Microbial levan has great potential as a functional biopolymer in different fields including foods, feeds, cosmetics, and the pharmaceutical and chemical industries. In this study, a good levan producer bacterial strain of Pseudomonas fluorescens strain ES, isolated from soil in Egypt in a previous study, was used. Levan production by this strain was optimized using Plackett-Burman experimental design (PBD) to screen the critical factors of several process variables and Centered Central Composite Design (CCD) was applied for further estimation of the relationship between the variables and the response as well as optimization of the levels. Plackett-Burman (P-B) design showed a p-value 0.0144 less than 0.05 indicated the significance of the model. Sucrose, potassium dihydrogen phosphate, yeast extract and pH value showed the most significant effect on levan concentration at the values of 89.17, 65.83, 24.17, and 15.83, respectively. The purified levan polymer was characterized using different Physico-chemical methods such as Fourier Transform Infrared Spectrometer (FTIR), Nuclear magnetic resonance (NMR), and High-Performance Liquid Chromatography (HPLC) to determine the main composition and functional groups in the obtained polymer. HPLC results indicated that the polymer purification increased the percentage of fructose residue from 75 up to 89. Furthermore, 1 H and 13 C NMR spectroscopy analysis showed great matching between the obtained signal for our polymer with that reported in other people ’ s work. The obtained levan polymer exhibited cytotoxic activity against Human epidermoid Skin carcinoma and Hepatocellular carcinoma with IC50 of 469 and 222.7 µg/ml, respectively. Antioxidant activity was determined using DPPH assay and the percentage of inhibition at 1000 µg/ml was found to be <50 (13.89 ± 1.07) with IC50 of (24.42 ± 0.87).

The biopolymer levan has sparked a lot of interest in commercial production and various industrial applications. In this study, a bacterial isolate with promising levan-producing ability was isolated from a soil sample obtained from Princess Nourah bint Abdulrahman University in Saudi Arabia. The isolate has been identified and submitted to GenBank as Bacillus subtilis MZ292983.1. The bacterial levan polymer was extracted using ethyl alcohol (75%) and CaCl2 (1%) and then characterized using several approaches, such as Fourier transform infrared spectrometry and nuclear magnetic resonance. The IR spectrum of the levan polymer showed characteristic peaks confirming characteristics of polysaccharides, including a broad stretching peak of OH around 3417 cm−1 and aliphatic CH stretching was observed as two peaks at 2943, and 2885 cm−1. In addition, the FTIR spectrum featured an absorption at 2121 cm−1, indicating the fingerprint of the β-glycosidic bond. Based on 1H and 13C NMR spectroscopy analysis, six unexchanged proton signals related to fructose as a forming monomer of levan were observed. Evaluation of levan’s antibacterial effect against two pathogenic bacteria, S. aureus (ATCC 33592) and E. coli (ATCC 25922), showed inhibition zones of 1 cm and 0.8 cm in diameter, respectively, with MICs of more than 256 μg mL−1 for both strains. Moreover, the antibiofilm property of the levan polymer was assessed and the results showed that the inhibition rate was positively proportional to the levan concentration, as the inhibition percentages were 50%, 29.4%, 29.4%, 26.5%, and 14.7% at concentrations of 2, 1, 0.5, 0.25, and 0.125 mg mL−1, respectively. Levan showed a significant role in burn healing properties since it accelerated the process of healing burn-induced areas in rats when compared with those either treated with normal saline or treated with the cream base only.

Major health issues, such as the rise in oxidative stress, incidences of Alzheimer’s disease, and infections caused by antibiotic-resistant microbes, have prompted researchers to look for new therapeutics. Microbial extracts are still a good source of novel compounds for biotechnological use. The objective of the current work was to investigate marine fungal bioactive compounds with potential antibacterial, antioxidant, and acetylcholinesterase inhibitory effects. Penicillium chrysogenum strain MZ945518 was isolated from the Mediterranean Sea in Egypt. The fungus was halotolerant with a salt tolerance index of 1.3. The mycelial extract showed antifungal properties against Fusarium solani with an inhibitory percentage of 77.5 ± 0.3, followed by Rhizoctonia solani and Fusarium oxysporum with percentages of 52 ± 0.0 and 40 ± 0.5, respectively. The extract also showed antibacterial activity against both Gram-negative and Gram-positive bacterial strains using the agar diffusion technique. The fungal extract was significantly more effective with Proteus mirabilis ATCC 29906 and Micrococcus luteus ATCC 9341; inhibition zones recorded 20 and 12 mm, respectively, compared with the antibiotic gentamycin, which recorded 12 and 10 mm, respectively. The antioxidant activity of the fungus extract revealed that it successfully scavenged DPPH free radicals and recorded an IC50 of 542.5 µg/mL. Additionally, it was capable of reducing Fe3+ to Fe2+ and exhibiting chelating ability in the metal ion-chelating test. The fungal extract was identified as a crucial inhibitor of acetylcholinesterase with an inhibition percentage of 63% and an IC50 value of 60.87 µg/mL. Using gas chromatography–mass spectrometry (GC/MS), 20 metabolites were detected. The most prevalent ones were (Z)-18-octadec-9-enolide and 1,2-Benzenedicarboxylic acid, with ratios of 36.28 and 26.73%, respectively. An in silico study using molecular docking demonstrated interactions between the major metabolites and the target proteins, including: DNA Gyrase, glutathione S-transferase, and Acetylcholinesterase, confirming the extract’s antimicrobial and antioxidant activity. Penicillium chrysogenum MZ945518, a halotolerant strain, has promising bioactive compounds with antibacterial, antioxidant, and acetylcholinesterase inhibitory activities

Public key encryption with key word search (PEKS) enables user Alice to send a secret key to a server that will enable the server to locate all encrypted messages containing the keyword, but learn nothing else. In this paper, we propose a new scheme the Efficient Public Key Encryption with Keyword Search (EPEKS). Firstly we explained the construction of new scheme (EPEKS). (EPEKS) doesn't base on Identity Based Encryption or pairing which was used in the construction of the (PEKS) that proposed in Boneh's paper and other papers; it is based on Public Key Cryptosystem. Secondly, we proposed provably secure (EPEKS) scheme that refreshes keywords and processes multiple keywords. Finally, we described the security of the new scheme by using Cryptographic algorithm and Hash function.

T HE LEVEL of bacterial contamination in two essential oil-treated or untreated minced meat samples collected from different butcher shops in Cairo Governorate in July 2019 (sample I) and January 2020 (sample II) was evaluated in this study. The samples were subjected to sensory, bacteriological, and chemical analysis. The counts of anaerobic, aerobic, coliform bacteria, Escherichia coli, and Staphylococcus aureus were increased in the untreated portions of both samples. Generally, the total bacterial contamination in sample I, which was collected in the summer, was greater than that in sample II, which was collected in winter. Adding 2% marjoram or thyme essential oils to the minced meat samples significantly increased their shelf life at 2ºC up to 7 and 8 days, compared with the untreated portions of the two samples, whose shelf life was 4 and 5 days, respectively. These results indicate that treatment of minced meat with essential oils, especially marjoram or thyme, extends its shelf life at 2ºC by reducing the bacterial contamination without affecting the quality and sensory properties of the meat. This study was carried out to compare the different bacterial counts in minced meat at two different seasons of the year (summer and winter), with the goal of extending the shelf life by reducing bacterial counts using different essential oils.

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