高寒地区燕麦根际联合固氮菌研究 Ι固氮菌分离及鉴定

Associative nitrogen-fixing bacteria in the rhizosphere of Avena sativa in an alpine region Ⅰ Isolation and identification

结合气相色谱仪,利用乙炔还原等方法对高寒地区重要饲用植物——燕麦(Avenasativa)根际联合固氮菌进行了分离和鉴定。结果表明,该地区燕麦根际联合固氮菌株较少(8株),菌株分布以根系表面(RP)最多,根表土壤(RS)次之,距根系较远的土壤(NRS)和根内(HP)最少,即:RP>RS>NRS≥HP;菌株固氮酶活性相差较大(C2H4112.5～1147.9nmol/mL·h),具有较高固氮酶活性的菌株较少(C2H4大于500nmol/mL·h只有2株);菌株均为革兰氏阴性菌,经鉴定分属Azotobacter(3株)、Pseudomonas(3株)和Azospirillus(2株)3个属。相对于其它生境和植物,高寒地区燕麦根际联合固氮菌种类较为单一。

This study isolates and identifies associative nitrogen-fixing bacteria (ANB) from the rhizosphere of Avena sativa in an alpine region by acetylene reduction assay (ARA) combined with gas chromatography (GC). Eight ANB strains were found. Strain distribution was related to root proximity,with the majority found on the root surface (RP), followed by those within soil by roots (RS), soil away from roots (NRS), and the least found within roots (HP). Nitrogenase activity showed large variation between strains (C2H4 112.5-(1 147.9) nmol/mL·h). Only 2 strains showed nitrogenase activity higher than C2H4 500 nmol/mL·h. All the strains obtained were gram-negative, and belonged to Azotobacter (3 strains), Pseudomonas (3 strains) and Azospirillus (2 strains) genera. The ANB species found in the rhizosphere of A.sativa in this alpine region are relatively few compared with other plants and habitats.