| Hydrogen-oxidizing bacteria,as a type of bacteria that depend on the release of H2 from symbiotic nitrogen fixation in leguminous plants,have extremely high research value.In this paper,soybean rhizosphere soil was used as the research object,and the mineral salt culture medium was used to separate and purify the hydrogen-oxidizing bacteria in the soybean rhizosphere using a modified gas circulating culture system.Hydrogen peroxide was detected by gas chromatograph to screen the hydrogen-oxidizing bacteria.The strains selected by strain morphological characteristics,physiological and biochemical tests,and 16 S r DNA identification.At the same time,the growth-promoting characteristics of the selected strains were determined,the ability of the strain to secrete IAA was measured by the Salkowski reagent method,and the iron-producing carrier strains were screened by the double-layer CAS plate method.In this paper,high-throughput sequencing technology was used to study the effects of bacterial community structure in soybean rhizosphere at different growth stages.The experimental results are as follows:A gas circulation culture system was used to electrolyze water to generate H2,and the pumped air was mixed to adjust the current so that the concentration of H2 in the mixed gas was 832 ppm so that the flow rate of the mixed gas was 280 m L/min.The soil suspension diluted with a concentration gradient was coated on a mineral salt culture medium using a coating plate method to isolate strains,and 75 strains were isolated by separation and purification.The ability of the isolated strains to perform hydrogen oxidation was determined by gas chromatography.After testing,14 strains with strong hydrogen oxidation ability were selected: strain 01-8,strain 1-15,strain 1-17,strain 3-17,Strain 3-18,strain 5-3,strain 5-13,strain 5-15,strain 101-2,strain 101-13,strain 201-7,strain 201-17,strain 201-9 and strain 1-18.The hydrogen consumption value of these 14 strains of hydrogen oxidizing bacteria was 1041.66-2769.23 ppm.Among them,there were 3 strains with hydrogen absorption values greater than 2000 ppm,which were strains of 1-18 to 2769.23 ppm,strains of 3-18 to 2541.67 ppm,and strains of 5-3 to 2741.67 ppm.Through the morphological,physiological and biochemical characteristics and 16 Sr DNA strain identification of the 14 strains,the results showed that the 14 strains of hydrogen oxidizing bacteria belong to Mycobacterium,Pseudarthrobacter sulfonivorans,Sinorhizobium Synrhizobium,Agromyces,Rhodococcus,Arthrobacter,Aminobacter.The growth-promoting characteristics of 14 strains were studied.The results showed that all strains could secrete IAA with a secretion capacity of 7-51 ?g/m L.Among them,strain 1-18 had the strongest secretion capacity,the concentration was 50.184 ?g/m L,strain 01-8.The secretion capacity was the worst,with a concentration was 7.146 ?g/m L;10 strains could secrete siderophores,but their ability to secrete iron carriers was different.It was demonstrated that the selected hydrogen oxidizing bacteria had one or more promoting properties,indicating that the hydrogenated bacteria in soybean rhizosphere had a certain research value.The effect of different growth periods on the bacterial community structure in soybean rhizosphere was studied.The results showed that the bacteria with high rhizosphere abundance in Soybean included Proteobacteria,Actinomyces,and Acidobacteria.The abundance of species in the rhizosphere microbial communities will change during different growth stages,and the diversity of bacterial community structure during the mature period is higher than that of the seedling stage. |
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