Ingestion of Remediated Lead-contaminated Soils Affects the Fecal Microbiome of Mice

The relationship between ingestion of diets amended with a Pb-contaminated soil and the composition of the fecal microbiome was examined in a mouse model. Mice consumed diets amended with a Pb-contaminated soil in its native (untreated) state or after treatment for remediation with phosphoric acid or triple superphosphate alone or in combination with iron-waste material or biosolids compost. Subacute dietary exposure of mice receiving treated soil resulted in modulation of the fecal intestinal flora, which coincided with reduced relative Pb bioavailability in the bone, blood and kidney and differences in Pb speciation compared to untreated soil. Shifts in the relative abundance of several phyla including Verrucomicrobia, Tenericutes, Firmicutes, Proteobacteria, and TM7 (Candidatus Saccharibacteria) were observed. Because the phyla persist in the presence of Pb, it is probable that they are resistant to Pb. This may enable members of the phyla to bind and limit Pb uptake in the intestine. Families Ruminococcaceae, Lachnospiraceae, Erysipelotrichaceae, Verrucomicrobiaceae, Prevotellaceae, Lactobacilaceae, and Bacteroidaceae, which have been linked to health or disease, also were modulated. This study is the first to explore the relationship between the murine fecal microbiome and ingested Pb contaminated soils treated with different remediation options designed to reduce bioavailability. Identifying commonalities in the microbiome that are correlated with more positive health outcomes may serve as biomarkers to assist in the selection of remediation approaches that are more effective and pose less risk.