Melamine, the chemical that achieved infamy in 2008 for the poisoning of children's milk in China, owes its toxicity in part to gut bacteria.

Wei Jia and Aihua Zhao of Shanghai Jiao Tong University in China and their group show that the toxicity of melamine in rats is reduced and its excretion increased if gut microbes are suppressed with antibiotics. They also show that the bacterium Klebsiella terrigena, which the authors had cultured from rat faeces, converts melamine to cyanuric acid in vitro. This acid — which forms crystals with melamine — is a key component of the kidney stones linked to both melamine-related kidney failure and death.

The authors suggest that melamine toxicity may depend on the composition of an organism's gut microbes.

Sci. Transl. Med. 5, 172ra22 (2013)