Evaluation of antibacterial and antibiofilm activity of Lacticaseibacillus sp. KJK14S1 strain isolated from unexplored region of Indian Sundarbans against Gram-negative bacteria

Antibacterial and Antibiofilm Activity of Ethanolic and Methanolic Nigella sativa L. Seed Extracts Against Pseudomonas aeruginosa ATCC 27853

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.

Antimicrobial and antibiofilm potential of Streptomyces sp. metabolites against Staphylococcus aureus

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.

Biofilm Formation and Para-cresol Production by Clostridioides difficile Under the Influence of Phytonutrients from Rhus chinensis

Antimicrobial, antibiofilm, and virulence gene modulatory effects of supercritical CO₂ extracts of Thymbra spicata against clinical MRSA isolates.

Genomic characterization and biological activities of cell-free supernatant from Lactiplantibacillus pentosus CROT01 against clarithromycin-resistant Helicobacter pylori

Helicobacter pylori is a major gastric pathogen associated with chronic gastritis, peptic ulcers, and gastric cancer, while increasing antibiotic resistance has reduced the effectiveness of standard eradication therapies. This study investigated the antibacterial, antibiofilm, anti-inflammatory, probiotic-related, and genomic properties of cell-free supernatant (LCFS) derived from Lactiplantibacillus pentosus CROT01 against H. pylori. LCFS exhibited inhibitory activity against all tested H. pylori strains, including the clarithromycin-resistant strain ATCC 700684, with inhibition zones ranging from 10.67 ± 0.58 to 17.33 ± 1.53 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) ranged from 12.5–50 mg/mL and 25–50 mg/mL, respectively. LCFS significantly inhibited biofilm formation and eradicated established H. pylori biofilms. Scanning electron microscopy revealed marked morphological alterations in treated cells, including membrane disruption, deformation, and cellular shrinkage. Anti-inflammatory activity was demonstrated through suppression of nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 cells. In addition, L. pentosus CROT01 exhibited tolerance to acidic pH and pancreatin, high cell surface hydrophobicity, and moderate adhesion ability toward Caco-2 cells. Whole-genome sequencing identified several bacteriocin-associated genes, including plantaricin E, plantaricin F, pediocin, enterolysin A, and bovicin-related peptides, whereas no virulence-associated or acquired antimicrobial resistance genes were detected. Thus, these findings suggest that LCFS derived from L. pentosus CROT01 possesses promising anti-H. pylori activity and may represent a potential postbiotic-based strategy against antibiotic-resistant H. pylori infection.

Antimicrobial properties of postbiotics of different LAB against multidrug resistance bacteria

It was shown the comparative antimicrobial activity of postbiotics isolated from lactic acid bacteria (LAB) strains of genus Enterococcus and Lactobacillus against three broad panelsof human pathogens showed strain-specific inhibitory effects, highlighting their narrower antimicrobial spectrum relative to antibiotics.