Escherichia coliO157 survival in liquid culture and artificial soil microcosms with variable pH, humic acid and clay content

Aims This research was performed to investigate the influence of clay and humic acid onEscherichia coliO157 survival in model soils. Additionally, the influence of pH and humic acid onE. coliO157 in liquid culture was investigated. Methods and Results Artificial soil microcosms were prepared with sand, kaolinite, bentonite and humic acid. Artificial soil microcosms pH was adjusted (6 center dot 0-7 center dot 0) with aluminium sulphate beforeE. coliO157 inoculation. After 56 days of incubation at 30 degrees C, significant differences inE. coliO157 log CFU per gram were observed between 0 and 1000 ppm (P < 0 center dot 0001) and 0 and 5000 ppm (P < 0 center dot 0001) humic acid in 1 center dot 5% clay soils, but not in 7 center dot 5 or 15% clay soils. Significant differences (P < 0 center dot 05) inE. coliO157 log CFU per ml were observed in liquid culture influenced by humic acid concentrations after 8 h at 37 degrees C. Conclusions The developed model soils supportE. coliO157 populations over 28 days, and higher clay soils may aid inE. coliO157 survival. Significance and Impact of the Study These results provide insights into physicochemical properties of soil that may influenceE. coliO157 in the environment and help explainE. coliO157 survival in various soils and geographical regions.

Automated summary

This research investigated the influence of clay and humic acid on Escherichia coli O157 survival in model soils, finding that higher clay content in soils may aid in the survival of the bacteria.