Ecotoxicology inside the gut: impact of heavy metals on the mouse microbiome - PubMed (original) (raw)

Ecotoxicology inside the gut: impact of heavy metals on the mouse microbiome

Jérôme Breton et al. BMC Pharmacol Toxicol. 2013.

Abstract

Background: The gut microbiota is critical for intestinal homeostasis. Recent studies have revealed the links between different types of dysbiosis and diseases inside and outside the intestine. Environmental exposure to pollutants (such as heavy metals) can also impair various physiological functions for good health. Here, we studied the impact of up to 8 weeks of oral lead and cadmium ingestion on the composition of the murine intestinal microbiome.

Results: Pyrosequencing of 16S RNA sequences revealed minor but specific changes in bacterial commensal communities (at both family and genus levels) following oral exposure to the heavy metals, with notably low numbers of Lachnospiraceae and high numbers levels of Lactobacillaceae and Erysipelotrichaceacae (mainly due to changes in Turicibacter spp), relative to control animals.

Conclusions: Non-absorbed heavy metals have a direct impact on the gut microbiota. In turn, this may impact the alimentary tract and overall gut homeostasis. Our results may enable more accurate assessment of the risk of intestinal disease associated with heavy metal ingestion.

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Figures

Figure 1

Figure 1

DGGE profiles revealed microbial diversity in the cecum content and fecal pellets of mice exposed for 8 weeks to Cd and Pb salts via their drinking water. The figure shows DGGE gels of the V5-V6 hypervariable 16S rDNA region, illustrating the microbiota’s composition in the cecum and the feces of 4 mice treated (or not) with 20 mg L-1 (ppm) of Cd or 100 mg L-1 (ppm) of Pb.

Figure 2

Figure 2

An unweighted pair group method with arithmetic mean tree of the same gels. Pairwise similarities were calculated with BioNumerics software (version 6.6.4), using a Dice coefficient with 0% optimization, 0.3664% fixed tolerance, exclusion of uncertain bands and no relaxed doublet matching, fuzzy logic or area sensitivity.

Figure 3

Figure 3

Distribution of bacterial phylotypes in the cecum content and fecal pellets of mice exposed for 8 weeks to Cd (20 or 100 ppm) or Pb (100 or 500 ppm) salts via their drinking water. 16S rRNA-base analyses were derived from 454/Roche multitag pyrosequencing. Data are expressed as the mean percentage abundance of the total assignment (n = 5 animals per group). In line with the literature data, most of the bacteria in untreated (control) mice belonged to Firmicutes or the Bacteroidetes, whereas Actinobacteria were very rare.

Figure 4

Figure 4

Distribution of bacterial subgroups in the cecum content and fecal pellets of mice exposed for 8 weeks to Cd (20 or 100 mg L -1 ) or Pb (100 or 500 mg L -1 ) salts via their drinking water. (A) Family-level and (B) genus-level. 16S rRNA-base analyses were derived from 454/Roche multitag pyrosequencing. Data are expressed as the mean percentage abundance (n = 5 animals per group). Only operational taxonomic units (OTU’s) present in dominant families (> 0.1%) were considered. *: p < 0.05 and **: p < 0.01: significantly different from the control group (water with no added Cd or Pb) for the corresponding taxa. The color code is defined in the inset on the right of the Figure.

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