TL;DR
This is the first study to demonstrate that IBA and OA exert significant antibiofilm and anti-motility effects against P. aeruginosa NG4 at low concentrations under the conditions tested, providing a foundation for future mechanistic and biological investigations.
MUR exhibits high efficacy against both planktonic and biofilm-forming MDR P. aeruginosa, and its synergy with colistin and tobramycin highlights its potential as a strategic combination partner.
It is suggested that biogenically synthesized MgO NPs hold considerable promise as antibacterial and antibiofilm agents against MDR Gram-negative pathogens.
Abstract This study evaluated the antimicrobial and antibiofilm activities of metabolites produced by a Streptomyces strain isolated from impacted soil against Staphylococcus aureus. The study employed the Streptomyces sp. SLA3 strain. Secondary metabolites were obtained through submerged fermentation followed by liquid-liquid extraction. Chemical characterization was performed using gas chromatography coupled with mass spectrometry (GC-MS). The pathogenic models included S. aureus ATCC 25923 and five clinical isolates. Antimicrobial activity was assessed by the agar diffusion method and determination of minimum inhibitory concentration (MIC). Antibiofilm activity was evaluated through inhibition of biofilm formation and eradication of preformed biofilms. Toxicity evaluation was conducted using Tenebrio molitor larvae and hemolytic activity assays. Chemical characterization of the extract revealed a predominance of 2,4-bis(1,1-dimethylethyl)phenol and long-chain saturated fatty acids (myristic, palmitic, and stearic acids). Inhibition halos reached approximately 35 mm, and MIC values ranged from 1,000 to 2,000 μg/mL. The S. aureus CIBC 9722 strain exhibited significant inhibition of biofilm formation (p < 0.05). For S. aureus ATCC 25923, S. aureus CIBC 9722, S. aureus CIBC 20, and S. aureus CIBC 14, all extract concentrations promoted a significant reduction in preformed biofilms (p < 0.05). In the toxicity assay using T. molitor larvae, groups treated with extract concentrations of 1,000-500 µg/mL exhibited a survival rate of 75%. The effective concentration required to induce 50% hemolysis (HC50) was estimated at 329.9 µg/mL. These findings highlight the biotechnological potential of metabolites from Streptomyces sp.
Findings indicate that N. sativa seed extracts possess antibiofilm potential against P. aeruginosa at subinhibitory concentrations, however, as this was a purely phenotypic study, the mechanisms underlying the observed inhibition remain speculative and require direct experimental investigation.
Candida albicans biofilms are a major cause of persistent infections and contribute to antifungal resistance as well as limitations in drug delivery. Targeting virulence traits such as biofilm formation and hyphal transition represents an effective strategy for controlling fungal pathogenicity without exerting strong selective pressure on planktonic growth. In this study, a library of structurally diverse benzophenone derivatives was screened to identify compounds with antibiofilm and anti-hyphal activities against azole-resistant C. albicans. Most benzophenone derivatives exhibited weak antifungal activity (MIC ≥ 200 µg/mL). However, several halogenated benzophenones markedly suppressed biofilm formation. Among them, decafluorobenzophenone at 10 µg/mL displayed the strongest inhibition, reducing biofilm formation to approximately 1–2% of control levels while maintaining substantial planktonic cell viability. Microscopy confirmed hyphal suppression, while qRT-PCR showed a 36-fold reduction in ALS3 expression. These findings indicate that multi-halogenated benzophenones act primarily as anti-virulence agents targeting biofilm formation and hyphal development. Molecular docking suggested a possible interaction of decafluorobenzophenone with the Als3 binding pocket. Decafluorobenzophenone showed low toxicity, with unaffected Caenorhabditis elegans viability at 10 µg/mL, plant germination at 100 µg/mL, and only slight hemolysis at 100 µg/mL. The results highlight halogen substitution as a key structural determinant and identify benzophenone scaffolds as promising leads for developing novel antibiofilm strategies against azole-resistant Candida infections.
