樟子松固沙林土壤可培养固氮细菌的群落结构

Community Structure of Cultivable Diazotrophic Bacteria in Soil of Sand-fixing Forest of Pinus sylvestris var. mongolica

为探明樟子松固沙林土壤中可培养固氮细菌的种类及其能力,丰富植物促生细菌菌种库,以传统纯培养方法筛选获得固氮菌株,基于16S rRNA基因,对其进行系统发育分析,并以靛酚蓝-分光光度法和钼锑抗比色法对所得菌株进行产氨和溶磷能力分析。结果表明,分离获得的12株固氮细菌以变形菌门、放线菌门和厚壁菌门3个门,6个科,7个属组成。变形菌门(50.0%)为优势门,Oxalobacteraceae(33.3%)和Microbacteriaceae(33.3%)为优势科,Curtobacterium(33.3%)为优势属。菌株的产氨能力在0.118~1.639 mg·L^-1之间,15-17、56-2、15-8和42-4菌株具有较强产氨能力,分别为1.639 mg·L^-1、1.470 mg·L^-1、1.301 mg·L^-1和1.132 mg·L^-1;有7株固氮细菌具有溶磷能力,36-5和30-3菌株均具有较强溶磷能力,分别为32.24 mg·L^-1和37.63 mg·L^-1。樟子松固沙林土壤蕴藏有多种固氮细菌,均有产氨能力且多数兼具溶磷能力,可作为植物生长促生细菌的重要来源。

In order to expound the abilities of cultivable diazotrophic bacteria in soil of sand-fixing forest of Pinus sylvestris var. mongolica and enrich the plant-promoting bacterial strains, the diazotrophic strains were screened by traditional pure culture method and the phylogenetic analysis was carried out based on 16 S rRNA gene. The ammonia production and phosphorus-solubilizing ability of the strains were analyzed by indophenol blue-spectrophotometry and molybdenum anti-colorimetric method, respectively. The results showed that the 12 stains were composed of Proteobacteria, Actinobacteria and Firmicutes. Proteobacteria(50.0%) was the dominant Phylum, Oxalobacteraceae(33.3%) and Microbacteriaceae(33.3%) were dominant families, and Curtobacterium(33.3%) was dominant genus. The ammonia production capacity of the strain was between 0.118 mg·L^-1 and 1.639 mg·L^-1, 15-17, 56-2, 15-8 and 42-4 strains had strong ammonia-producing ability, which were 1.639 mg·L^-1, 1.470 mg·L^-1, 1.301 mg·L^-1 and 1.132 mg·L^-1, respectively. 7 strains had phosphorus-solubilizing ability, 36-5 and 30-3 strains were stronger than the others which were 32.24 mg·L^-1 and 37.63 mg·L^-1, respectively. There are a variety of diazotrophic bacteria in soil of sand-fixing forest of Pinus sylvestris var. mongolica. They all have ammonia-producing ability and most of them have the ability to dissolve phosphorus. They can be used as an important source of plant growth-promoting bacteria.