固氮根瘤菌ORS571泌铵型突变株的筛选和接种盆栽小麦试验

Isolation of NH_4^+-Excreting Mutants of Azorhizobium Caulinodans ORS571 and Its Inoculation Experiment on Potted Wheat

以固氮根瘤菌ORS571为出发菌株,经过亚硝基胍(NTG)诱变,以对乙二胺的抗性为初筛指标,得到一株编号Ac-92的抗乙二胺的泌铵效果较高的突变株。由于向胞外分泌铵,该突变株在培养基上菌落非常小,而且不如原始菌株光滑。其固氮酶活性是原始菌株的1/5,在无氮半固体培养基上培养5和7d时其在培养基中的泌铵量分别为3.131和3.917mmol/L。经过15N同位素稀释法盆栽植物试验,与对照相比,该突变株由于存在其他缺陷,不能给植物提供更多的氮素营养。

The start strain Azorhizobium caulinodans ORS571 was treated by nitrosoguanidine（NTG） and mutants resistant to ethylenediamine were selected, a serial number Ac- 92 ethylenediamine-resistant mutant strain was screenedj exhibiting NH4^＋ - Excreting obviously. The mutant colony on the culture medium was very small because of the characteristic of excreting NH4^＋ out of its cell. Furthermore colony is less slimy than the original strain. The nitrogenase activity of Ac - 92 was only one fifth of its w tS ld strain. When incubating for 5 and 7 days on the nitrogen-free semi-solid substrate , the amount of NH4^＋ excreted into the medium was 3. 131 and 3. 917mmol/L separately. Potted crops were measured by the method of ^15N isotope dilution techniques. Compared to the control,the mutant of Ac - 92 could not supply more nitrogen nutrition to the potted plants due to some deficient property.