Isolation and Identification of Bacteria in Forest Rhizosphere Soil and Their Biological Activity Screening
[Objective]Functional strains with multiple biological activities were excavated from the forest rhizosphere soil of Wuliangshan National Nature Reserve,and their potential for development and application was explored.[Method]The 25 rhizosphere soil samples from different regions and plants in Wuliangshan National Nature Reserve were collected.The active strains with functions such as phosphate dissolution,nitrogen fixation,zinc dissolution,and antibacterial activity were isolated and identified using selective culture medium.The biological activities of these strains,such as secreted siderophore,ACC deaminase,and indoleacetic acid,were tested while verifying their effectiveness in promoting tomato seed germination and plant growth.[Result]70 phosphorus-dissolving bacteria,27 nitrogen-fixing bacteria,8 potassium-dissolving bacteria,and 51 antibacterial bacteria were isolated and identified.Among them,YIM B08401 and YIM B08402 were identified as Burkholderia alba and Pseudomonas qingdaonensis based on morphological,physiological,biochemical characteristics,and 16S rDNA sequencing.The two strains both had the activities of phosphate lysis,nitrogen fixation,zinc lysis and siderophore secretion.Their maximum soluble phosphorus content was(455.63±59.65)mg/L and(878.95±64.78)mg/L.The results of seed germination promotion tests of the two strains were similar,and the germination rates of the two strains were maintained at 82%-93%after applying the fermentation supernatant diluted 10 times,102 times and 103 times,which was significantly higher than 56%and 49%in the control group.The length of the treatment group with the fermentation liquid of the strain significantly increased compared with the blank control group.Pot experiment showed that the above ground length,fresh weight,dry weight,stem diameter,root length,fresh weight and dry weight of the two strains in the treatment group with the most obvious growth promotion effect were significantly better than that in the control group.Compared with the control group,the above indexes of YIM B08401 significantly increased by 89%,495%,268%,62%,53%,385%and 469%,and the above indexes of YIM B08402 significantly increased by 118%,528%and 477%,55%,37%,413%and 747%,respectively.In addition,strain YIM B08401 also had activities of antagonizing pathogenic bacteria and secreting ACC deaminase,and YIM B08402 also had the activity of secreting indoleacetic acid.[Conclusion]The rhizosphere soil in the forest of Wuliang National Nature Reserves contained a variety of strains with biological activity.B.alba YIM B08401 and P.qingdaonensis YIM B08402 demonstrates the potential for the development and application of new microbial fertilizers.
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