Parisa Mohammadi

Bioleaching is a prominent method among eco-friendly techniques. The efficiency of bioleaching is reduced by the presence of brackish water. Moreover, it has been reported that the most successful bioleaching systems are those that include both autotrophic and heterotrophic microorganismes. This research focuses on enhancing uranium bioleaching in brackish waters using the halotolerant bacterium Acidithiobacillus ferrooxidans strain THA4 and the fungus Rhodotorula toruloides strain IR-1395. The experimental data were modeled by the Response Surface Methodology (RSM) approach. The suggested model for uranium extraction in a brackish environment using microorganisms demonstrated an alignment with the experimental data, with a correlation coefficient of R₂ = 0.94. The results showed that the amount of uranium bioleaching by the consortium increased by 24.22%, compared to the bacterium alone under the optimal conditions suggested by the software. The study employed SEM–EDS to investigate the morphological changes in ore samples exposed to the microorganisms. The findings offer insights into the relationship dynamics between acidophilic bacteria and heterotrophic yeasts in uranium bioleaching of brackish waters. Finally, this study has improved biohydrometallurgical methods for uranium extraction from low-grade ores, especially in saline and low-resources conditions.

Phototrophic microorganisms, particularly cyanobacteria, are involved in biogeochemical cycles that alter the environment. They participate in processes such as bioweathering and biomineralization on various substrates, specifically carbonate rocks. This study investigates the interactions of phototrophic biofilms with the limestone substrate of Pasargadae, the UNESCO World Heritage Site in Iran. The initial survey revealed bedrock alterations including microfracturing, detachment, and localized mineral dissolution related to phototrophic biofilms. Further analyses showed the dominance of cyanobacteria, particularly Chroococcidiopsis spp., in endolithic biofilms. Six months of laboratory experiments with inoculation of limestone samples with Chroococcidiopsis sp., under controlled hydration-desiccation regimes and various constant humidities (29.5–100% RH) were conducted. The results demonstrated the formation of rhombohedral crystals of CaCO ₃ by Chroococcidiopsis sp., on limestone samples in the hydration-dessication period and 100% humidity. The present study links cyanobacterial activity to carbonate dissolution-precipitation dynamics and rock bioweathering in the semiarid region of Pasargadae. In addition, these findings highlight the crucial role of water availability in biofilm-driven weathering of calcium carbonate. Further research is needed to clarify microbial community-level interactions.

Preservation of ancient works is one of the most important concerns of those interested in cultural heritage. Restorers use various physicochemical and biological methods to preserve and/or clean ancient objects. One of the cleaning methods is using herbal essential oils (EOs). Since EOs are often volatile, their incorporation into polymers can mitigate this drawback. Here, the antimicrobial properties of Thymus vulgaris EO were evaluated through the disk diffusion method against microbial strains, which had been isolated from our previous work. To reduce its volatility, two commercial polymers, alginate and polyvinyl alcohol, were used, and their antimicrobial properties were evaluated. Next, the tests were done on tile models. The results showed that the EO was effective against all selected microbial strains. Furthermore, alginate hydrogel containing EO showed the best antimicrobial activity, suggesting its potential as an effective cleaning method. Further investigation is necessary to ensure that this hydrogel has no undesirable impacts on historical substrates.

Background: Aerobic vaginitis (AV) is a type of genital infection, which affects women's health. Aerobic vaginitis was first identified as a cause of genital infection in 2002. The most common bacteria associated with aerobic vaginitis in previous studies were Enterococcus faecalis, Escherichia coli, Staphylococcus aureus and coagulase-negative Staphylococci. Materials and Methods: A total ...

Background: Paper substrates are highly susceptible to fungal degradation, as fungi produce enzymes that decompose paper materials. This study investigates and compares the antifungal efficacy of silver nanoparticles (AgNPs) synthesized through various physical and biological methods. The fungal strains tested, Penicillium sp. and Aspergillus sp., were isolated from paper samples in a previous study, chosen for their more prevalence in contaminated paper. Methods: Five types of AgNPs, synthesized using both biological and physical methods, were evaluated. The biological methods involved the use of extracts from Juglans regia green husk, Malva sylvestris leaves, and cyanobacterial cells. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the AgNPs were determined using standard protocols. Results: The MIC values of the AgNPs synthesized from different sources exhibited varying degrees of antifungal activity against the tested fungi. The AgNPs’ effectiveness ranked as follows: (1) AgNPs produced by Nostoc pruniforme, (2) AgNPs produced by M. sylvestris, (3) AgNPs produced by Nostoc IBRC-M5064, (4) AgNPs produced by J. regia, and (5) physically synthesized AgNPs. Conclusion: These findings highlight the potential of biologically synthesized AgNPs as environmentally friendly biocidal agents for preventing and controlling paper biodegradation.