5-8 Nitrate Reduction Experiment

To identify bacteria that produces the enzyme nitrate reductase, which reduces nitrate to nitrite.

Nitrate reduction is used by organism capable of this metabolic pathway:

denitrification, allowing them to use nitrate as an electron acceptor in the absence of oxygen.

Write out the chemical reaction for single step nitrate reduction

Nitrate (NO3-) is reduced to nitrite (NO2-)

Why are we adding reagents nitrate-A-A and nitrate B ? A change to a red color after reagent A & B are added to indicate what chemical reaction

,indicates the presence of nitrite, confirming that nitrate was reduced to nitrite.

Why do plants like nitrogen fixing bacteria ?

Plants benefit from nitrogen-fixing bacteria because these microbes convert atmospheric nitrogen into ammonia, which plants can utilize for growth and development.

What molecule is the Durham tube detecting in This experiement

The Durham tube detects the production of gas, typically nitrogen gas (N₂) or other gaseous byproducts from the reduction of nitrate.

Explain how zinic is used in tthis experiment. What reaction dies it catalyze

Zinc is used in this experiment to reduce nitrate to nitrite. It catalyzes the reduction reaction, allowing for the detection of nitrate presence by releasing a red color when reagents are added.

A change to red color after the addition of zinic indicates what explain below

The addition of zinc powder to the sample reveals that nitrate was reduced to nitrite, which subsequently gets reduced further to nitrogen gas. A red color change confirms that nitrate is present in the sample before reduction, indicating the end product is nitrogen gas.

If you get a clear result after adding reagents A and B, then describe 2 different results that may be possible

A clear result may indicate that nitrate was not reduced at all, or that it was reduced beyond nitrite to nitrogen gas. In both cases, further testing is needed to confirm the specific reduction outcome.

List 2 Genera which are capble of denitratification. The genera that you listed are commonly associated with which enviroment

Pseudomonas and Bacillus; commonly found in soil and aquatic environments.

What was the name of the genus+species of the organism that you tested positive for denitrification

The genus and species of the organism tested positive for denitrification was Pseudomonas aeruginosa, which is commonly found in soil and aquatic environments.

An organism postive for single step nitrate reduction will turn the media what color after chemical nitrate A & B are added

red after the addition of reagents A and B.

An organism postive for denitrification will turn the media color after chemicals Nitrate A & B & Zinic added

red or pink, indicating nitrate reduction to nitrite or nitrogen gas.

Write out the chemical reaction for denitrification make sure to label all of the molecules involved

Denitrification involves the reduction of nitrate (NO3-) to nitrogen gas (N2), typically through intermediate nitrite (NO2-). The overall reaction can be represented as: 2 NO3- + 10 e- + 12 H+ → N2 + 6 H2O.