Richter Taylor K S, Kauffman Michael, Mammel Mark K, Lacher David W, Rajashekara Gireesh, Leonard Susan R
Office of Applied Microbiology and Technology, Human Foods Program, U.S. Food and Drug Administration, Laurel, Maryland, USA.
Department of Animal Sciences, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Wooster, Ohio, USA.
Appl Environ Microbiol. 2025 Aug 7:e0044725. doi: 10.1128/aem.00447-25.
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 (STEC), in agricultural soils. Using shotgun metagenomic sequencing, this project investigated the microbiome of soil with and without BSAAO, focusing on STEC and the 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. All manure samples were positive for genes, indicating the presence of STEC. Impacts of the manure on the soil lasted four weeks by several measures including higher diversity and more frequent STEC detection. Outside of these four weeks post-amendment, Shiga toxin genes () were identified periodically in both fields throughout the year. STEC detection significantly correlated with higher O-serogroup diversity, as well as lower soil cation exchange capacity and concentrations of calcium, magnesium, and organic nitrogen. Differential abundance analysis of the soil metagenomes identified several taxa influenced by amendment but did not identify taxa correlated with detection of genes. This work provides insights into the timing of and ecological factors associated with STEC persistence in the agricultural environment.IMPORTANCEShiga toxin-producing (STEC), including 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. This work expands upon the knowledge of conditions that support STEC persistence in the produce-growing environment and its longevity following amendment in commercial fields with naturally occurring STEC contamination.
动物源生物性土壤改良剂（BSAAO）可改善农田土壤健康状况，促进植物生长。然而，作为细菌性食源性病原体的天然宿主，施用BSAAO会在农业土壤中引入并支持一些关乎公众健康的微生物，例如产志贺毒素致病性大肠杆菌（STEC）。本项目采用鸟枪法宏基因组测序技术，研究了施用和未施用BSAAO的土壤微生物群落，重点关注STEC及其随时间变化的种群情况，以及土壤微生物群落和土壤非生物特性的变化。对俄亥俄州的两个农场进行了为期一年多的采样，其中一个农场使用未经处理的奶牛粪便改良剂，另一个不使用BSAAO，对土壤微生物群落进行宏基因组分析。所有粪便样本的志贺毒素基因均呈阳性，表明存在STEC。通过多种指标衡量，粪便对土壤的影响持续了四周，包括更高的多样性和更频繁地检测到STEC。在改良后的这四周之外，全年两个田地中均定期检测到志贺毒素基因（stx）。STEC的检测与更高的O血清型多样性以及更低的土壤阳离子交换容量、钙、镁和有机氮浓度显著相关。对土壤宏基因组的差异丰度分析确定了几个受改良影响的分类群，但未确定与stx基因检测相关的分类群。这项工作为农业环境中STEC持久性的时间和相关生态因素提供了见解。
重要性
产志贺毒素致病性大肠杆菌（STEC），包括O157:H7，是与新鲜农产品相关的食源性人类疾病暴发的主要病原体，可通过受污染的农业土壤转移到农产品上。鉴于食源性STEC暴发对公众健康和种植者造成的毁灭性影响，有必要了解施用粪肥对土壤中病原体风险的影响持续时间，并更好地了解有助于STEC在农业土壤环境中存活的生态和环境条件。这项工作扩展了对支持STEC在农产品种植环境中持久性的条件及其在商业田地中自然存在STEC污染后改良后的持续时间的认识。
