compared to control cultures in microcosm and microplate experiments, and by the presence of a gene within microcystin-degrading bacteria that encodes for an enzyme involved in the initial steps of biodegradation. Bacteria were isolated from microcosms enriched with microcystin-LR (MC-LR) and MC-LR concentrations were measured over time by ELISA (table 1). Isolates were selected from the microcosm experiments for further growth testing in microplate experiments with various enrichment media and MC-LR over 96 hours (table 2). Biofilm formation potential for the isolates were also measured and data is shown in table 3. Isolate absorbances of ten potential microcystin degraders were incubated in a microplate with MC-LR as the sole carbon source (table 4) and concentrations of MC-LR in microplate wells were measured over time (table 5).