Against the background of increasing salinisation of land, the use of environmentally friendly plant growth-promoting bacteria (PGPB) resources for soil improvement is particularly important. The aim of this study was to investigate the effects of Pseudomonas cedrina DY1-3 on maize seedling growth, soil physico-chemical properties, and bacterial community structure. The study also evaluates the effects of this microbial agent on plant growth and saline soil improvement, providing theoretical references for microbial agents in promoting plant growth and improving saline soils. We found that there were significant differences between arable and saline soils in terms of soil physico-chemical properties and bacterial community structural composition, and that total salt was the main environmental factor influencing microbial communities. In both arable and saline soils, the application of DY1-3 bacterial suspension had a significant positive effect on the growth of maize plants and bacterial community richness. In arable soil, it could promote the growth of maize seedlings and significantly increase the Shannon and Simpson index, and AK was a key factor influencing the bacterial community. In saline soil, it could alleviate the mitigation stress and promote the growth of maize seedlings and cause a significant increase in Shannon’s and Chao1 index, and the application of DY1-3 and potting could cause a significant decrease in total salt. In addition, DY1-3 and maize plants acting together in the soil can better improve the saline soil. The above results indicate that DY1-3 has potential for saline soil improvement and crop yield enhancement.

Introduction: Endohyphal bacteria are microorganisms that inhabit fungal hyphae or reproductive structures, which influence fungal physiology and contribute to broader ecosystem processes. However, current knowledge regarding endohyphal bacteria associated with oil-producing fungi in arid environments remains scarce and warrants further investigation. Method: Oil-producing fungi were isolated and screened from arid soil samples collected in Toksun County, Xinjiang, China. A preliminary assessment of the presence of endohyphal bacteria within these fungi was conducted using SYTO 9 green fluorescent staining. High-throughput sequencing was employed to analyze the distribution patterns and community composition of the endohyphal bacteria. Results: Endohyphal bacteria were detected in 16 fungal strains, which constituted 61.5% of the total 26 oil-producing strains obtained. High-throughput sequencing analysis identified 63 amplicon sequence variants (ASVs) belonging to 6 phyla and 35 genera, with Proteobacteria representing the dominant phylum. Most fungi contained multiple endohyphal bacterial taxa and exhibited pronounced interspecific variation in community composition. Functional prediction analysis indicated a significant enrichment of pathways related to metabolism, environmental information processing, and genetic information processing in the endohyphal bacteria associated with distinct fungal hosts. Discussion: Oil-producing fungi may establish interactive systems through symbiotic associations with diverse endohyphal bacteria. These symbiotic interactions may promote lipid accumulation and enhance ecological adaptability in oil-producing fungi, potentially mediated by the metabolic synergy and functional complementarity described above. In conclusion, this study provides a preliminary characterization of the diversity and community structure of endohyphal bacteria associated with oil-producing fungi in arid environments, establishing a basis for future investigations into their functional interactions.