| The proposal of green agriculture makes microbial fertilizer become more concerned,and hydrogen-oxidizing bacteria which can promote the growth of plants are gradually studied.In this paper,the rhizosphere soil of soybean containing HUP-in Shaanxi Qinhan New District was used as the material to explore the suitable hydrogen concentration for the innoculation of hydrogen-oxidizing bacteria;after that,the difference in the growth of plants by hydrogen-oxidizing bacteria under different hydrogen concentration conditions were preliminary investigated;the isolated bacteria were identified by physiological and biochemical characteristics and 16S rDNA,and more hydrogen-oxidizing bacteria were hope to found on the basis of the existing ones,the main results were as follows:The dual integrated regulators of the H2 treatment system had indices of 12,18 and 24,respectively,to produce different concentrations of hydrogen,which were mixed with the air.The conditions for the gas chromatography were that the temperature of TG-BOND Msieve 5A GC chromatographic column was 50°C and TCD detector was 200°C,split ratio at 15:1.Under these conditions,the hydrogen concentration produced by the H2treatment system was determined to be 11300 ppm,12900 ppm and 13500 ppm,respectively.The rhizospheric soil of the soybean was collected,and the soil sample was treated with air and different concentrations of hydrogen to analysis the soil respiration intensity,pH,catalase,dehydrogenase and urease activity,and the changes in microbial community diversity.The results showed that compared with the air treated soil samples,the respiration intensity decreased in soil samples treated with different concentrations of hydrogen;pH increased significantly,in which the pH of the soil sample treated with12900 ppm H2 was the highest;the catalase activity of the soil sample was significantly increased;the dehydrogenase activity was significantly reduced;the urease activity was decreased of the soil sample treating with the hydrogen concentration of 13500 ppm,and the urease enzyme activity of the soil samples treated with the other two hydrogen concentrations was reversed;compared with air-treated soil samples,the abundance of Proteobacteria increased and the abundance of Actinobacteria decreased after treatment with a hydrogen concentration of 12900 ppm,after treatment with hydrogen concentrations of 11300 ppm and 13500 ppm,the abundance of Proteobacteria decreased,the abundance of Actinobacteria increased.Comprehensive analysis of soil properties and changes in microbial diversity,it was concluded that the hydrogen concentration of 12900 ppm was more suitable for the isolation of hydrogen-oxidizing bacteria.Soil sample treated with 12900 ppm hydrogen was spread onto mineral salt agar?MSA?in petri plates containing no carbon,and the suspected hydrogen-oxidizing bacteria were isolated.6 hydrogen-oxidizing bacteria were screened from suspected strains by autotrophic ability test and hydrogen utilization test.By morphological observation,physiological and biochemical tests and 16S rDNA,2 of the 6 hydrogen-oxidizing bacteria belong to Arthrobacter,while the other 4 belong to Agromyces,Rhodococcus,Isoptericola and Microbacterium,respectively.The ability of phosphate-solubilizing capacity and produce iron carriers at different hydrogen concentrations was determined.The results showed that:?1?only strain 2-1-9had phosphate-solubilizing capacity when air-treatd,and at the hydrogen concentration of12900 ppm,the phosphate-solubilizing capacity of strains 2-1-9,3-1-6 and 3-1-10increased,and the ability from large to small was 2-1-9,3-1-10,3-1-6;?2?in the case of air,on the fifth day of adding thechrome azurol S,strains 2-3-1,2-2-13 and 3-1-10 produced a yellow halo;the hydrogen concentration was 12900 ppm,on the fifth day of the addition of the chrome azurol S,the halo diameter of strains 2-3-1,2-2-13 and 3-1-10 decreased;on the fourth day of the addition of the dye,strains 2-1-9 and 3-1-6 produced a halo.Strain2-1-9 and 3-1-6 can effectively utilize phosphorus and iron which are not easily utilized in the environment under the condition of 12900 ppm of hydrogen. |
PDF Full Text Request