Units of enzyme activity for nitrate reductase

The following table lists units of enzyme activity for nitrate reductase and fumarate reductase for a wild type and a mutant strain of Escherichia coli. fumarate reductase aerobic anaerobic Strain nitrate reductase aerobic anaerobiC NO3 NO3 NO3 NO3 +NO3 NO3 +NO3 NO3 K-12 80 12 1800 140 22 120 150 770 K-12(mut) 12 4 64 160 120 135 750 790 Identify the altered cell component for the mutant of E. coli K-12 and explain the phenotypic expression resulting from the mutation.