Enrico Doria

Plant-based biostimulants (PBs), agents rich in bioactive compounds, are emerging as key players able to sustainably improve plant growth and crop productivity to address food security. PBs are generally applied as foliar spray or soil irrigation, while more recently, the application as seed priming treatments is being envisaged as a highly sustainable method to also improve seed quality and germination. Therefore, this review proposes to explore the use of PBs for the seeds industry, specifically discussing about the relevance of product market values, sustainable methods for their production, why and how PBs are used for seed priming, and pinpointing specific strengths and challenges. The collected research studies indicate that PBs applied to seeds result in improved germination, seedling growth, and stress tolerance, although the molecular mechanisms at work are still largely overlooked. The high variability of bioactive molecules and used sources point towards a huge reservoir of nature-based solutions in support of sustainable agriculture practices.

The aim of this study was to evaluate the potential of Aspergillus tubingensis in extracting metals from rocks simulating Martian regolith through biomining. The results indicated that the fungal strain produced organic acids, particularly oxalic acid, in the first five days, leading to a rapid reduction in the pH of the culture medium. This acidic medium is ideal for bioleaching, a process that employs acidolysis and complexolysis to extract metals from rocks. Additionally, the strain synthesized siderophores, molecules capable of mobilizing metals from solid matrices, as verified by the blue CAS colorimetric test. The secretion of siderophores in the culture medium proved advantageous for biomining. The siderophores facilitated the leaching of metal ions, such as manganese, from the rock matrix into the acidified water solution. In addition, the susceptibility of the Martian regolith simulant to the biomining process was assessed by determining the particle size distribution, acid composition after treatment, and geochemical composition of the rock. Although the preliminary results demonstrate successful manganese extraction, further research is required to optimize the extraction technique. To conclude, the A. tubingensis strain exhibits promising abilities in extracting metals from rocks through biomining. Its use could prove useful in future in situ mining operations and environmental remediation efforts. Further research is required to optimize the process and evaluate its feasibility on a larger scale.