第32章 生物固氮
第32章 生物固氮
自然界中的氮循环( The Nitrogen Cycle) by some anaerobic bacteria Amino acids nd other reduced synthesis in nitrogen-carbon plante and microorganisms degradation by animals and Ammonia anIsms Nitrate NO NHA nitrogen fixation by some bacterin (e. g, Klebsiella, Azotobacter Rhizobium) nitrification nitrifcation by soil bacteria by sod bacteria Nitrite Figure 21-1 NO2 of nitrogen fix 10 kg The total amount of nitrogen fixed annually in the biosphere exceeds 10kg
自然界中的氮循环（The Nitrogen Cycle ） The total amount of nitrogen fixed annually in the biosphere exceeds 1011 kg
固氮生物 共生型固 豆科植物的根瘤菌 氮微生物 非豆科植物(木麻黄属) 固氮 的根瘤菌 微生物 厌氧的巴氏梭菌,需氧固氮菌, 自生型固 厌氧和光合自养的蓝藻,需氧 氮微生物 和光合自养的细菌
固氮生物 固氮 微生物 共生型固 氮微生物 自生型固 氮微生物 豆科植物的根瘤菌 非豆科植物(木麻黄属) 的根瘤菌 厌氧的巴氏梭菌, 需氧固氮菌, 厌氧和光合自养的蓝藻,需氧 和光合自养的细菌
Cyanobacteria and rhizobia can fix n2 into armonia R leguminous ian
Cyanobacteria and Rhizobia can fix N2 into ammonia Rhizobia exist in nodules of leguminous plants
固氮反应 The reduction of n2 to NH3 is thermodynamically favorable no+3Ho-2NH 4G 0=-335kJ/mol But kinetically unfavorable: the bond energy for the triple bond in n2 is 942 kJ/mol oN+8H+ +8e +16ATP+16H,-> 2NH3+H2+16ADP+16P;
固氮反应 •N2 + 8H+ +8e - + 16ATP + 16H2O → • 2NH3 + H2 + 16ADP + 16Pi The reduction of N2 to NH3 is thermodynamically favorable : • N2 + 3H2 → 2NH3 G` o=-33.5kJ/mol But kinetically unfavorable: the bond energy for the triple bond in N2 is 942 kJ/mol