Azotobacters have been used as biofertilizer since more than a century. Azotobacters fix nitrogen aerobically, elaborate plant hormones, solubilize phosphates and also suppress phytopathogens or reduce their deleterious effect. Application of wild type Azotobacters results in better yield of cereals like corn, wheat, oat, barley, rice, pearl millet and sorghum, of oil seeds like mustard and sunflower, of vegetable crops like tomato, eggplant, carrot, chillies, onion, potato, beans and sugar beet, of fruits like mango and sugar cane, of fiber crops like jute and cotton and of tree like oak. In addition to the structural genes of the enzyme nitrogenase and of other accessory proteins, A. vinelandii chromosomes contain the regulatory genes nifL and nifA. NifA must bind upstream of the promoters of all nif operons for enabling their expression. NifL on activation by oxygen or ammonium, interacts with NifA and neutralizes it. Nitrogen fixation has been enhanced by deletion of nifL and by bringing nifA under the control of a constitutive promoter, resulting in a strain that continues to fix nitrogen in presence of urea fertilizer. Additional copies of nifH (the gene for the Fe-protein of nitrogenase) have been introduced into A. vinelandii, thereby augmenting nitrogen fixation. The urease gene complex ureABC has been deleted, the ammonia transport gene amtB has been disrupted and the expression of the glutamine synthase gene has been regulated to enhance urea and ammonia excretion. Gluconic acid has been produced by introducing the glucose dehydrogenase gene, resulting in enhanced solubilization of phosphate.

自一个多世纪以来，固氮细菌一直被用作生物肥料。固氮细菌需氧固定氮，精制植物激素，增溶磷酸盐，还抑制植物病原体或降低其有害作用。野生型固氮菌的施用可提高谷物（如玉米，小麦，燕麦，大麦，大米，珍珠粟和高粱），油料种子（如芥末和向日葵），蔬菜作物（如番茄，茄子，胡萝卜，辣椒，洋葱，马铃薯）的产量，豆子和甜菜，芒果和甘蔗等水果，黄麻和棉花等纤维作物以及橡树等树木。除了酶固氮酶和其他辅助蛋白的结构基因外，A。vinelandii染色体还包含调控基因。nifL和nifA。NifA必须在所有nif操纵子的启动子上游结合才能使其表达。NifL在被氧或铵激活后会与NifA相互作用并中和它。通过缺失nifL和将nifA置于组成型启动子的控制下，固氮作用得到了增强，从而导致在尿素肥料存在下能持续固氮的菌株。nifH（硝化酶铁蛋白的基因）的其他副本已被引入到A. vinelandii中，从而增强了固氮能力。尿素酶基因复合物ureABC已被删除，氨转运基因amtB已经破坏了谷氨酰胺合酶基因，并调节了谷氨酰胺合酶基因的表达以增强尿素和氨的排泄。葡萄糖酸是通过引入葡萄糖脱氢酶基因产生的，从而增强了磷酸盐的增溶作用。