title: Fate of Escherichia coli O157:H7 and Salmonella in soil and lettuce roots as affected by potential home gardening practices.
abstract: BACKGROUND
  The survival and distribution of enteric pathogens in soil and lettuce systems were investigated in response to several practices (soil amendment supplementation and reduced watering) that could be applied by home gardeners.
  
  
  RESULTS
  Leaf lettuce was grown in manure compost/top soil (0:5, 1:5 or 2:5 w/w) mixtures. Escherichia coli O157:H7 or Salmonella was applied at a low or high dose (10(3) or 10(6) colony-forming units (CFU) mL(-1) ) to the soil of seedlings and mid-age plants. Supplementation of top soil with compost did not affect pathogen survival in the soil or on root surfaces, suggesting that nutrients were not a limiting factor. Salmonella populations on root surfaces were 0.7-0.8 log CFU g(-1) lower for mid-age plants compared with seedlings. E. coli O157:H7 populations on root surfaces were 0.8 log CFU g(-1) lower for mid-age plants receiving 40 mL of water compared with plants receiving 75 mL of water on alternate days. Preharvest internalization of E. coli O157:H7 and Salmonella into lettuce roots was not observed at any time.
  
  
  CONCLUSIONS
  Based on the environmental conditions and high pathogen populations in soil used in this study, internalization of Salmonella or E. coli O157:H7 into lettuce roots did not occur under practices that could be encountered by inexperienced home gardeners.
authors.affiliation: Center for Food Safety and Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Griffin, GA, 30223-1797, USA.
authors.forename: Marilyn C
authors.initials: MC
authors.lastname: Erickson
authors.forename: Jean
authors.initials: J
authors.lastname: Liao
authors.forename: Alison S
authors.initials: AS
authors.lastname: Payton
authors.forename: Cathy C
authors.initials: CC
authors.lastname: Webb
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Guodong
authors.initials: G
authors.lastname: Zhang
authors.forename: Ian
authors.initials: I
authors.lastname: Flitcroft
authors.forename: Michael P
authors.initials: MP
authors.lastname: Doyle
authors.forename: Larry R
authors.initials: LR
authors.lastname: Beuchat
mesh_terms: D019453:Escherichia coli O157; D005308:Fertilizers; D005516:Food Microbiology; D051639:Gardening; D006801:Humans; D018545:Lactuca / Q000382:microbiology*; D008372:Manure; D018515:Plant Leaves; D018517:Plant Roots / Q000382:microbiology*; D012475:Salmonella; D012987:Soil; D012988:Soil Microbiology; D014867:Water
chemical_list: D005308:Fertilizers; D008372:Manure; D012987:Soil; D014867:Water
keywords: Escherichia coli O157:H7; Salmonella; compost amendment; internalization; lettuce; soil; water stress