Moss-derived microbiome improves crop growth in lunar and Martian soil simulants

• Moss treatment improved soil properties, including available phosphorus and organic matter, enhancing barley growth. • Microbial community analysis identified Pseudomonas monteilii and Bacillus cereus as dominant, functionally beneficial strains. • Co-application of moss and these bacteria resulted in enhanced plant phenotypes and increased metabolite activity. • Metabolomic profiling of the moss-microbe systems showed upregulation of pathways in nucleotide biosynthesis and carbohydrate metabolism. This study evaluates the potential of a moss–microbe complex, composed of Hypnum plumaeforme and its associated microorganisms, as a bio-based biofertilizer for improving crop growth and soil quality. Beneficial microbial strains ( Pseudomonas monteilii and Bacillus cereus ) were isolated from the moss and selected based on key plant growth-promoting traits, including phosphate solubilization, indole-3-acetic acid (IAA) production, and siderophore synthesis. Using barley as a model crop, we assessed the effects of moss alone, microbes alone, and their combined application under extreme edaphic conditions represented by lunar (LHS) and Martian (MGS) soil simulants. The moss–microbe co-treatment significantly enhanced shoot biomass, dry weight, organic matter content, available phosphate, and cation exchange capacity (CEC). Notably, in MGS, where high bulk density and low porosity impeded microbial effectiveness, moss functioned as a biological buffer that facilitated microbial colonization and restored plant growth responses.16S rRNA profiling confirmed the stable presence of key genera, including Pseudomonas , Bacillus , and Devosia , in moss-treated soils. Metabolite profiling further revealed the significant accumulation of growth-related compounds such as D-ribose and D-gluconate, suggesting that the moss–microbe complex may reprogram rhizosphere metabolism. Collectively, these findings indicate that moss acts not merely as an organic input but as a key facilitator of plant–microbe interactions under harsh conditions. Our study demonstrates that the moss–microbe complex offers a sustainable and environmentally friendly biofertilizer strategy capable of simultaneously enhancing plant growth and soil functionality, with strong translational potential for land restoration, sustainable agriculture, and extraterrestrial farming.