i) Experiment is carried out to test whether B. cereus or soil bacteria causing the denitrification. To carry out the experiment two test tubes with nutrient broth containing KNO3 are taken. Durham tubes are placed in both test tubes. In one tube B. cereus is inoculated and in other tube, soil suspension is inoculated. Both the tubes are incubated and then observed for denitrification. Denitrification is a 2 step process. In first step, nitrate is reduced to nitrite by enzyme nitrate reductase. Nitrite produced reacts with chemicals producing red color. In the second step, nitrite is reduced to liberate N2 gas by the activity of nitrite reductase enzyme. The gas bubble is formed in the Durham tube. The bacteria are checked for producing either one or both enzymes. If a bacterium is producing both enzymes, then gas bubble appears in Durhan tube. If onle one enzyme is produced, then red color precipitate is produced. By this, it is evident that denitrification is carried out by B. cereus or soil bacteria. ii) When there is excess nitrogen in the soil, it is accumulated and leached off into surface and ground waters. Consumption of water containing high nitrogen levels result in blue - baby syndrome in human infants. Excess nitrogen is toxic to the aquatic animals like amphibians and also toxic to pants and vegetation. Excess nitrogen in vegetation may cause potential health hazards in farm animals and livestock that feed on them. Solution i) Experiment is carried out to test whether B. cereus or soil bacteria causing the denitrification. To carry out the experiment two test tubes with nutrient broth containing KNO3 are taken. Durham tubes are placed in both test tubes. In one tube B. cereus is inoculated and in other tube, soil suspension is inoculated. Both the tubes are incubated and then observed for denitrification. Denitrification is a 2 step process. In first step, nitrate is reduced to nitrite by enzyme nitrate reductase. Nitrite produced reacts with chemicals producing red color. In the second step, nitrite is reduced to liberate N2 gas by the activity of nitrite reductase enzyme. The gas bubble is formed in the Durham tube. The bacteria are checked for producing either one or both enzymes. If a bacterium is producing both enzymes, then gas bubble appears in Durhan tube. If onle one enzyme is produced, then red color precipitate is produced. By this, it is evident that denitrification is carried out by B. cereus or soil bacteria. ii) When there is excess nitrogen in the soil, it is accumulated and leached off into surface and ground waters. Consumption of water containing high nitrogen levels result in blue - baby syndrome in human infants. Excess nitrogen is toxic to the aquatic animals like amphibians and also toxic to pants and vegetation. Excess nitrogen in vegetation may cause potential health hazards in farm animals and livestock that feed on them..

1. i) Experiment is carried out to test whether B. cereus or soil bacteria causing the denitrification.
To carry out the experiment two test tubes with nutrient broth containing KNO3 are taken.
Durham tubes are placed in both test tubes. In one tube B. cereus is inoculated and in other tube,
soil suspension is inoculated. Both the tubes are incubated and then observed for denitrification.
Denitrification is a 2 step process. In first step, nitrate is reduced to nitrite by enzyme nitrate
reductase. Nitrite produced reacts with chemicals producing red color. In the second step, nitrite
is reduced to liberate N2 gas by the activity of nitrite reductase enzyme. The gas bubble is
formed in the Durham tube. The bacteria are checked for producing either one or both enzymes.
If a bacterium is producing both enzymes, then gas bubble appears in Durhan tube. If onle one
enzyme is produced, then red color precipitate is produced. By this, it is evident that
denitrification is carried out by B. cereus or soil bacteria.
ii) When there is excess nitrogen in the soil, it is accumulated and leached off into surface and
ground waters. Consumption of water containing high nitrogen levels result in blue - baby
syndrome in human infants. Excess nitrogen is toxic to the aquatic animals like amphibians and
also toxic to pants and vegetation. Excess nitrogen in vegetation may cause potential health
hazards in farm animals and livestock that feed on them.
Solution
i) Experiment is carried out to test whether B. cereus or soil bacteria causing the denitrification.
To carry out the experiment two test tubes with nutrient broth containing KNO3 are taken.
Durham tubes are placed in both test tubes. In one tube B. cereus is inoculated and in other tube,
soil suspension is inoculated. Both the tubes are incubated and then observed for denitrification.
Denitrification is a 2 step process. In first step, nitrate is reduced to nitrite by enzyme nitrate
reductase. Nitrite produced reacts with chemicals producing red color. In the second step, nitrite
is reduced to liberate N2 gas by the activity of nitrite reductase enzyme. The gas bubble is
formed in the Durham tube. The bacteria are checked for producing either one or both enzymes.
If a bacterium is producing both enzymes, then gas bubble appears in Durhan tube. If onle one
enzyme is produced, then red color precipitate is produced. By this, it is evident that
denitrification is carried out by B. cereus or soil bacteria.
ii) When there is excess nitrogen in the soil, it is accumulated and leached off into surface and
ground waters. Consumption of water containing high nitrogen levels result in blue - baby
syndrome in human infants. Excess nitrogen is toxic to the aquatic animals like amphibians and
also toxic to pants and vegetation. Excess nitrogen in vegetation may cause potential health
hazards in farm animals and livestock that feed on them.