Background Soil salinization influences the physical and chemical properties of soil and disturbs soil biodiversity. Application of wheat straw in saline soils with enhance soil fertility could mitigate the effects of salinity on soil microbial properties under laboratory conditions. However, knowledge is inadequate regarding the effects of adding enriching plant residues with beneficial organisms on soil quality in saline soil. To enhance this knowledge, an incubation experiment was performed to evaluate the effect of wheat straw (0 and 1%, w/w) enriched with microbial strains (control, Streptomyces chartreusis, Pleurotus ostreatus and a mixture of P. ostreatus and S. chartreusis.) on some soil chemical and biochemical properties under salinity stress (0, 8 and 15 dS m−1). Results Salinity stress led to reducing soil available phosphorus (13–23%), available potassium (5–7%), total nitrogen (3–18%). Wheat straw inoculated with S. chartreusis and P. ostreatus improved microbial respiration rate (108–305%), soil microbial biomass carbon (80–110%), microbial biomass phosphorus (50–115%), catalase activity (20–140%), urease activity (25–45%), soil organic carbon (70–100%) and dissolved organic carbon (15–20%) under all salinity levels. The effect of S. chartreusis enriched wheat straw on enzymatic and microbial properties was higher than that of wheat straw inoculated with P. ostreatus under salinity stress conditions. Conclusions The results of this study demonstrated that the enrichment of wheat straw with S. chartreusis and P. ostreatus act synergistically and improve soil fertility and microbial properties. It can be concluded that the combined application of wheat straw and actinobacterial and fungal strain can be an effective strategy to ameliorate soil salinity stress in agriculture. Graphical Abstract

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