A glimpse of Escherichia coli O157:H7 survival in soils from eastern China.

Escherichia coli O157:H7 (E. coli O157:H7) is an important food-borne pathogen, which continues to be a major public health concern worldwide. It is known that E. coli O157:H7 survive in soil environment might result in the contamination of fresh produce or water source. To investigate how the soils and their properties affect E. coli O157:H7 survival, we studied E. coli O157:H7 survival dynamics in 14 soils collected in eastern China from the warm-temperate zone to subtropical zone. Results showed that E. coli O157:H7 survival as a function of time can be well described by the Weibull model. The calculated td values (survival time to reach the detection limit, 100 colony forming units per gram oven-dried weight of soil) for the test soils were between 1.4 and 25.8 days. A significantly longer survival time (td) was observed in neutral or alkaline soils from north-eastern China (the warm-temperate zone) than that in acidic soils from south-eastern China (the subtropical zone). Distinct E. coli O157:H7 survival dynamics was related to soil properties. Stepwise multiple regression analysis revealed that the td values were significantly enhanced by soil microbial biomass carbon and total nitrogen, but were significantly reduced by amorphous Al2O3 and relative abundance of Chloroflexi. It should pay more attention to E. coli O157:H7 long survival in soils and its potential environmental contamination risk.