Effects of untreated dairy manure on soil microbiome

Biological soil amendments of animal origin (BSAAO) improve the soil health of agricultural fields for plant growth. However, as natural reservoirs for bacterial foodborne pathogens, BSAAO application can introduce and support microbes of public health concern, such as pathogenic Shiga toxin-producing Escherichia coli (STEC), in agricultural soils. Shiga toxin-producing E. coli (STEC), including E. coli O157:H7, is a major etiological agent of foodborne human disease outbreaks associated with fresh produce and can be transferred to produce via contaminated agricultural soil. Given the devastating impacts of foodborne STEC outbreaks on public health and growers , it is necessary to understand the longevity of the impacts of manure application on the pathogen risk in the soil as well as better understand the ecological and environmental conditions that contribute to STEC survival in the agricultural soil environment. Using shotgun metagenomic sequencing, this project investigated the microbiome of soil with and without BSAAO, focusing on STEC and the E. coli population over time alongside changes in the soil microbiome and soil abiotic properties. Two farms in Ohio, one using an untreated dairy manure amendment and one that does not use a BSAAO, were sampled for over a year for metagenomic analysis of the soil microbiome. This work expands upon the knowledge of conditions that support STEC persistence in the produce growing environment and its longevity following amendment, leading to improved guidelines and farming practices to prevent foodborne disease.