Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract only
Publication Acceptance Date: 2/21/2003
Publication Date: 5/20/2003
Citation: BERRY, E.D., MILLER, D.N. EFFECT OF MOISTURE AND MANURE CONTENT ON THE GROWTH AND SURVIVAL OF ESCHERICHIA COLI O157:H7 IN CATTLE FEEDLOT SOILS. AMERICAN SOCIETY OF MICROBIOLOGY MEETING. 2003. Abstract p. 550. Interpretive Summary:
Technical Abstract: The moisture and manure content of soils at cattle feedlot surfaces vary spatiotemporally and likely are important factors in the persistence of Escherichia coli O157 and other pathogens in cattle and in the production environment. The objective of this study was to evaluate the impacts of different moisture and manure levels on the survival of E. coli O157, generic E. coli, and coliforms in cattle feedlot soils. Soil and bovine manure were mixed to prepare feedlot soils containing 5, 25, and 75% manure. Six different moisture levels (10% to 60%) were maintained by daily addition of water to the feedlot soils, which were held at 20C. A streptomycin-resistant E. coli O157:H7 was added at an initial level of 5 log CFU/g soil (dry matter). Populations of added E. coli O157 and indigenous generic E. coli and coliforms in the feedlot soils were monitored by direct plating over a two-week period. In general, E. coli O157 numbers either persisted or increased at all but the lowest moisture levels examined. At 10% moisture, E. coli O157 were reduced to below detectable levels at all manure levels, and these reductions were more rapid as manure content decreased. At 30% moisture and 25% manure, E. coli O157 increased by 2 log CFU/g in three days, while at 30% moisture and 75% manure, initial populations remained stable over 14 days. At 40 and 50% moisture and 25% manure, populations of E. coli O157 decreased over time, dropping by >2.5 log CFU/g in 14 days, but at 75% manure, E. coli O157 at 40% and 50% moisture increased by 2 and 2.5 log CFU/g, respectively, in the first seven days. Effects of water and manure content on populations of indigenous E. coli and coliforms were similar to those seen with E. coli O157:H7. We conclude that E. coli O157 can persist and even grow in feedlot soils over a wide range of water and manure contents. These results also show that manure content modulates the effect of moisture on E. coli growth, presumably by affecting the water activity of the feedlot soils. Further investigations will be necessary to determine if these variables can be manipulated to reduce the survival and transmission of this pathogen in cattle and the feedlot environment.