Abdelkhaleq Elmoslih

Bifurcaria bifurcata R. Ross 1958 is a perennial brown seaweed belonging to the Sargassaceae family and represents an underexploited marine bioresource with promising applications in the sustainable food and pharmaceutical sectors. To support its sustainable valorization as an alternative to synthetic additives, this study provides a comprehensive evaluation of the chemical composition, bioactivity, and mineral profile of B. bifurcata to support its valorization. The essential oil, obtained by hydrodistillation and characterized by GC—MS, revealed a rich chemical profile comprising 51 compounds, of which 42 were identified, accounting for 95.37% of the total composition. The major constituents included 2′-hydroxy-4′,5′-dimethylacetophenone (13.11%), benzene, 1-ethyl-3,5-dimethyl- (9.79%), 1,5,9-cyclododecatriene, 1,5,9-trimethyl- (8.57%), and benzene, 1-(1,1-dimethylethyl)-4-methoxy- (8.52%). The essential oil exhibited moderate antioxidant activity under in vitro conditions, with a total antioxidant activity of 74.85 ± 2.78 mg E α-tocopherol/g and IC₅₀ values of 0.103 ± 0.004 (DPPH), 0.106 ± 0.002 (FRAP), and 2.672 ± 0.123 mg/mL (β-carotene bleaching assay). In addition, notable antibacterial activity was observed against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Listeria monocytogenes, with inhibition zones ranging from 10 to 12 mm. Mineral analysis of the seaweed powder highlighted its nutritional importance, with high levels of organic matter, proteins, and sugars, along with substantial concentrations of essential macroelements (K, Ca, Mg, and Na) and trace elements (Fe, Mn, and Zn). Overall, these findings demonstrate the potential of B. bifurcata as a sustainable marine resource for the development of natural antioxidants, antimicrobial agents, and mineral-rich ingredients, contributing to environmentally friendly food systems and green pharmaceutical applications.

Lactic acid bacteria (LAB) are increasingly recognized for their role in food biopreservation due to their ability to synthesize antimicrobial compounds. Milk naturally harbors a wide variety of LAB, offering a promising source for identifying strains with biopreservative potential. This study investigated the antagonistic effects, safety characteristics, and technological properties of LAB strains isolated from traditionally fermented milk. Thirty-two dairy samples were analyzed, and the resulting LAB isolates were screened for inhibitory activity against Listeria monocytogenes CECT 4032 and Staphylococcus aureus CECT 976 using agar spot and well diffusion assays. All tested strains exhibited strong antimicrobial effects, with particularly notable inhibition of L. monocytogenes. After phenotypic screening, five representative isolates were selected for molecular identification and further assessment of safety-related attributes, functional capabilities, auto- and co-aggregation properties. 16S rRNA gene sequencing revealed that four strains belonged to the genus Enterococcus, specifically, one E. faecium and three E. durans, while one was classified as a Lactococcus species. Moreover, none of the strains showed proteolytic or lipolytic activities which highlights their potential use in dairy fermentation processes.

Lactic acid bacteria (LAB) are increasingly recognized for their role in food biopreservation due to their ability to synthesize antimicrobial compounds. Milk naturally harbors a wide variety of lactic acid bacteria, offering a promising source for identifying strains with biopreservative potential. This study investigated the antagonistic effects, safety characteristics, and technological properties of LAB strains isolated from traditionally fermented milk. Thirty-two dairy samples were analyzed, and the resulting LAB isolates were screened for inhibitory activity against Listeria monocytogenes CECT 4032 and Staphylococcus aureus CECT 976 using agar spot and well diffusion assays. All tested strains exhibited strong antimicrobial effects, with particularly notable inhibition of L. monocytogenes. After phenotypic screening, five representative isolates were selected for molecular identification and further assessment of safety-related attributes, functional capabilities, auto- and co-aggregation properties 16S rRNA gene sequencing revealed that four strains belonged to the genus Enterococcus, specifically, one E. faecium and three E. durans, while one was classified as a Lactococcus species. Moreover, none of the strains showed proteolytic or lipolytic activities which highlights their potential use in dairy fermentation processes.

Diffusion methods, including agar disk-diffusion and agar well-diffusion, as well as dilution methods such as broth and agar dilution, are frequently employed to evaluate the antimicrobial capacity of extracts and essential oils (EOs) derived from Origanum L., Syzygium aromaticum, and Citrus L. The results are reported as inhibition diameters (IDs) and minimum inhibitory concentrations (MICs), respectively. In order to investigate potential sources of variability in antimicrobial susceptibility testing results and to assess whether a correlation exists between ID and MIC measurements, meta-analytical regression models were built using in vitro data obtained through a systematic literature search. The pooled ID models revealed varied bacterial susceptibilities to the extracts and in some cases, the plant species and methodology utilised impacted the measurements obtained (p < 0.05). Lemon and orange extracts were found to be most effective against E. coli (24.4 ± 1.21 and 16.5 ± 0.84 mm, respectively), while oregano extracts exhibited the highest level of effectiveness against B. cereus (22.3 ± 1.73 mm). Clove extracts were observed to be most effective against B. cereus and demonstrated the general trend that the well-diffusion method tends to produce higher ID (20.5 ± 1.36 mm) than the disk-diffusion method (16.3 ± 1.40 mm). Although the plant species had an impact on MIC, there is no evidence to suggest that the methodology employed had an effect on MIC (p > 0.05). The ID–MIC model revealed an inverse correlation (R² = 47.7%) and highlighted the fact that the extract dose highly modulated the relationship (p < 0.0001). The findings of this study encourage the use of extracts and EOs derived from Origanum, Syzygium aromaticum, and Citrus to prevent bacterial growth. Additionally, this study underscores several variables that can impact ID and MIC measurements and expose the correlation between the two types of results.