Analysis the Diversity of the rhizosphere microorganisms from Helichrysum arenarium(L.)Moench. and Screening of Growth-promoting Bacteria in Xinjiang, China

Rhizosphere microorganisms can utilize nutrient resources in the rhizosphere efficiently, while rhizosphere growth-promoting bacteria play a crucial role in regulating soil fertility and promoting plant health. In this study, we employed a combination of isolation, purification, identification of dominant microorganisms, and high-throughput sequencing technology to analyze the main microbial groups and diversity in the rhizosphere soil of Helichrysum arenarium（L.）Moench. in Altay, Xinjiang，China. By isolating bacterial strains from the rhizosphere soil using a dilution coating method, we successfully obtained 43 strains. Subsequently, selective medium was utilized to screen for growth-promoting characteristics among these isolated strains from the rhizosphere soil of H. arenarium（L.）Moench.. The results obtained through high-throughput amplification sequencing revealed that the rhizosphere soil harbored diverse bacterial communities belonging to 35 phyla, 93 orders, 215 families, 324 genera and 231 species associated with H. arenarium（L.）Moench., as well as fungal communities consisting of 14 phyla ,47 orders ,96 families ,204 genera and 571 species. Among these bacterial communities identified, eight phyla exhibited relative abundances exceeding 1%, with Actinobacteriota being most predominant at an abundance rate of 41.30%. Additionally,five bacterial genera were found to have relative abundances exceeding 1% ,with Arenimicrobium_luteum being most abundant at 6.11% . Furthermore,four fungal phyla displayed relative abundances surpassing1 % ,with Ascomycota accounting for 67.21% of total fungal community composition.Finally,four fungal genera demonstrated relative abundances higher than 1% ,with Knufia representing 3.80% of total fungal community composition.The analysis on culturable bacteria's promotion activity within the rhizospheric soil indicated that two strains,S16and S29, exhibited the highest solubility index for inorganic phosphorus. However, it lacked the ability to dissolve organophosphorus and potassium. On the other hand, strains S7 and S10, which were screened, demonstrated nitrogen-fixing capabilities. Nine strains with excellent iron-bearing capacity were identified, with strain S16 exhibiting the highest D/d value and strongest iron-bearing capacity among them. Our findings revealed that 43 rhizosphere soil bacteria belonged to three genera. The ten growth-promoting bacteria were identified as Kocuria rosea, Priestia megaterium, Bacillus mobilis, B. bataviensis, B. mycoides (two strains), B. paramobilis, and Alcaligenes faecalis. This study provides a particular research basis for the influence of H. arenarium（L.）Moench. rhizosphere microorganisms on soil nutrient release and depicts a solution for improving the yield and quality cultivation of H. arenarium（L.）Moench. by isolating, screening, and identifying rhizosphere soil growth-promoting bacteria, including screening strains with growth-promoting functions and analyzing the population structure of rhizosphere and habitat soil in combination with high-throughput sequencing technology.