Fig. 4.

Relative expression levels of genes involved in nitrogen metabolism and concentrations of nitrogen compounds. a, b Relative expression levels of genes associated with nitrification and denitrification, respectively: left and right panels correspond to levels in reactors 1 and 2, respectively. Color-coded fractions indicate relative expression levels of individual transcript assemblies. c, d Changes in concentrations of ammonium and nitrate, respectively. Red and blue symbols indicate mean values of two measurements (n = 2) for reactors 1 and 2, respectively. Error bars denote ranges