禾本科草坪草固氮菌株筛选及部分特性初步研究

Isolation and Characteristics of Nitrogen Fixation Bacteria in Rhizosphere of Turfgrass

从西安和兰州两地多年生禾本科草坪草根际分离到固氮菌株302株,通过气相色谱仪,利用乙炔还原法最终筛选出10个固氮酶活性较高的菌株.研究发现,菌株X4固氮酶活性最高,达180.20 nmol C2H4/h*ml,与其他菌株相比差异极显著(P<0.01),L9最小为37.78 nmol C2H4/h*ml.比较西安和兰州两地多年生草地的固氮酶活性,西安地区不同草地的差异较大,最高者是最低者的4.5倍左右.单从固氮酶活性来看,西安地区草地有开发潜力的优良菌株相对较多,如X4和X1,而兰州地区的相对较少.分离到的固氮菌70%都有溶磷能力,溶磷圈直径比(D/d)在1.044～2.729之间,其中L7菌株溶解有机磷和无机磷能力相对较好,X1和L5溶解无机磷的能力相对较好,X4和X2溶解有机磷较好.菌株大部分都有分泌生长素能力,但差异较大,分泌IAA浓度最高的是X2,达22.3mg/L,其次为X3菌株.

The 302 nitrogen fixtion srains were isolated from the Rhizosphere of turfgrass in Xi＇an and Lanzhou. And ten strains which had the higher positive nitrogenase activity were selected for further study. The results showed that the nitrogenase activity of X4 strain was the higest （180. 20 nmol C2H4/h·ml） and was significantly different from other strains, while strain L9 was the least （37.78 nmol C2H4/h·ml）. The nitrogenase activity of strains isolated from Xi＇an varied greatly compared with that of Lanzhou. The maximum was about 4.5 times of the mimmum. There were many good strains which had such potential such as X4 and X1 in Xi＇an only in consideration of nitrogenase activity. But few strains with such ability were isolated from Lanzhou. Seventy percent of nitrogen fixation bacteria had the ability to solubilize phosphorus. The value of D/d Varied from 1. 044 to 2. 729. Strain L17 in the aspect of dissolving organic and inorganic phosphorus was better than other strains. Strains X15 and L5 could dissolve inorganic phosphorus, and X4 and X2 resolved organic phosphorus well. Sixty percent of strains had the ability to produce IAA, but had significantly difference. The highest content of IAA produced was up to 22.3 mg/L. Strain X3 was second.