Evaluating E. Coli contamination effects on lettuce growth and assessing the impact of heavy metals on bacterial viability in water, plant, and soil

Abstract

Despite the continuous awareness of food safety and improvements in sanitary infrastructure, foodborne illnesses continue to burden public health significantly. Numerous research studies have shown the occurrence of foodborne outbreaks linked to Escherichia coli contamination in fresh produce. In Lebanon, specifically within the Litani River Basin (LRB), investigations have reported high levels of both E. coli and Heavy Metals (HM) in the water. This is particularly concerning given that the agricultural sector in Lebanon relies on this water source for irrigation. This study aimed to shed light on food safety issues concerning romaine lettuce within the basin. We explored the occurrence of E. coli in water soil and lettuce and evaluated the influence of different irrigation systems on the level of E. coli contamination. We also focused on examining the impact of four HM (Manganese (Mn), Copper (Cu), Zinc (Zn), and Nickel (Ni)) on the behavior of three E. coli strains isolated from water, soil, and lettuce by evaluating the growth of the bacteria under varying concentrations of HM after 10 hours and 20 hours of treatment. Additionally, we assessed their antibiotic resistance. We found that LRB was highly contaminated with E. coli. To cope with that contamination, the hydroponic system was the best system to mitigate the lettuce contamination. In addition, distinct responses to HM exposure were revealed. By highlighting the significance of agriculture in this area, especially in economically challenged regions, the study raises awareness of contamination occurrences and transmission pathways. It seeks to propose a better understanding of the situation, with suggestions for optimizing agricultural practices in association with environmental sustainability and food safety standards within the LRB.