Effects of nitrate on methane production, fermentation, and microbial populations in in vitro ruminal cultures

► 12 μM reduced methane production by 70%, while not significantly decrease fermentation. ► Nitrate sustained its effect in reducing methane production in six consecutive cultures. ► Methanogens and F. succinogens did not adapt to the added nitrate, while Ruminococcus albus and R. flavefaciens did. ► Nitrate at 12 μM may be an alternative in reducing methane emission from cattle.