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【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 [ABSTRACT FROM AUTHOR]

To collect and directionally explore siderophore-producing microorganisms, the siderophore-producing microorganisms in the native forest soil of the Ailao Mountain were screened, isolated, and identified using the pure culture method. Combined with the high-throughput sequencing results of soil internal transcribed spacer (ITS) amplicons, the position of active strains in the community structure was anchored. The relationship between active strains and environmental factors was analyzed further. The results showed that all of the active siderophore-producing fungal strains screened and isolated from the Ailao Mountain valley and the original forest soils through pure culture were Ascomycetes, which belonged to Aspergillus, Penicillium, Metarhizium, Trichoderma, Talaromyces, and Beauveria. These microorganisms were mainly isolated from high altitude virgin forest areas, in which most of the soil samples had high organic matter content, high water content, low pH value, and low ferrous content. Combined with the ITS high-throughput sequencing results, the above active strains all had the corresponding operational taxonomic units (OTUs). The results of the OTUs-environmental factor analysis showed that the Penicillium strains were significantly positively correlated with organic matter content; Aspergillus strains were significantly positively correlated with pH value but had a significant negative correlation with altitude and soil water content; Trichoderma and Talaromyces strains had not significantly correlated with all environmental factors; the distribution of Beauveria and Metarhizium had certain positive correlation with pH value. Thus, it is proposed that the primitive forest environment has a selective impact on the microorganisms. The siderophore-producing Ascomycetes from the primitive forest are important functional resources worthy of further exploration and may play an important role in the circulation of soil minerals and organic matter formation. [ABSTRACT FROM AUTHOR]