NITRATE REDUCTION TEST
1. Consider the unincoulated tube. Is it a positive or negative control? What information is provided by the unincoluted tube?
2. Suppose you remove your test cultures form the incubator and notice that one of them, a known fermenter, has a gas bubble in the Durham tube. Knowing that fermenters frequently produce gas, you ignore the bubble and proceed to the next step. Adding reagents produces no change, and neither does adding zinc. Is this occurrence consistent with denitrification? Why?
CATALASE TEST
3. Soldier the step in the tube where hydrogen peroxide is added to the uninoculated tube. Is this a positive or negative control? what information is provided by the results?