Fate and Transport of Escherichia coli in Tomato Production

Escherichia coli can result in foodborne illnesses and outbreaks to consumers through consumption of contaminated fresh fruits and vegetables. A greenhouse study was conducted to understand the fate and transport of bacteria in soil and tomato fruits. E. coli contaminated irrigation water was applied to tomato plants grown in the greenhouse. Two soil types, namely organic and mineral soil and two irrigation methods, namely drip and sprinkler irrigations were used to generate four different treatments. Tomato fruits in two treatments [drip irrigation and organic soil (D + O), and sprinkler irrigation and mineral soil (S + M)] showed bacterial contamination. However, the D + O treatment might have internalization of bacteria in the tomato fruit. Bacterial contamination in the soil (at the depth of 5-10 cm) was decreasing with time for all the treatments. Organic soil showed more bacteria retention than mineral soil because organic soil is rich in organic matter and organic matter can carry bacteria with it. Sprinkler irrigation posed a higher risk of contamination in the fruits on the 2nd day after inoculation than drip irrigation because the edible part of the crop is in direct contact with the contaminated water. A bacterial count balance study showed that the bacteria were retained mostly in the soil at lower depths of 10-25 cm, in addition to bacterial death in various habitats. The treatment with drip irrigation and mineral soil (D + M) was noticed as the best treatment because it did not show any sign of bacterial contamination in the tomato fruits.