Lactic acid bacteria (LAB) from meat dry-salted Kaddid were evaluated using spoilage and safety criteria as a first step of multivariable selection. LAB were isolated, identified and characterized from Kaddid prepared under controlled conditions. After preliminary physiological characterization, isolates (n = 39) were subjected to (GTG)5-PCR analysis and 16S rRNA sequencing. Major LAB populations were, Lactiplantibacillus paraplantarum (41%), Latilactobacillus sakei/subsp. sakei (25%), Enterococcus faecium (13%), Pediococcus acidilactici (10%), Enterococcus hirae (6%) and Weissella cibaria (5%). Antagonistic activity against pathogens/contaminants and yeast/molds showed strains with antilisterial and antifungal activity. Bacteriocin-like inhibitory substances (BLIS) showed high titles (AU/mL) against Listeria (L.) monocytogenes FBUNT. The examination of bacteriocin genes revealed Lpb. paraplantarum K18, Lat. sakei K25 and Lat. sakei subsp. sakei K22, K26 strains harboring skgA and sakP structural genes encoding for sakacin G and P bacteriocins. Resistance/susceptibility of lactobacilli strains to antibiotics showed high phenotypic resistance to tetracycline (TET) while multi-resistance pattern was displayed by enterococci. Genotypic characterization exhibited only tetM out of 15 assayed genes, conferring resistance to TET. As a quality criterion, no exopolysaccharides and biogenic amines production were detected in the evaluated strains. Based on these results, Lpb. paraplantarum K18 strain, with inhibitory and antifungal activities, phenotypical susceptibility to the assayed antimicrobial compounds and low risk as spoilers, could be used as functional starter cultures for safe fermented meat production.

Background: The vaginal microbiota of healthy women is predominantly composed of lactic acid bacteria (LAB), particularly species from the lactobacilli group, which contribute to the maintenance of vaginal health through multiple protective mechanisms. Objectives: In the present study, vaginal LAB isolated from healthy premenopausal Algerian women were evaluated for their probiotic potential. Methods: A total of 259 LAB isolates were initially screened for antimicrobial activity against vaginal pathogens, among which 164 strains exhibited inhibitory effects. Based on antimicrobial capacity and biofilm formation ability, 38 strains were selected for further characterization. A refined subset of 15 strains belonging to Lactiplantibacillus (Lpb.) plantarum, Limosilactobacillus (Lmb.) fermentum, and Ligilactobacillus (Lgb.) salivarius were subsequently identified according to their superior antimicrobial and probiotic-related properties. The selected strains were evaluated for several functional and safety characteristics, including antimicrobial activity, production of lactic acid and hydrogen peroxide (H₂O₂), biofilm formation, auto-aggregation, cell surface hydrophobicity, antibiotic susceptibility, hemolytic activity, and tolerance to acidic conditions. These studies were complemented with comparative genomics using the complete genome sequences of selected strains. Results: The isolates demonstrated significant inhibitory activity against vaginal pathogens associated with aerobic vaginitis, and vulvovaginal candidiasis. In addition, strong correlations were observed between metabolite production and antimicrobial activity. Several strains also exhibited enhanced biofilm formation, aggregation capacity, and favorable safety profiles. Among the tested isolates, Lmb. fermentum 70BJ2, Lpb. plantarum 87JG8, and Lpb.plantarum N17 emerged as particularly promising probiotic candidates due to their combined antimicrobial, metabolic, and adhesion-related properties. Conclusions: Overall, these findings demonstrate that the vaginal microbiota of healthy Algerian women represents a valuable source of potential probiotic strains and provide a strong basis for future in vivo validation and clinical application in the prevention and management of vaginal infections.

Biosurfactants are environmentally friendly surface-active compounds with promising applications in environmental remediation. In this study, a biosurfactant-producing bacterium, Bacillus (B.) velezensis SHB.28, was isolated from heavy metal-contaminated soil and evaluated for its ability to produce biosurfactants using date syrup as a low-cost agro-industrial substrate. Screening assays including drop-collapse (DC), oil spreading (OS), and emulsification index after 24 h E₂₄ (%) confirmed strong biosurfactant production. Culture conditions were optimized, revealing that 30 °C, pH 6, and a C/N ratio between 10% and 20% provided optimal production. Under optimized conditions, the crude biosurfactant extract yield reached 2.16 g/L within 24 h, accompanied by a reduction in surface tension from 69 to 29.1 dyn/cm and high emulsification activity. Kinetic modeling showed that emulsification activity followed an exponential growth model (R² = 0.985), whereas surface tension dynamics were well described by a spike decay–plateau model (R² = 0.998). Structural characterization using Fourier-transform infrared spectroscopy (FTIR), electrospray ionization–mass spectrometry (ESI–MS), and nuclear magnetic resonance (NMR) spectroscopy revealed that the biosurfactants are surfactin- and iturin-like cyclic lipopeptides composed of a β-hydroxy fatty acid chain (C₁₃–C₁₅) linked to a cyclic peptide moiety. The biosurfactant exhibited a critical micelle concentration of 100 mg/L and an anionic character with a pHpzc of 5.7. Furthermore, it demonstrated high efficiency in removing heavy metals, achieving removal efficiencies of 99.88% for Fe²⁺, 99.69% for Pb²⁺, and 94.72% for Cu²⁺, outperforming conventional surfactants such as SDS and Tween 80. These findings highlight the potential of date syrup-derived surfactin and iturin from B. velezensis SHB.28 as sustainable and efficient biosurfactants for environmental remediation and heavy metal removal applications.