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The main objective of this study is to isolate and identify lactic acid bacteria (LAB) from various Egyptian dairy products, examine their antibacterial and hemolysis potential, and ensure their safety when used as starter cultures in different dairy industries. Egyptian dairy products are often made without the use of commercial starter cultures, using raw milk and artisanal methods. The most popular traditional dairy products are Laban Rayeb and Zabady, as well as the cheese varieties of Ras, Domiati, and Karish. The microbial communities used for fermentation and the diversity of lactic acid bacteria are the most important factors that can affect the quality of these products. In order to investigate the diversity of cocci lactic acid bacteria in Egyptian dairy products, 70 samples of raw or fermented milk and cheeses were collected from traditional cheese-making factories, local markets, and farmhouses located in the Delta area of Egypt. Following this, the LAB were isolated from the samples. One hundred fifty-seven isolates of Gram-positive, catalase-negative, and cocci bacterial species were identified via rep-PCR, and some isolates were confirmed using pheS and 16S rRNA gene sequencing, as follows: Streptococcus infantarius subsp. infantarius (three isolates), Enterococcus hirae (three isolates), Enterococcus faecium (ninety-six isolates), Enterococcus faecalis (forty isolates), Enterococcus durans (six isolates), Lactococcus garvieae (one isolate), Pediococcus acidilactici (seven isolates), and Lactococcus lactis subsp. Lactis (one isolate). These findings validate that five strains have strong antibacterial activity against Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes, and one hundred thirty-four strains were safe for hemolysis. The five strains were selected as protective cultures, including Pediococcus acidilactici, Lactococcus lactis subsp. lactis, E. faecalis, and E. faecium. [ABSTRACT FROM AUTHOR]

The antibiofilm, antibacterial, antioxidant, and anticancer activities of the methanolic extract of Padina pavonica L. were determined. Results deduced that the algal extract had a high biofilm formation inhibitory action done via crystal violet (CV) assay, to 88–99%. The results showed a strong antibacterial against the identified bacteria species. Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumonia, Bacillus subtilis, and the extract had moderate antibacterial activity against Escherichia coli, Pseudomonas fluorescens and Streptococcus agalactiae. The algal extract has a concentration-dependent DPPH radical scavenging activity (84.59%, with IC50 = 170.31 µg/ml). The inhibitory percent of P. pavonica methanolic extract in vitro antiproliferative activity was 1.79–98.25% with IC50 = 15.14 µg/ml against lung carcinoma. Phenols, terpenes, amino acids, alkaloids, flavones, alcohols, and fatty acids were among the metabolites whose biological actions were evaluated. In conclusion, for the first time, P. pavonica methanolic extract exhibited effective antibiofilm, antibacterial, antioxidant, and anticancer activities. [ABSTRACT FROM AUTHOR]

ULVA selenium nanoparticles (USeNPs) were synthesized and characterized, then examined for their wound healing capacity through in vitro assay showing promising healing (82.27%) with USeNPs concentration (500µg/mL). We also determined the antifungal potential via agar well diffusion technique, minimum inhibitory concentration (MIC), which was evaluated by a micro-dilution assay. The synergistic effect of the USeNPs individually or in combination with standard antifungal antibiotic (ketoconazole;100μg/mL) was studied against Cryptococcus neoformans RCMB 0049001 and Candida lipolytica RCMB 005007(1). Geotrichum candidum RCMB 041001 was also checked by agar well diffusion assay, followed by transmission electron microscopy to assess different changes in the most sensitive fungal yeast cells. The results indicated that USeNPs have a promising antifungal effect against C. neoformans RCMB 0049001 and C. lipolytica RCMB 005007(1) by achieving remarkable inhibition zones. In comparison, no effect was detected on G. candidum RCMB 041001. The MIC was found to be 78.1μg and 312.5μg for C. neoformans RCMB 0049001 and C. lipolytica RCMB 005007(1), respectively. The biosynthetic USeNPs have a strong antifungal potential and can elevate and strengthen the action of ketoconazole antibiotic towards different fungal pathogens, and this was obvious In the experiment of synergism carried out in the present study based on combining ketoconazole;100μg/mL with USeNPs, which resulted in a detached C. neoformas RCMB 0049001 cells with a severe dramatic change. [ABSTRACT FROM AUTHOR]

An attempt is made to use cheese whey water (Ww) and sweet potato extract (SPE) separately or in combination to manipulate a cheap and economical media component for large scale production of lactobacilli. Primarily, lactobacilli species were cultivated on de-Man Rogosa and Sharp medium (MRS) then, these strains were grown in (SPE) and (Ww) using a flask fermentation technique at 37°C, followed by applying a statistical experimental design (Plackett-Burman (PB)) via a statistical software MiniTab16 to optimize the media constituents for achieving a large scale production of lactobacilli; with studying the main effect of medium components referring to the most critical nutritional factors in the newly organized medium. Generally, our results indicated that both sweet potato and whey water extract (SPWE); could be used for the growth of lactobacilli instead of (MRS) medium. Further, other experiments were done to show how lactobacilli growth will be affected by pH and various types of whey; using standard plate count method. Highest counts for Lactobacillus acidophilus (2r) and Lactobacillus rhamnosus (190RZFAAU) were at pH 6 and pH 6.5 in (SPWE) medium. Depending on the above investigations; (SPWE) medium including the addition of different types; whey water can be used as an alternative growth medium for lactobacilli instead of MRS which was traditionally used for growing these kinds of Lactic acid bacteria (LAB). Additionally, findings in this study can help in cleaning our environment from the huge disposal quantities of whey resulted as byproduct from cheese industries. [ABSTRACT FROM AUTHOR]

Various antibiotics are available, including gentamicin, chloramphenicol, ampicillin, amoxicillin, and streptomycin, but they have some restrictions. Many microorganisms are resistant to these medications. A new antimicrobial source must be found or developed to solve this issue. Inhere, extract from seaweeds Ulva lactuca was investigated for its antibacterial activity using a well diffusion assay against Klebsiella pneumoniae, and a promising inhibition zone diameter was recorded to be 14.04 mm. The biochemical structure of the antibacterial compound was determined via GC-MS and FTIR analysis. Also, a micro-dilution assay was used to calculate the minimum concentration that makes inhibition (MIC) to be 1.25 mg/ml from U. extract reliable to prevent the visibility of any bacterial growth, this was followed by examining the antibacterial effect of U. Lactuca methanolic extract alone and the synergetic effect of U. Lactuca methanolic extract in combination with two different antibiotics (gentamicin and chloramphenicol). This was assayed by the agar well diffusion method to achieve promising and strong inhibiting power against K. pneumoniae. It was deduced that the maximum synergism could be achieved by adding 2.5 mg/ml of Ulva methanolic extract to gentamicin (4 µg/ml), and the results were illustrated obviously via transmission electron microscope in which severe morphological deteriorations were experienced by the treated cells. From this study, we can conclude that U. lactucae extract has the power to aid antibiotics in reducing the growth of pathogenic K. pneumoniae., (© 2023. The Author(s).)