It is known that the presence of sulfate decreases the methane yield in the anaerobic digestion systems. Sulfate-reducing bacteria can convert sulfate to hydrogen sulfide competing with methanogens for substrates such as H₂ and acetate. The present work aims to elucidate the microbial interactions in biogas production and assess the effectiveness of electron-conductive materials in restoring methane production after exposure to high sulfate concentrations. The addition of magnetite led to a higher methane content in the biogas and a sharp decrease in the level of hydrogen sulfide, indicating its beneficial effects. Furthermore, the rate of volatile fatty acid consumption increased, especially for butyrate, propionate, and acetate. Genome-centric metagenomics was performed to explore the main microbial interactions. The interaction between methanogens and sulfate-reducing bacteria was found to be both competitive and cooperative, depending on the methanogenic class. Microbial species assigned to the Methanosarcina genus increased in relative abundance after magnetite addition together with the butyrate oxidizing syntrophic partners, in particular belonging to the Syntrophomonas genus. Additionally, Ruminococcus sp. DTU98 and other species assigned to the Chloroflexi phylum were positively correlated to the presence of sulfate-reducing bacteria, suggesting DIET-based interactions. In conclusion, this study provides new insights into the application of magnetite to enhance the anaerobic digestion performance by removing hydrogen sulfide, fostering DIET-based syntrophic microbial interactions, and unraveling the intricate interplay of competitive and cooperative interactions between methanogens and sulfate-reducing bacteria, influenced by the specific methanogenic group.

Unveiling the Temporal Aspect of MRI Tattoo Reactions: A Prospective Evaluation of a Newly-Acquired Tattoo with Multiple MRI Scans - Article abstract #943411

Chronic wound infections are frequently associated with bacterial biofilms, which significantly reduce the efficacy of antimicrobial treatments. Conventional in vitro evaluation methods, such as disc diffusion assays and static biofilm models, lack physiological relevance, whereas more advanced wound models are often costly, complex, and difficult to reproduce. In this study, we present a cost-effective and easily applicable in vitro wound model based on gelatin–alginate hydrogels for the evaluation of topical antimicrobial therapies. Hydrogels composed of gelatin type A and sodium alginate were integrated into a transwell system and crosslinked using microbial transglutaminase and calcium ions. This configuration enables passive diffusion of simulated wound fluid from the basolateral compartment, thereby mimicking key aspects of the wound environment. The model supports the growth of Pseudomonas aeruginosa biofilms within a three-dimensional matrix. The hydrogel system supported bacterial growth and microcolony formation during 48 h of incubation at 37 °C. The system was applied in both biofilm inhibition and eradication studies using tobramycin, ε-poly-L-Lysine and the commercially available wound gel Prontosan^®. Viable bacteria were quantitatively recovered through hydrogel dissolution followed by serial dilution and count of colony-forming units. Overall, the developed model provides a simple and accessible platform for quantitative evaluation of antibiofilm treatments. While not intended to fully replicate the complexity of native tissue, this system offers a practical alternative to collagen-based models and helps bridge the gap between conventional in vitro assays and more advanced wound models.