 Lactococcus lactis is a lactic acid bacterium that can use oxygen as an extracellular electron acceptor or ferricionide. When this bacterium is blocked from using NAD+, it can use ferricionide instead. This allows the bacteria to survive under conditions where oxygen is present but not available to them. Additionally, when these bacteria are exposed to ferricionide, they become rod-shaped and their acid resistance increases. Furthermore, by using adaptive laboratory evolution, researchers were able to increase the ability of the bacteria to use ferricionide. This could have implications for food fermentation and microbiome engineering, as ferricionide respiration can reduce oxidative stress, promote growth of oxygen-sensitive microorganisms, and shape microbial communities. This article was authored by Liu Yang and Ji Yu, Shinchin Xiao, Ji Yi Zhao, and others.