BIOREMEDIATIVE POTENTIAL OF CHROMULINA FREIBURGENSIS IN CULTURE FROM THE BERKELEY PIT

Dakel, S. M. 1 & Mitman, G. G. 21 Department of Environmental Engineering; 2 Department of Biological Sciences, Montana Tech of The University of Montana, Butte, MT 59701 USA The Berkeley Pit, part of the largest Superfund site in the United States, is an open‐pit copper mine that operated from 1955 through 1982. Today, the Berkeley Pit contains approximately 1200 billion liters of metal laden water with an average pH of 2.7, and 12 grams/liter of dissolved solids. The principle dissolved ions include aluminum, arsenic, calcium, cadmium, copper, iron, potassium, magnesium, manganese, sulfates, and zinc. A species from Division Chrysophyta–Chromulina freiburgensis Dofl. was isolated from this extreme environment. This species has been tested in the laboratory through a series of controlled experiments to determine bioremediative potential. Optimal temperature was determined by monitoring growth with cell counts at temperatures ranging from 5°C to 40°C . The optimal nutrient ratio was determined by varying nitrogen (NaNO 3 ) and phosphorus (Na 2 HPO 4 ) levels. An experimental matrix varying nutrients was developed to test for bioremediative potential which included: initial and final pH measurements; initial and final Ion Chromatography Pairing–Atomic Emission Spectrometry (ICP‐AES) for dissolved metals; and examination of final samples under Transmission Electron Microscopy (TEM). From these experiments, Chromulina freiburgensis was found to grow optimally in Berkeley Pit surface water with cell densities reaching ten million cells per milliliter at 10°C with additions of 50 mg NaNO 3 /L and 5 mg Na 2 HPO 4 /L. This large biomass was also found to increase diversity and abundance of heterotrophs. At the optimal nutrient level, this species was found to increase pH from 2.21 to 2.47 over 90 days. Significant removal of calcium, iron, nickel, and silica was observed.