Fate of Escherichia coli in Soil, Leachate and Lettuce and Its Corresponding Health Risk Assessment
摘要
Pathogenic bacteria, such as Escherichia coli, Salmonella, and Shigella, are frequently detected in vegetables and groundwater using polymerase chain reaction (PCR) and culture-based methods. The presence of these pathogens constitutes an increasing threat to global public health. However, knowledge of the fate of pathogenic bacteria in soil–water–plant systems and the factors influencing it remains limited. We investigated the abundance of Escherichia coli in rhizosphere soil, non-rhizosphere soil, leachate, and lettuce leaves using a pot experiment with Calcic Cambisols, and quantitatively assessed the associated health risks. The results revealed that the average concentrations of E. coli in rhizosphere soil, non-rhizosphere soil, lettuce leaves, and leachate were 2.41, 3.18, 3.45, and 4.98log10 CFU/mL, respectively. Permutational multivariate analysis of variance (PERMANOVA) revealed that the survival of E. coli in the soil was significantly (P < 0.01) influenced by biochar and indigenous microorganisms, whereas its survival in both leachate and lettuce leaves was significantly (P < 0.01) influenced by ionic strength, biochar, and indigenous microorganisms. In diverse environmental matrices (soil, lettuce, and leachate), the proportion of E. coli detected fluctuated dynamically. Based on quantitative microbial risk assessment (QMRA), the health risk associated with waterborne disease was greater than that of foodborne disease, with respective probabilities of 2.19 × 10–3 and 2.86 × 10–9. The presence of indigenous microorganisms significantly reduced the risk of E. coli migration into water bodies and plants. The findings provide insights into the potential risk of biological pollution in soil, plants, and groundwater and offer a basis for control measures to reduce the survival of pathogens.