A microbiologist studying the normal human microbiome isolates bacteria that cannot grow when exposed to oxygen. From which of the following body sites would these bacteria most likely originate?

Escherichia coli commonly inhabits the intestinal tract of cattle and other warm‑blooded animals. During food processing, contamination can occur if intestinal contents contact edible tissue. Which type of food is therefore most frequently associated with outbreaks of E. coli food poisoning?

A strain of Escherichia coli isolated from a patient with bloody diarrhea is found to produce a cytotoxin that closely resembles the Shiga toxin produced by Shigella dysenteriae. Which category of E. coli is most consistent with this finding?

During a microbiology lecture on the gut microbiome, a professor explains that microbial biomass contributes significantly to the solid content of human feces. Approximately what percentage of the dry weight of fecal material is typically bacterial cells?

Which statement best defines the human gut microbiome in the context of modern microbiology?