Lactic acid bacteria (LAB) are of major concern due to their health benefits. Fermented food products comprise variable LAB demonstrating probiotic properties. Discovering and evaluating new probiotics in fermented food products poses a global economic and health importance. Therefore, the present work aimed to investigate and evaluate the probiotic potentials of LAB strains isolated from Egyptian fermented food. In this study, we isolated and functionally characterized 100 bacterial strains isolated from different Egyptian fermented food sources as probiotics. Only four LAB strains amongst the isolated LAB showed probiotic attributes and are considered to be safe for their implementation as feed or dietary supplements. Additionally, they were shown to exert antimicrobial activities against pathogenic bacteria and anticancer effects against the colon cancer cell line Caco-2. The Enterococcus massiliensis IS06 strain was exclusively reported in this study as a probiotic strain with high antimicrobial, antioxidant, and anti-colon cancer activity. Hitherto, few studies have focused on elucidating the impact of probiotic supplementation in vivo. Therefore, in the current study, the safety of the four strains was tested in vivo through the supplementation of rats with potential probiotic strains for 21 days. The results revealed that probiotic bacterial supplementation in rats did not adversely affect the general health of rats. The Lactiplantibacillus plantarum IS07 strain significantly increased the growth performance of rats. Furthermore, the four strains exhibited increased levels of antioxidants such as superoxide dismutase and glutathione in vivo. Consistently, all strains also showed high antioxidant activity of the superoxide dismutase enzyme in vitro. Overall, these findings demonstrated that these isolated potential probiotics harbor desirable characteristics and can be applied widely as feed additives for animals or as dietary supplements for humans to exert their health benefits and combat serious diseases.

Antimicrobial resistance represents a significant global issue that requires the investigation of innovative approaches for infection management. In pursuit of alternative natural antimicrobials, nine plant essential oils were evaluated for their antibacterial properties against nine common bacterial pathogens. Among the tested essential oils, thyme essential oil demonstrated the highest antibacterial activity against all tested bacterial species, Thyme essential oil exhibited inhibition zones ranging from 17.3 to 51 mm with relative minimum inhibitory concentrations ranging from 99.2 to 450 µg/ml, implying the bactericidal effect. The ultrastructural changes in bacterial cells treated with thyme essential oil were visualized using transmission electron microscope. Thyme essential oil exhibited a potent inhibitory effect toward the biofilm formations for all the tested pathogenic strains. GC/MS analysis was used to determine the thyme essential oil composition. The major components of thyme essential oil were thymol (28.29%), o-cymene (18.31%), ç-terpinene (8.51%), eucalyptol (5%), linalool (2.86%), borneol (2.17%), á-myrcene (1.55%), à-pinene (1.52%) and camphene (1%). Molecular docking analysis demonstrated that the constituents present in the thyme essential oil had high binding affinity for ECF, FimH, LasR, PrfA and RhlA proteins, which were found to be associated with improved anti-biofilm efficacy. Furthermore, treatment with thyme essential oil led to the downregulation of essential genes associated with virulence and biofilm formation in the tested pathogens. These findings suggest that thyme essential oil has promising potential as an antibacterial and a biofilm inhibitory agent to combat bacterial infections in food and pharmaceutical industries.

Background: Vitamin B₁₂ is a crucial B-group vitamin, first isolated from the liver due to its role in combating pernicious anemia. It is distinguished by its unique and complex structure, which makes its chemical synthesis challenging and expensive. Consequently, vitamin B₁₂ is alternatively obtained through microbial fermentations. Molasses, an affordable and safe agro-industrial waste, can be used as a carbon source for vitamin B₁₂ production, offering a cost-effective alternative to expensive sugars in the production medium. Results: A total of 87 yeast, actinomycete, and bacterial isolates were screened for vitamin B₁₂ production, with 15 isolates showing high productivity. Bacillus isolates were selected for further analysis using MALDI-TOF and molecular identification. These isolates were identified as four strains of Bacillus subtilis (MZ08, JT10, BY11, and JT17), one strains of Bacillus sp. (CB09), and one strain of Peribacillus acanthi (MZ01). Genetic circuits associated with vitamin B₁₂ production were demonstrated in a closely related strain of Peribacillus acanthi MZ01 strain. Three strains (MZ01, MZ08, and JT17) were selected for further evaluation of vitamin B₁₂ productivity under different sugar types (glucose, sucrose, fructose, lactose, and galactose) and varying inoculum sizes. The inoculum size significantly impacted vitamin B₁₂ production, with an increase from 5 to 10% enhancing yields. The ability of the strains to produce vitamin B₁₂ varied depending on the type of sugar used. Peribacillus acanthi MZ01 strain showed the highest productivity and subsequently, selected for optimizing vitamin B₁₂ production conditions using response surface methodology. Furthermore, the optimized conditions were then applied to molasses-based medium to achieve high vitamin B₁₂ yields by MZ01 strain. Conclusion: In this study, Peribacillus acanthi was characterized for the first time as a vitamin B₁₂ producer, demonstrating high productivity among various tested strains. The optimization of production conditions using response surface methodology, further enhanced vitamin B₁₂ yields, showcasing the strain’s efficiency in microbial fermentations. This research also highlights the potential of using molasses as a cost-effective alternative carbon source, significantly reducing production costs.

Honey has long been recognized for its antimicrobial properties, attributed to components such as polyphenols and biodefense proteins. Among honey types, Manuka honey, rich in methylglyoxal, and citrus honey, abundant in flavonoids and bioactive enzymes, exhibit potent antimicrobial activity. This study aims to enhance the antimicrobial and antibiofilm efficacy of Manuka and citrus honey by incorporating natural additives—aloe vera, Indian costus, and mint essential oil—into cream formulations. Two emulsion types, aerosil fumed silica-based and arabic gum-based, were prepared and optimized using sonication. The antimicrobial activity of these formulations was assessed against pathogenic bacteria, including Bacillus cereus, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar Typhimurium, Methicillin-resistant Staphylococcus aureus, Listeria monocytogenes, Micrococcus luteus, Escherichia coli O157:H7, and Klebsiella pneumoniae, as well as fungi such as Candida albicans and Aspergillus niger. The most effective formulations demonstrated inhibition zones of up to 28 mm against B. cereus and 24 mm against S. Typhimurium. Additionally, antibiofilm activity was evaluated using a 3D biofilm model, with formulations containing citrus honey and Indian costus or Manuka honey and aloe vera achieving biofilm reductions of 44.39% and 21.33%, respectively, against P. aeruginosa and MRSA. Furthermore, the composition of the citrus honey was analyzed using gas chromatography-mass spectrometry to identify the volatile and non-volatile compounds contributing to their antimicrobial properties. These findings suggest that honey-based formulations enhanced with natural additives hold significant potential for combating biofilm-associated infections.

Exploration of new niches for microorganisms capable of degrading recalcitrant molecules is still required. We hypothesized that the gut microbiota associated with the field S. frugiperda population carries pesticide-degrading bacteria that would enhance the host’s ability to metabolize pesticides. Three strategies were implemented to address this principle: (i) isolation and identification of chlorpyrifos-degrading gut bacteria from field-collected S. frugiperda larvae; (ii) evaluation of chlorpyrifos biodegradation capacity through in vitro assays; and (iii) assessment of the impact of specific bacterial taxa capable of degrading chlorpyrifos directly within the gut. In this study, we successfully isolated four chlorpyrifos-degrading gut bacterial isolates from a field-collected population of S. frugiperda. These isolates were identified using 16S rDNA sequencing as Klebsiella quasipneumoniae strain 60D (PP504878), Klebsiella pneumoniae strain 64D (PP504879), Klebsiella pneumoniae strain 66D (PP504880), and Klebsiella pneumoniae strain 71D (PP504881). In vitro chlorpyrifos degradation assays revealed that all isolates exhibited strong degradative capacities, with Klebsiella pneumoniae strain 64D achieving the highest degradation rate, 80.38%, after one day of inoculation. In contrast, in vivo chlorpyrifos biodegradation assessment demonstrated a clear protective effect of gut bacteria on host survival. Among the mono-associated groups, larvae colonized with Klebsiella pneumoniae strain 66D exhibited the most pronounced reduction in mortality by 19.16-fold compared to antibiotic-treated larvae following exposure to chlorpyrifos suspension.