Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2007
Publication Date: 8/14/2007
Citation: Beier, R.C., Hume, M.E., Anderson, R.C., Oliver, C.E., Callaway, T.R., Edrington, T.S., Nisbet, D.J. 2007. HPLC determination of chlorate metabolism in bovine ruminal fluid. Journal of Environmental Science and Health Part B. 42:717-726.
Interpretive Summary: Salmonella and Escherichia coli are two bacteria that are an important cause of human and animal disease world wide. The chemical, chlorate, is lethal to these bacteria when administered to animals. A simple method to determine the concentrations of chlorate in the cow’s stomach liquid contents (ruminal fluid) is needed. A high performance liquid chromatographic analysis method was developed to measure chlorate in ruminal fluid. Chlorate alone or supplemented with sodium lactate or glycerol was bactericidal to E. coli in anaerobic incubations (the atmosphere was 100% CO2).
Technical Abstract: Salmonella and Escherichia coli are two bacteria that are an important cause of human and animal disease world wide. The chemical, chlorate, is converted to chlorite and is lethal to these bacteria; however, a simple method to determine the levels of chlorate in ruminal fluid is needed to follow chlorate metabolism. A procedure using HPLC was developed for the rapid analysis of chlorate (ClO3**-), nitrate (NO3**-), and nitrite (NO2**-) ions in bovine ruminal fluid samples. The standard curves for chlorite, nitrite, nitrate, and chlorate were well defined linear curves with R**2 values of 0.99846, 0.99106, 0.99854, and 0.99138, respectively. Concentrations of chlorite could not be accurately determined in bovine ruminal fluid because chlorite reacts with or binds a component(s) or is reduced to chloride in bovine ruminal fluid resulting in erroneously low chlorite measurements. A standard curve ranging from 25 to 150 ppm ClO3**- ion was used to measure chlorate, fortified into ruminal fluid, which was more rapidly (P < 0.01) reduced under anaerobic than under aerobic incubation conditions. Chlorate alone or chlorate supplemented with sodium lactate or glycerol was bactericidal in anaerobic incubations. In anaerobic culture, the addition of sodium formate to chlorate-fortified ruminal fluid appeared to decrease chlorate concentrations; however, the sodium formate also appeared to moderate the bacterial effect of chlorate against E. coli. Addition of the reductants, glycerol or lactate, to chlorate-fortified ruminal fluid did not increase the killing of E. coli at 24 h, but may be useful when the reducing equivalents are limiting as in waste holding reservoirs or composting systems required for intense animal production.