Discipline: Ecology Environmental and Earth Sciences
Subcategory: Pollution/Toxic Substances/Waste
Saidah Whack - Claflin University
Co-Author(s): Randall Harris, Claflin University, Orangeburg, SC
Microbial bioremediation is the use of microorganisms to remove or reduce toxic pollutants from groundwater and soil. Federal and industrial sites have a major problem with pollutants such as heavy metals. The purpose of the experiment conducted was to use bacterial isolates from the Savannah Rivers Site soil sample to reduce hexavalent chromium (Cr6+) to the less toxic trivalent chromium (Cr3+). Bacteria were grown from diluted soil samples on brain heart infusion (BHI) agar. Isolates with different colony morphologies were restreaked onto BHI agar. The bacteria were then streaked onto BHI plates with different concentrations of Cr6+ in the form of potassium dichromate (K2Cr2O7) ranging from 25 ppm to200 ppm. Of the eight isolates tested, SRS1 survived in 200 ppm of K2Cr2O7. The SRS 1 growth curve showed that in 25 ppm and 50 ppm the bacteria grew similarly to the bacteria containing no Cr6+. At 100 ppm and 200 ppm, the exponential growth rate was decreased resulting in less overall growth at 48 hrs. The Cr6+ concentration was determined using the S-diphenylcarbazide (DPC) reagent. SRS1 was incubated with 50 ppm of K2Cr2O7 and clarified supernatants were assay for at Cr6+ 0, 24, and 48 hr. No Cr6+ was detected after 24 hr of incubation. Future studies will focus on further characterizing the chromium reduction of SRS1.
Funder Acknowledgement(s): HBCU-UP
Faculty Advisor: Randall Harris,