Homework answers / question archive / An aerobic soil bacterium, strain CZA14, was inoculated onto a minimal-medium agar plate containing glucose, potassium phosphate, NaCl, MgSO4, FeSO4 and KN03 (as sole nitrogen source)

An aerobic soil bacterium, strain CZA14, was inoculated onto a minimal-medium agar plate containing glucose, potassium phosphate, NaCl, MgSO4, FeSO4 and KN03 (as sole nitrogen source)

Biology

Share With

An aerobic soil bacterium, strain CZA14, was inoculated onto a minimal-medium agar plate containing glucose, potassium phosphate, NaCl, MgSO4, FeSO4 and KN03 (as sole nitrogen source). CZA14 was also stab inoculated into nutrient agar (a rich medium) containing added KN03 in a sterile universal for the nitrate reductase test. The two cultures were incubated at 30°C for 7 days and then examined. CZAM had grown well on the minimal medium with KN03 as the sole nitrogen source. It had also grown well in the nutrient agar, but the test for nitrate reduction showed that the nitrate in this medium had not been reduced to nitrite. How do you explain these, apparently contradictory, observations about nitrate reduction by this strain?