Biofertilizers are a key component of organic agriculture. Bacterial biofertilizers enhance plant growth through a variety of mechanisms, including soil compound mobilization and phosphate solubilizing bacteria (PSB), which convert insoluble phosphorus to plant-available forms. This specificity of PSB allows them to be used as biofertilizers in order to increase P availability, which is an immobile element in the soil. The objective of our study is to assess the capacity of PSB strains isolated from phosphate solid sludge to solubilize three forms of inorganic phosphates: tricalcium phosphate (Ca₃(PO₄)₂), aluminum phosphate (AlPO₄), and iron phosphate (FePO₄), in order to select efficient solubilization strains and use them as biofertilizers in any type of soil, either acidic or calcareous soil. Nine strains were selected and they were evaluated for their ability to dissolve phosphate in the National Botanical Research Institute’s Phosphate (NBRIP) medium with each form of phosphate (Ca₃(PO₄)₂, AlPO₄, and FePO₄) as the sole source of phosphorus. The phosphate solubilizing activity was assessed by the vanadate-molybdate method. All the strains tested showed significantly (p ≤ 0.05) the ability to solubilize the three different forms of phosphates, with a variation between strains, and all strains solubilized Ca₃(PO₄)₂ more than FePO₄ and AlPO₄.

Control of green mold, caused by Penicillium digitatum, by fungicides raises several problems, such as emergence of resistant pathogens, as well as concerns about the environment and consumers’ health. As potential alternatives, the effects of chitosan on green mold disease and the quality attributes of citrus fruits were investigated. Fruits were wounded then treated with different concentrations of chitosan 24 h before their inoculation with P. digitatum. The results of in vitro experiment demonstrated that the antifungal activity against P. digitatum was improved in concert to the increase of chitosan concentration. In an in vivo study, green mold was significantly reduced by chitosan treatments. In parallel, chitinase and glucanase activities were enhanced in coated fruits. Evidence suggested that effects of chitosan coating on green mold of mandarin fruits might be related to its fungitoxic properties against the pathogen and/or the elicitation of biochemical defense responses in coated fruits. Further, quality attributes including fruit firmness, surface color, juice content, and total soluble solids, were not affected by chitosan during storage. Moreover, the loss of weight was even less pronounced in chitosan-coated fruit.

The Trichoderma fungal species and the bacteria Bacillus species were described as inducers of plant systemic resistance in relation to their antagonistic activity. The objective of this study was to evaluate the effect of selected strains of Bacillus amyloliquefaciens (I3) and Trichoderma harzianum (A) on inducing systemic resistance in Arabidopsis thaliana as a model for plant molecular genetics. The microorganisms were identified and were confirmed for their antagonistic potential in vitro and in vivo in previous studies. In order to explore this mechanism, two mutants of A. thaliana carrying a PR1 promoter (a conventional marker of salicylic acid (SA) pathway) and LOX2 promoter (a marker triggering jasmonic acid (JA) pathway activation) were analyzed after inoculating antagonists. Transgenic reporter line analysis demonstrated that B. amyloliquefaciens I3 and T. harzianum A induce A. thaliana defense pathways by activating SA and JA at a high level compared to lines treated with chemical elicitors of references (acibenzolar-S-methyl (Bion 50 WG (water-dispersible granule)), SA, and methyl jasmonate). The efficacy of B. amyloliquefaciens I3 and T. harzianum A in inducing the defense mechanism in A. thaliana was demonstrated in this study.

Septoria tritici blotch, caused by the fungal pathogen Zymoseptoria tritici, is a highly significant disease on wheat crops worldwide. The objective of the present study was to find out new bacterial strains with bio-antimicrobial activity against Z. tritici. Two phyllospheric bacteria (S1 and S6) were isolated from wheat ears and identified as Bacillus velezensis strains according to 16S rRNA Sanger sequencing. Antagonistic assays performed with either living strains or cell-free culture filtrates showed significant in vitro antifungal activities against Z. tritici. For the culture filtrates, the half-maximal inhibitory dilution and the minimal inhibitory dilution were 1.4% and 3.7% for the strain S1, and 7.4% and 15% for the strain S6, respectively. MALDI—ToF analysis revealed that both strains synthesize cyclic lipopeptides but from different families. Interestingly, only strain S1 produces putative bacillomycin D. Such differential lipopeptide production patterns might explain the difference observed between the antifungal activity of the culture filtrates of the two strains. This study allows the identification of new lipopeptide-producing strains of B. velezensis with a high potential of application for the biocontrol of Z. tritici.

Phosphogypsum (PG), a calcium sulfate-rich byproduct of phosphate fertilizer production, is generated in vast quantities worldwide and represents a major environmental management challenge. At the same time, its chemical composition makes PG a potentially valuable soil amendment, particularly for the reclamation of saline, sodic, and acidic soils. This review critically synthesizes current knowledge on PG generation processes, physicochemical properties, agronomic performance, and associated environmental and health risks. Evidence from peer-reviewed studies demonstrates that appropriately managed PG applications can improve soil structure, enhance water infiltration, reduce sodium toxicity, alleviate aluminum stress, and increase crop productivity. However, PG contains variable levels of impurities, including heavy metals and naturally occurring radionuclides, which raise concerns regarding soil contamination, groundwater pollution, food safety, and human health, especially under high or repeated application rates. Regulatory frameworks governing PG use differ substantially between regions, reflecting inconsistencies in waste classification, radiological thresholds, and leaching criteria. This review highlights key knowledge gaps related to contaminant mobility, bioavailability, and long-term ecological impacts and discusses mitigation strategies such as purification, controlled application rates, and integrated regulatory oversight. By balancing agronomic benefits against environmental risks, this work provides a comprehensive framework for the safe valorization of phosphogypsum in agriculture, supporting sustainable land management and circular economy objectives.