| With the development of social economy and agriculture,demand for food is increasingly urgent,to meet the high and safe yield in agriculture,more and more people concerned about the issue that how to promote crop yield,and the rhizosphere bacteria brought hope for this problem.Hydrogen-oxidizing bacteria is a rhizosphere promoting bacteria,and has a wide variety.In order to screen and discover new hydrogen-oxidizing bacteria,to explore the basic characteristics of the hydrogen-oxidizing bacteria and find the effect' of growth-promoting,we make Alfalfa rhizosphere soil,which collect from Shanxi Province,as research material.the main contents include:Use the gas circulating culture system to produce H2 by electrolysis of water,with the incoming air to form a mixed gas,adjust the current size of the mixed gas in the device and control the flow of mixed gas in the 280mL/min,content of H2 is 832ppm.Use the mineral salt agar midium,that is,MSA medium,by adding sterile soil suspension in the culture medium,to ensure that the demand of trace elements for bacteria.In the inorganic environment,the Hydrogen-oxidizing bacteria can use hydrogen to fix the CO2 to obtain energy and carry out autotrophic growth.Therefore,more than 100 suspected strains of hydrogen-oxidizing bacteria were isolated by MSA medium.The TTC method and the ability of autotrophic feature detection were used to screen the hydrogen-oxidizing bacteria,Use the TTC method can detect the activity of the hydrogenase in the strain.16 strains of hydrogen-oxidizing bacteria were screened by these two methods:These strains contain strain 1-0-19,strain 1-1-2,strain 1-2-3,strain 1-2-9,strain 1-3-2,strain 3-0-15,strain 2-0-4,strain 3-1-17,Strain 2-1-4,strain 2-2-16,strain 2-3-1,strain 2-3-6,strain 2-3-8 strain 3-1-1,strain 3-3-7,strain 3-3-10.Select 16 strains of bacteria through morphological observation,Physiological and biochemical tests,and identification of 16 SrDNA.The results showed that 16 strains are belong to Ensifer,Cellulosimicrobium,Microbacterium,Arthrobacter,Nocardioides,Mycobacterium,Phyllobacterium,Isoptericola,Pseudoxanthomonas and Aeromicrobiums.Wheat grows experimental verification shows that hydrogen-oxidizing bacteria can been used to promote the growth of wheat seeds.The result shows the strain 1-0-19?1-1-2,1-2-3,1-2-9,1-3-2,2-0-4,2-1-4,2-2-16,2-3-1,3-6,3-0-15,3-1-1,3-1-17,3-3-7,3-3-10 each promote wheat roots increased by25%,79%,112%,122%,86%,49%,96%,31%,84%,102%,58%,111%,81%,128%,78%,100%;and the bud length increased by 42%,44%,27%,50%,69%,33%,55%,87%,71%,66%,86%,67%,73%,62%,73%,57%respectively;and the fresh weight increased by48%,59%,70%,82%,81%,75%,89%,103%,66%,55%,69%,59%,72%,59%,52%,59%respectively.It is proved that the isolated hydrogen-oxidizing bacteria have obvious promoting effect,and the promoting effect on root length is more obvious.In this paper,the changes of microbial community diversity in rhizosphere soils before and after hydrogen treatment were also studied.The result shows that the abundance of the species in the rhizosphere microbial community was changed after hydrogen treatment,and the abundance of the species in the sample was increased by the treatment of hydrogen,and the distribution of the species in the soil samples was even more uniform.The analysis of the experimental samples shows that there are larger differences between the first batch soil sample and the latter two batches soil samples,the reason may be due to that the first batch of sample collection time earlier,there is no nodules in the plant rhizosphere,And the second and third batches of samples were collected during the flowering time of Alfalfa,and the formation of rhizobia changed the species diversity of rhizosphere microorganisms. |
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