Effect Of Hydrogen On The Proliferation Mechanism Of Hydrogen-oxidizing Bacteria And The Transcriptomic Of Sinorhizobium Meliloti 1021 Strain

The nitrogen fixation process of legumes is accompanied by the release of hydrogen.Hydrogen can enter the surrounding soil and promote crop growth.In order to analyze the mechanism of hydrogen-oxidizing bacteria in legume rhizosphere microorganisms promoting plant growth,six strains of hydrogen-oxidizing bacteria isolated from soybean rhizosphere soil were treated with hydrogen and their growth-promoting characteristics were studied.In addition,transcriptome analysis was carried out on the Sinorhizobium meliloti 1021 before and after hydrogen treatment.By adjusting the parameters of the gas circulation culture system,five different concentrations of hydrogen were obtained and treated with SA-09 Aminobacterium,SA-17 Sinorhizobium meliloti,SA-08 Mycobacterium,SA-15 Pseudarthrobacter,SA-11 Mycobacterium SA-18Agromyces.The ability of hydrogen oxide was determined by gas chromatography.the results showed that all the six strains had the ability of hydrogen oxidation,but the ability of hydrogen oxidation was different,and the optimum concentration of hydrogen oxide was also different for each strain.The optimum hydrogen uptake concentration of strains SA-08,SA-09,SA-11 is 2.121 mmol·L^-1,the optimal hydrogen uptake concentration for strain SA-17 is 3.646 mmol·L^-1,and and that of strain SA-18 was 1.474 mmol·L^-1.The growth-promoting characteristics of 6 strains of hydrogen-oxidizing bacteria were studied.The results of ACC deaminase activity showed that ACC deaminase activity was detected in 5of 6 strains of hydrogen-oxidizing bacteria,but there were some differences in ACC deaminase activity.The ACC deaminase activity of the strains SA-17 and SA-15 was the strongest,both exceeding 40?mol/mg·h.The results of IAA secretion showed that all strains could secrete IAA,in the range of 8-30?g/m L,in which strain SA-17 was the strongest and strain SA-08 was the weakest.The results of secreting siderophore showed that all six strains were able to produce siderophore.SA-08,SA-09,SA-17 have a strong ability to secrete siderophore and the results of phosphorus solubilizing ability showed that SA-09 and SA-17had strong phosphorus solubilizing ability.In short,the results of the growth-promoting experiment show that the growth-promoting effect of hydrogen-oxidizing bacteria is the result of the synergistic action of many mechanisms.In order to analyze the mechanism of legume rhizosphere microorganisms promoting plant growth,S.meliloti 1021was treated with hydrogen and transcriptome analysis was carried out.The study showed that the total number of differentially expressed genes is 43 using twice as the threshold for screening differentially expressed genes.It accounts for 1.5%of the total annotated genes?2941?.Among them,39 genes were down-regulated and 4 genes were up-regulated.Hydrogen treatment changes the expression of genes related to aminobutyraldehyde dehydrogenase and cytochrome c oxidase,especially those involving amino acid metabolism and oxidative phosphorylation.These results may provide theoretical basis for more effective agricultural development of S.meliloti 1021.