ZOL 355 Lecture 11 Outline of Last Lecture I Antioxidant and redox regulation of gene transcription Outline of Current Lecture II Reactions of the Nitrogen cycle continued a Ammonification b Nitrification c Dentrification d Review III Environmental issues with Nitrogen Current Lecture II Reactions of the Nitrogen cycle continued a Ammonification i Production of ammonium from amino acids H R C COOH NH2 NH4 ii Conducted by decomposers Bacteria fungi i Extracellular enzymes initiate degradation of complex plant material into amino acids ii Yields energy b Nitrification i Production of nitrate ii NH4 NO2 NO3 energy iii Produces energy iv Energy is sufficient for synthesis of organic compounds from CO2 i Nitrification is a type of autotrophy called chemoautotrophy ii NO3 is then uptake and assimilated into biomass or dentrification c Dentrification i NO3 is used in anaerobic respiration ii Invoked when O2 low iii Requires C source for oxidation i Requires NO3 ii 4NO3 5C6H12O6 N2 CO2 4HCO3 3H2O energy iii This is common in water saturated agricultural soils because oxygen cant penetrate the soil and we have added fertile to these soils already i N2 fixation and denitrification should balance with regard to N2 but also the production of ammonium its conversion back to N2 a N2 NH4 a NH4 NO2 NO3 energy b 4NO3 5CH2O N2 CO2 4HCO3 3H2O energy d Review e N uptake plants bacteria and fungi uptake these compounds i NH4 amino acids NO3 amino acids urea amino acids f N2 fixation Only bacteria conduct N2 fixation i N2 NH4 amino acids proteins NH4 g Ammonification Amino acid Decomposition of amino acids by bacteria fungi Yields energy h Nitrification oxidation of NH4 yields energy for a type of autotrophy called chemoautotrophy i NH4 NO2 NO3 energy i Denitrification nitrate is used instead of oxygen for respiration Nitrate is reduced and organic compounds are oxidized i 4NO3 5C6H12O6 N2 CO2 4HCO3 3H2O energy III Environmental issues with Nitrogen a Haber had the first patent for commercial nitrogen use in 1918 and Bosch made it available for large scale production in 1913 b Since then the use of fertilizer increases grain production increases population increase energy usage increases meat production increases water usage and increases pesticide usage c Environmental Impacts of Increased N i Global warming via N2O production ii Decreases in terrestrial productivity iii Soil and lake acidification nitric acid HNO3 iv Harmful algal blooms v Degradation of sea grass coral vi Increased oxygen demands anoxia vii Changes in community structure