Tetrathionate broth is an enrichment medium. Initially, when a mixed bacterial stool sample is inoculated into this medium, the bacteria respire aerobically. Once O₂ is depleted, most bacteria switch to fermentation in order to continue growth. However, Salmonella can use the tetrathionate in this medium as a terminal electron acceptor, so can grow anaerobically. Why does this give the bacteria a competitive advantage over other bacteria in the sample?

Question

Tetrathionate broth is an enrichment medium. Initially, when a mixed bacterial stool sample is inoculated into this medium, the bacteria respire aerobically. Once O₂ is depleted, most bacteria switch to fermentation in order to continue growth. However, Salmonella can use the tetrathionate in this medium as a terminal electron acceptor, so can grow anaerobically. Why does this give the bacteria a competitive advantage over other bacteria in the sample?

Quizplus · Accepted Answer

Anaerobic respiration, such as that performed by Salmonella using tetrathionate as a terminal electron acceptor, yields more ATP than fermentation. This allows Salmonella to grow more efficiently in the absence of oxygen compared to other bacteria that must rely on fermentation, giving it a competitive advantage.

Tetrathionate Broth Is an Enrichment Medium