 The study identifies RNF as a key enzyme responsible for oxidizing ferrodoxin and reducing NAD during the succinate pathway into abundant bacteria of the rumin, prevetella brevis and prevetella ruminicula. This enzyme is important to propionate formation in these bacteria and may be used by many other bacteria from the environment. The study provides fundamental knowledge for manipulating fermentative propionate production. This article was authored by Bo Zhong, Christopher Linger, Hannah DeGruitt and others.