Screening And Identification Of Soil Functional Bacteria In The Sandstone Area Of Ordos

The Ordos sandstone area is located in the hilly area of Inner Mongolia Plateau,and the natural conditions are very bad.The freez-thaw erosion,wind erosion and rain erosion of the soil in this area are increasing year by year,the ecological environment is deteriorating,soil erosion is serious,and the ecosystem becomes fragile,which are extremely detrimental to local economic development and environmental protection.Soil microbes are important components in the ecosystem.They not only participate in the decomposition of organic matter,the circulation of nutrients,the improvement of soil structure,but also reserve nutrients for above-ground vegetation,promote nutrient absorption of plants,increase plant resistance,and provide favorable conditions for plant diversity.As a key link in the process of material circulation,soil microbes play an important role in improving the soil properties of the sandstone area,rebuilding the soil microbial system and restoring the ecosystem of the sandstone area.In order to obtain microbial active strains with potential application and good environmental affinity,this paper uses the selective medium to separate and screen soil microbes in the Ordos City of Inner Mongolia Autonomous Region.The detection method was used to determine the ability of the strain,and the excellent strains with good growth were screened out,and the strains were identified according to the morphological characteristics,physiological characteristics and 16 S rDNA sequence analysis of the strains.The main results are as follows:1.A total of 51 strains of phosphate solubilizing bacteria,18 strains of nitrogen-fixing bacteria,16 strains of photosynthetic bacteria and 27 strains of halophilic bacteria were initially screened.Morphological observation showed that the colony form of the phosphate solubilizing bacteria was round opaque,moist and smooth,with protrusions and yellowish color;the colony forms of nitrogen-fixing bacteria were mostly round and dry,smooth surface,rough edges,light blue,light yellow,etc.The colony morphology of photosynthetic bacteria were mostly round,smooth and shiny,and the edges were neat and viscous.The colony forms of halophilic bacteria are mostly round and dull,with neat edges,beige and beige.2.The strains obtained by the primary screening were further rescreened,and 3 strains of nitrogen-fixing bacteria,3 strains of photosynthetic bacteria,3 strains of halophilic bacteria and 10 strains of phosphate-dissolving bacteria with strong phosphate-dissolving activity were selected,among which RP-Z-1.RP-L-14 and RP-D-10 strains had the strongest phosphate-dissolving activity,which were 216.62 ?g/mL,124.53 ?g/mL,and 130.75 ?g/mL,respectively.3.16 S rDNA sequence identification identified excellent strains,all phosphate solubilizing bacteria and photosynthetic bacteria are Bacillus,Nitrogen-fixing bacteria including Agrobacterium and Sphingomonas zeicaulis,The strains of salt bacteria include Brevibacterium sp.and Bacillus.4.The phosphate-dissolving bacteria,nitrogen-fixing bacteria,photosynthetic bacteria and halophilic bacteria obtained by screening can effectively promote seed germination.Some strains have excellent phosphorus-dissolving ability and salt-tolerant alkalinity,and can be as the reserve of dominant functional bacteria strains used as microbial fertilizer for ecological restoration in arsenic sandstone area.