Fig. 5. COMM treatment impacts nitrogen oxide reduction activity.

a Activity of nitrate and nitrite reductases with (red bars) or without (gray bars) COMM. One unit of activity represents 1 nmol nitrate/nitrate reduced per minute. Experiments were performed in triplicate and error bars represent SD. b NarGHI and NasDE differential abundance. The heat map displays average (n = 3 replicates) log₂-fold abundance changes of individual proteins across the different treatment conditions relative to the control (left-to-right: COMM, U, Al, Mn, Fe, Co, Cu, Cd, and Ni). The heat map scale (displayed at log₂-fold abundance changes relative to the control) is at the bottom of the image. The number of Fe atoms per protein was determined from their Bacillus subtilis (UP000001570) homologs (c) Relative changes in expression of narG, narH, and narI with (red bars) and without (gray bars) COMM exposure. Experiments were performed in triplicate and error bars represent ±SD. * p < 0.05, ** p < 0.01, *** p < 0.001.