07/01/1990 - 06/30/1992
- Robin F. Harris, UW-Madison
The contamination of soils, sediments, groundwater and surface waters by herbicides poses major cleanup problems. This project focuses on atrazine, but involves development of a bioremediation protocol applicable for herbicides. Atrazine is one of the most commonly detected organic contaminants in groundwater throughout Wisconsin. The report describes initial experiments evaluating a conceptual computer model used to establish experimental methodology and design for selective enrichment of aerobic mixed microbial cultures capable of accelerated destruction of atrazine. Preliminary studies have focused on development of analytical procedures to determine the concentration of atrazine and its metabolites, ammonium, and microbial biomass. Values derived from these experiments have been used to determine initial input parameters for the computer model using Pseudomonas sp. strain D. Recoveries of atrazine by gas chromatography were variable (74 to 123%). Recoveries of cyanuric acid using high pressure liquid chromatography (HPLC) were 100.0 ± 0.3%. HPLC was the method of choice to detect atrazine metaolites. Pseudomanas sp. strain D, under ultimately nitrogen-limiting conditions, had an average specific growth rate of 0.27 ± 1.5 grams of protein produced per mole of nitrogen consumed. Pseudomonas sp. strain D, under ultimately carbon-limiting conditions, had an average specific growth rate of 0.34 ± 0.02 1/hr, 45.5 ± 4.3% protein content, and specific growth yield of 40.6 ± 13.5 grams of protein produced per mole of nitrogen consumed. Values from both growth experiments were explained by the model, thereby verifying the model’s usefulness.