Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on Microbial Gut Communities
Principal Investigator:	Dr. Syed Hashsham, Department of Civil & Environmental Engineering
Research Assistant:	Prianca Bhaduri
Funding Agency:	NIEHS - Superfund

Microbial gut communities dynamically change in response to factors such as diet, onset of disease, and external stressors. We evaluated the effect of the environmental contaminant, TCDD on the microbial gut communities in mice. Female C57BL/6 mice were treated daily for 4 consecutive days with 7.5 µg/kg TCDD or sesame oil vehicle (intraperitoneal and gavage) and sacrificed 7 days after the first dose; fecal and intestinal samples (duodenum, jejunum, ileum and colon) were collected and analyzed for differences in the microbial community using 454 and Illumina sequencing. In addition to the 16S rRNA based analysis, functional microbiome was also analyzed using a novel MySelect based approach that included more than 1000 functional gene targets.

Analysis of the microbial communities of the duodenal samples by 454 pyrosequencing of the 16S rRNA revealed that TCDD-treated mice possessed higher levels of Escherichia/Shigella and Ruminococcacea, and members of the Clostridiales. There was also reduction in diversity including loss of populations like Lactobacillus in the treated samples. Clostridia are among the main populations implicated in the conversion of choline to trimethylamine (TMA) and mice with TCDD-induced fatty liver show decreased levels of urinary TMA levels.