Gut microbes regroup to aid defence after infection

Abstract

Resident gut microbes can help to block infection, but the mechanisms involved are not fully understood. It has now been found that changes in the microbial community after infection boost the level of a molecule that combats harmful bacteria.

Figure 1 |. How gut infection leads to changes that boost defence.

Stacy et al. report how infection by harmful bacteria such as Klebsiella pneumoniae in mice affects the resident gut bacteria. a, Klebsiella pneumonia can grow and establish an infection in the lumen of the mammalian gut, thanks to the enzyme cytochrome oxidase. This enzyme enables the bacterium to generate energy by aerobic respiration using oxygen in the host’s gut. b, After infection by K. pneumoniae, the level of the molecule taurine rises in the gut. Taurine is produced from the metabolism of bile acids, which are secreted into the gut from the liver. Stacy and colleagues present genetic evidence indicating that, after infection, resident bacteria that can use taurine become more common in the gut. When bacteria metabolize taurine, they produce hydrogen sulfide gas. c, Hydrogen sulfide inhibits aerobic respiration, and can thereby block the growth of harmful bacteria.