Progress 09/15/00 to 03/31/04
Outputs
Three different types of compost and irrigation water were inoculated with an avirulent strain of Salmonella Typhimurium at 10 to 7 cfu g and 10 to 5 cfu ml, respectively, to determine the persistence of salmonellae in soils containing these composts and irrigation water, and also on carrots, radishes, leaf lettuce and parsley grown in these contaminated soils. Salmonellae persisted for an extended period of time, with the bacteria surviving in soil samples for 203 to 231 days, and were detected after seeds were sown for 84 and 203 days on radishes and carrots, respectively. Salmonellae persisted for 161 and up to 231 days in soils amended with contaminated composts on which lettuce and parsley, respectively, were grown, and were detected for up to 63 days and 231 days on lettuce and parsley, respectively. Survival profiles of Salmonella on vegetables and soil samples contaminated by irrigation water were similar to those observed when contamination occurred through
compost. Hence, both contaminated manure compost and irrigation water can play an important role in contaminating soil and root vegetables with salmonellae for several months. Studies were done to determine the fate of E. coli O157:H7 in manure compost-amended soil and on carrots and green onions grown in an environmentally controlled growth chamber. Commercial dairy cattle manure compost was inoculated with a 5-strain mixture of gfp-labeled E. coli O157:H7 at 10 to 7 cfu/g and mixed with unsterilized Tifton sandy loam soil at a ratio of 1:5. E. coli O157decreased within 64 days by 3 log cfu/g in soil and soil beneath roots of green onions and by >2 log cfu/g on onions. E. coli O157:H7 survived better during the production of carrots, with a 2.3 log cfu/g reduction in soil and a 1.7 log cfu/g reduction on carrots within 84 days. Results indicate that the type of plant grown is an important factor influencing the survival of E. coli O157 both on the vegetable and in soil in which the
vegetable is grown. We evaluated the potential of two compost tea (CT) systems (aerated tea and non-aerated tea) to support the growth and survival of foodborne pathogens. Compost feedstock, spiked with marked strains of E. coli O157, Salmonella Enteritidis and Enterococcus spp., was used to prepare CT with different temperature and nutrient conditions. We determined the concentration of these pathogens throughout the production of both aerated CT (24 hr) and non-aerated CT (8.5 days). Where nutrients were used to brew the tea, the resulting pathogen concentrations exceeded inoculated levels substantially. The inoculated pathogens and indicators remained undetectable in all CT to which nutrients were not added. Results show that readily metabolized carbon-based nutrient sources support the growth of human pathogens even when dissolved oxygen was less than 6 ppm.
Impacts
Salmonella can survive for several months on carrots, radishes, leaf lettuce and parsley, and E. coli O157:H7 can survive for several months on onions and carrots and in soil under growing conditions, indicating potential contamination of these types of produce when the pathogen is initially present in compost-amended soil or irrigation water. The use of supplemental nutrients to produce compost tea will require additional testing of the final produce to ensure the absence of human pathogens. This is consistent with one of the ten Compost Task Force recommendations accepted by the National Organic Standards Board on October 13, 2004.
Publications
- Erickson, M. C., M. Islam, C. Sheppard, J. Liao, and M. P. Doyle. 2004. Reduction of Escherichia coli O157:H7 and Salmonella enterica serovar Enteritidis in chicken manure by larvae of the black soldier fly. J. Food Prot. 67:685-690.
- Islam, M., J. Morgan, M. P. Doyle, S. C. Phatak, P. Millner, and X. Jiang. 2004. Persistence of Salmonella enterica serovar Typhimurium on lettuce and parsley and in soils on which they were grown in fields treated with contaminated manure composts or irrigation water. Foodborne Pathogens and Disease 1(1):27-35.
- Islam, M., J. Morgan, M. P. Doyle, and X. Jiang. 2004. Fate of Escherichia coli O157:H7 in manure compost-amended soil and on carrots and onions grown in an environmentally controlled growth chamber. J. Food Prot. 67:574-578.
- Jiang, X., M. Islam, J. Morgan, and M. P. Doyle. 2004. Fate of Listeria monocytogenes in bovine manure-amended soil. J. Food Prot. 67:1676-1681.
- Islam, M., J. Morgan, M. P. Doyle, S. C. Phatak, P. Millner, and X. Jiang. 2004. Fate of Salmonella enterica serovar Typhimurium on carrots and radishes grown in fields treated with contaminated manure composts or irrigation water. Appl. Environ. Microbiol. 70:2497-2502.
- Islam, M., M. P. Doyle, S. C. Phatak, P. Millner, and X. Jiang. 2004. Persistence of enterohemorrhagic Escherichia coli O157:H7 in soil and on leaf lettuce and parsley grown in fields treated with contaminated manure composts or irrigation water. J. Food Prot. 67:1365-1370.
- Islam, M., M. P. Doyle, S. C. Phatak, P. Millner and X. Jiang. 2005. Survival of Escherichia coli O157:H7 in soil and on carrots and onions grown in fields treated with contaminated manure composts or irrigation water. Food Microbiology 22:63-70.
|
Progress 01/01/03 to 12/31/03
Outputs
Studies were done to determine the fate of Escherichia coli O157:H7 in manure compost-amended soil and on carrots and green onions grown in an environmentally controlled growth chamber. Commercial dairy cattle manure compost was inoculated with a five-strain mixture of green fluorescent protein-labeled E. coli O157:H7 at 10to7 colony-forming units (CFU)/g and mixed with unsterilized Tifton sandy loam soil at a ratio of 1:5. Baby carrot or green onion seedlings were planted into the manure compost-amended soil in pots, and soil samples surrounding the plant, edible carrot roots and onion bulbs samples, and soil samples immediately beneath the roots were assayed for E. coli O157:H7 in triplicate at weekly intervals for the first four weeks, and every 2 weeks for the remainder of the plant growth cycle (up to 3 months). E. coli O157:H7 cell numbers decreased within 64 days by 3 log cfu/g in soil and soil beneath roots of green onions and by >2 log cfu/g on onions. E.
coli O157:H7 survived better during the production of carrots, with a 2.3 log cfu/g reduction in soil and a 1.7 log cfu/g reduction on carrots within 84 days. Results indicate that the type of plant grown is an important factor influencing the survival of E. coli O157:H7 both on the vegetable and in soil in which the vegetable is grown.
Impacts
E. coli O157:H7 can survive for several months on onions and carrots and in soil under growing conditions, indicating potential contamination of the types of produce when the pathogen is initially present in compost-amended soil.
Publications
- Jiang, X., J. Morgan, and M. P. Doyle. 2003. Fate of Escherichia coli O157:H7 during composting of bovine manure in a laboratory-scale bioreactor. J. Food Prot. 66:25-30.
- Jiang, X., J. Morgan, and M. P. Doyle. 2003. Thermal inactivation of Escherichia coli O157:H7 in cow manure compost. J. Food Prot. 66:1771-1777.
|
Progress 01/01/02 to 12/31/02
Outputs
Three different types of composts, PM-5 (poultry manure compost), 338 (dairy manure compost) and NVIRO-4 (alkaline stabilized dairy manure compost), and irrigation water were inoculated with an avirulent strain of Salmonella enterica serovar Typhimurium at 10 to 7 cfu/g and 10 to 5 cfu/ml, respectively, to determine the persistence of salmonellae in soils contaminated by these composts or irrigation water, and also on various vegetable plants grown in these amended soils. Compost was applied to soil as a strip at a rate of 2 ton/acre (41.6 grams per square food) before seedlings were transplanted. A split-plot block design plan was used for each crop, with five treatments (one without compost, three with each of the three composts, and one without compost but applied with contaminated water) and five replicates for a total of 25 plots for each crop. Each plot measured 6 X 15 feet (90 sq. ft.). Salmonella was detected for an extended period of time, with the bacteria
surviving in all soil samples for 161 days, and detected on lettuce for 63 days, for 84 days on radishes, 166 days on parsley and 203 days on carrots. Survival profiles of Salmonella on plant and soil samples contaminated by irrigation water were similar to those observed when contamination occurred through compost. Hence, both contaminated manure compost and irrigation water can play an important role in contaminating soil and plants with Salmonella.
Impacts
Pathogen survival in soil and on vegetable plants can occur for several months when pathogens are introduced through compost or irrigation water. The studies indicate the need for practical treatments/methods to reduce pathogen contamination of produce during production.
Publications
- Jiang, X., J. Morgan, and M. P. Doyle. 2002. Fate of Escherichia coli O157:H7 in manure-amended soil. Appl. Environ. Microbiol. 68-2605-2609.
- Potter, M., D. Archer, A. Benson, F. Busta, J. S. Dickson, M. Doyle, J. Farber, B. B. Finlay, M. Goldblatt, C. Hedberg, D. Hoover, M. Jahncke, L.-A. Jaykus, C. Kaspar, A. P. Liang, J. Lindsay, J. Pestka, M. Pierson, P. Slade, R. B. Tompkin, and M. L. Tortorella. 2002. Emerging Microbiological Food Safety Issues: Implications for control in the 21st century. Institute of Food Technologists, IFT Expert Report, Chicago, IL. pp. 1-107.
|
Progress 01/01/01 to 12/31/01
Outputs
The fate of Listeria monocytogenes was determined in manure-amended autoclaved and non-autoclaved soil at different manure to soil ratios and held at 5, 15, and 21C. The pathogen survived at 5C for up to 75 days in manure-amended autoclaved soil and for up to 64 days in manure-amended unautoclaved soil. At 15C, the pathogen survived better (71 days) in both soil types when manure was added to soil at a ratio of 1:10, than when the ratio was 1:100 (64 days). At 21C, L. monocytogenes populations in the manure-amended soils declined to undetectable cell numbers by day 43. Survival was substantially greater at all temperatures in the unautoclaved soil amended with manure at a ratio of 1 part manure to 10 parts soil than in the more dilute manure in soil samples of 1:100. However, pathogen populations declined more rapidly in unautoclaved manure-amended soil than in autoclaved soil amended with manure, due likely to antagonistic interactions with indigenous soil
microorganisms. Indigenous microorganisms of soil appear to be the major contributory factors to the inactivation of L. monocytogenes in manure-amended soil. The population of GFP-expressing E. coli O157:H7 in soil and soil under the roots of onion samples steadily decreased by 3 log cfu/g, whereas the pathogen on plant samples decreased by log cfu/g during the same period of time. The E. coli O157:H7 populations of carrots decreased by 2.3 log cfu/g at 84 days in soil samples and by 1.7 log cfu/g at 70 days on carrot plant samples.
Impacts
Pathogen survival in soil and on vegetable plants indicates extended persistence. These studies indicate the need for practical treatments/methods to reduce pathogen contamination of produce during production.
Publications
- No publications reported this period
|
|