Enteric pathogens from biofertilizer can accumulate in the soil, subsequently
contaminating water and crops. We evaluated the survival, percolation and leaching
of model enteric pathogens in clay and sandy soils after biofertilization with
swine digestate: PhiX-174, mengovirus (vMC0), Salmonella enterica Typhimurium and
Escherichia coli O157:H7 were used as biomarkers. The survival of vMC0 and PhiX-174
in clay soil was significantly lower than in sandy soil (ıPT90 values of 10.520 0.600
vs. 21.270 1.100 and 12.040 0.010 vs. 43.470 1.300, respectively) and PhiX-
174 showed faster percolation and leaching in sandy soil than clay soil (ıPT90 values of
0.46 and 2.43, respectively). S. enterica Typhimurium was percolated and inactivated
more slowly than E. coli O157:H7 (ıPT90 values of 9.340 0.200 vs. 6.620 0.500
and 11.900 0.900 vs. 10.750 0.900 in clay and sandy soils, respectively), such
that E. coli O157:H7 was transferred more quickly to the deeper layers of both soils
evaluated (percolation). Our findings suggest that E. coli O157:H7 may serve as a useful
microbial biomarker of depth contamination and leaching in clay and sandy soil and that
bacteriophage could be used as an indicator of enteric pathogen persistence. Our study
contributes to development of predictive models for enteric pathogen behavior in soils,
and for potential water and food contamination associated with biofertilization, useful for
risk management and mitigation in swine digestate recycling.
