ETD

• hydroxyapatite nanoparticles
• maize
• microbial biofertilisers
• phosphorus
• phosphorus‑solubilising bacteria

The limited bioavailability of soil phosphorus (P) highlights the need for sustainable management strategies based on microbial biofertilisers. In this study, native phosphorus‑solubilising bacteria (PSBs) were isolated from long‑term tillage experiments conducted in three climatic regions—Arid (Niger), Continental (Austria), and Mediterranean (Spain)—under conventional and no‑tillage systems. Isolates were obtained on tricalcium phosphate medium and characterised for P solubilisation, biological nitrogen fixation, and indole‑3‑acetic acid production. Molecular identification was performed by 16S rRNA sequencing.
The best-performing strains were assessed for their ability to solubilise P from salmon‑derived nano‑hydroxyapatite (nHAs) and subsequently validated in maize pot experiments using site‑specific consortia. Fifty‑nine PSBs were isolated overall, predominantly belonging to the genera Priestia, Sinorhizobium, Streptomyces, and Bacillus. Continental strains exhibited the highest solubilisation indices, whereas Mediterranean strains showed the greatest mobilisation of P from nHAs. Pot trials revealed site‑specific effects of PSB inoculation and SnHA fertilisation, with significant interactions on plant growth and nutrient uptake.
Overall, the results demonstrate the potential of native PSBs, particularly when combined with nanofertilisers, to improve P use efficiency.