Expt 28: ANAEROBIC RESPIRATION: NITRATE REDUCTION
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15 terms
Terms | Definitions |
|---|---|
 Anaerobic respiration | produces some energy sulfate, carbonate or nitrate is final electron acceptor |
| microorganisms use nitrate in the soil | to process hydrogen produced in respiration |
| denitrification | series of reactions that reduce nitrate to dinitrogen gas |
| denitrification | depletes nitrogen from the soil |
| crop rotation, composting, grow legumes (with nitrifying bacteria) | maintain balance of nitrogen |
| nitrate reduction test | inoculate tubes of nitrate broth with durham tubes to demonstrate gas production |
| products of nitrate reduction | NH3, N2, N2O, NO2-, NO3- |
| Test for ammonia (NH3) | odor |
| Test for N2 and N2O | gas bubbles in Durham tube |
| Test for NO2- | add few drops of alpha-naphthylamine acetate + sulfanilic acid (red color = positive) |
| Test for NO3- | presence of NO3- indicates organism did not reduce nitrate -add Zn++ to tubes with no color change or bubbles |
| Zn++ reacts with NO3- | reduce it to NO2- NO2- reacts with alpha-naphthylamine acetate + sulfanilic acid already present to give red color |
| E coli positive for | NO2- and NO3- |
| Paracoccus denitrificans positive for | N2 and N2O gases |
| no gas, no color change after zinc is added | the products of reduction could not be determined by our tests |
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