Samy Selim

Antimicrobial activity of essential oils against vancomycin-resistant enterococci (vre) and Escherichia coli o157:h7 in feta soft cheese and minced beef meat.

Eleven essential oils (EOs) were evaluated for their antibacterial properties, against Vancomycin-Resistant Enterococci (VRE) and E. coli O157:H7. EOs were introduced into Brain Heart Infusion agar (BHI) (15ml) at a concentration of 0.25 to 2% (vol/vol) to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each pathogen evaluated. Results showed that the most active essential oils against bacteria tested were thyme oil, with MIC90 and MBC90 for the VRA strains of 0.25% and 0.5%, respectively. Eucalyptus, juniper and clove oils were the least potent agent, with MIC90 and MBC90 of 2%. Furthermore, the inhibitory effect of these EO were evaluated against VRE and E. coli O157:H7, experimentally inoculated (10 3 cfu/g) in Feta soft cheese and minced beef meat, which was mixed with different concentrations (0.1%, 0.5% and 1%) of the EO and stored at 7 °C for 14 days. Out of eucalyptus, juniper, mint, rosemary, sage, clove and thyme oils tested against target bacteria sage and thyme showed the best results. Clove and mint did not show any effect on VRE and E. coli O157:H7 in both kinds of studied foods. The addition of thyme oil at concentrations of 0.5 and 1% caused best significant reduction in the growth rate of VRE and E. coli O157:H7 in cheese and meat at 7 o C. It is concluded that selected plant EOs can act as potent inhibitors of both microorganisms in a food product. The results revealed the potential of thyme oil as a natural preservative in feta soft cheese and minced beef meat against VRE and E. coli O157:H7 contamination.

Metabolic analysis of various date palm fruit (Phoenix dactylifera L.) cultivars from Saudi Arabia to assess their nutritional quality

Date palm is an important crop, especially in the hot-arid regions of the world. Date palm fruits have high nutritional and therapeutic value and possess significant antibacterial and antifungal properties. In this study, we performed bioactivity analyses and metabolic profiling of date fruits of 12 cultivars from Saudi Arabia to assess their nutritional value. Our results showed that the date extracts from different cultivars have different free radical scavenging and anti-lipid peroxidation activities. Moreover, the cultivars showed significant differences in their chemical composition, e.g., the phenolic content (10.4–22.1 mg/100 g DW), amino acids (37–108 μmol·g−1 FW) and minerals (237–969 mg/100 g DW). Principal component analysis (PCA) showed a clear separation of the cultivars into four different groups. The first group consisted of the Sokary, Nabtit Ali cultivars, the second group of Khlas Al Kharj, Khla Al Qassim, Mabroom, Khlas Al Ahsa, the third group of Khals Elshiokh, Nabot Saif, Khodry, and the fourth group consisted of Ajwa Al Madinah, Saffawy, Rashodia, cultivars. Hierarchical cluster analysis (HCA) revealed clustering of date cultivars into two groups. The first cluster consisted of the Sokary, Rashodia and Nabtit Ali cultivars, and the second cluster contained all the other tested cultivars. These results indicate that date fruits have high nutritive value, and different cultivars have different chemical composition.

Viral and bacterial infections associated with camel (Camelus dromedarius) calf diarrhea in North Province, Saudi Arabia

Abstract Diarrhea and deaths in new-born camel calves were noticed by veterinary investigators and pastoralist in Saudi Arabia to be very high. Hence, it is thought to be necessary to investigate this problem from the virological and bacteriological point of view. The role of pathogenic bacteria and viruses in six different towns of North Province (Al-Assafia, Arar, Domat Aljandal, Hail, Skaka and Khoa) in Saudi Arabia was studied. Survey was conducted in diarrheic camel calves aged 12months or younger. In our study calf diarrhea was reported in 184 out of 2308 camels examined clinically during one year, the prevalence of diarrhea was found to be 8.0% in calves ranging from one month to one year. In the present study group A rotavirus and Brucella abortus were detected in 14.7% and 8.98%, respectively, using ELISA technique. Escherichia coli was isolated from diarrheic calf camel (58.2%) 99/170 samples during dry and wet season. Salmonella spp. and Enterococcus spp. were detected in 12% and 8.8% of the specimens, respectively. In this study enterotoxogenic E. coli (ET E. coli) was isolated from 7% of diarrheic camel, which indicates the strong correlation between the camel calf diarrhea and the detection of enterotoxogenic E. coli. This study represented the first report for the detection of group A rotavirus and B. abortus antigen and antibodies in calf camels in Saudi Arabia. It is recommended that the disease should be controlled by vaccination in calf camels.

Thermostable alkaline halophilic-protease production by Natronolimnobius innermongolicus WN18

This study reports the production and biochemical characterisation of a thermostable alkaline halophilic protease from Natronolimnobius innermongolicus WN18 (HQ658997), isolated from soda Lake of Wadi An-Natrun, Egypt. The enzyme was concentrated by spinning through a centriplus, centrifugal ultrafiltration Millipore membrane with a total yield of 25%. The relative molecular mass of this protease determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis ranged from 67 to 43 kDa. The extracellular protease of N. innermongolicus WN18 was dependent on high salt concentrations for activity and stability, and it had an optimum temperature of 60°C in the presence of 2.5 M NaCl. This enzyme was stable in a broad pH range (6–12) with an optimum pH of 9–10 for azocasein hydrolysis. This extracellular protease, therefore, could be defined as thermostable and haloalkaliphilic with distinct properties that make the enzyme applicable for different industrial purposes.

Susceptibility of imipenem-resistant Pseudomonas aeruginosa to flavonoid glycosides of date palm (Phoenix dactylifera L.) tamar growing in Al Madinah, Saudi Arabia

The fruits of the date palm ( Phoenix dactylifera L.) are consumed throughout the world and are an important part of the diet in the Middle East. Dates at tamar stage contain a wide array of flavones, but little is known about the antimicrobial of flavonoid glycosides compounds in dates. In this study, we evaluated the antimicrobial of flavonoid glycosides extracted from the date fruits grown in Al Madinah, Saudi Arabia at full ripe stage against imipenem-resistant P. aeruginosa (IRP). A chloroform fraction prepared from the date showed potent inhibitory activity against IRP. The active compounds were elucidated to be quercetin, luteolin, and apigenin based on their spectral analysis. Flavonoid glycosides showed significant antibacterial activities against IRP. These compounds represent novel leads, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents. Key words: Phoenix dactylifer, flavonoid glycosides, imipenem-resistant P. aeruginosa.

Zinc-induced differential oxidative stress and antioxidant responses in Chlorella sorokiniana and Scenedesmus acuminatus

Algae are frequently exposed to toxic metals, and zinc (Zn) is one of the major toxicants present. We exposed two green microalgae, Chlorella sorokiniana and Scenedesmus acuminatus, to sub-lethal concentrations (1.0 and 0.6mM) of Zn for seven days. Algal responses were analysed at the level of growth, oxidative stress, and antioxidants. Growth parameters such as cell culture yield and pigment content were less affected by Zn in C. sorokiniana, despite the fact that this alga accumulated more zinc than S. acuminatus. Also, C. sorokiniana, but not S. acuminatus, was able to acclimatize during long-term exposure to toxic concentrations of the test metals (specific growth rate (µ) was 0.041/day and total chlorophyll was 14.6mg/mL). Although, Zn induced oxidative stress in both species, C. sorokiniana experienced less stress than S. acuminatus. This could be explained by a higher accumulation of antioxidants in C. sorokiniana, where flavonoids, polyphenols, tocopherols, glutathione (GSH) and ascorbate (ASC) content increased. Moreover, antioxidant enzymes glutathione S transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX), showed increased activities in C. sorokiniana. In addition to, and probably also underlying, the higher Zn tolerance in C. sorokiniana, this alga also showed higher Zn biosorption capacity. Use of C. sorokiniana as a bio-remediator, could be considered.

Adaptation to tert-butyl hydroperoxide at a plasma membrane level in the fission yeast Schizosaccharomyces pombe parental strain and its t-BuOOH-resistant mutant.

The one‐gene mutant hyd1‐190 of the fission yeast Schizosaccharomyces pombe displayed four‐fold resistance to tert‐butyl hydroperoxide (t‐BuOOH) in comparison with its parental strain hyd+. The cells of hyd1‐190 exhibited a quantitative alteration in the sterol content and hence in the fatty acid composition of the plasma membrane, reflected in a two‐fold amphotericin B sensitivity, increased rigidity of the plasma membrane, revealed by an elevated (Δ7.9 °C) phase‐transition temperature, measured by means of electron paramagnetic resonance spectroscopy, and a significantly decreased uptake of glycerol. Treatment of the strains with a subinhibitory concentration (0.2 mM) of t‐BuOOH induced adaptation via modification of the sterol and fatty acid compositions, resulting in increased (Δ3.95 °C) and decreased (Δ6.83 °C) phase‐transition temperatures of the hyd+ and hyd1‐190 strains, respectively, in order to defend the cells against the consequences of t‐BuOOH‐induced external oxidative stress. However, in contrast with hyd+, hyd1‐190 lacks the ability to adapt to t‐BuOOH at a cell level.

Anti-inflammatory, antioxidant and antiangiogenic activities of diosgenin isolated from traditional medicinal plant, Costus speciosus (Koen ex.Retz.) Sm

Abstract Costus speciosus is an important medicinal plant widely used in several indigenous medicinal formulations. The present study was conducted to evaluate the in vitro anti-inflammatory, antioxidant and antiangiogenic activities of diosgenin isolated from C. speciosus. The diosgenin was isolated from C. speciosus by HPTLC and its biological activities were studied by different protocols. The results demonstrated that LPS stimulated TNF-α generation in RAW 264.7 macrophage culture supernatant up to 3.7-fold of the control and that sample treatment (50 μg/mL) resulted in a highly significant inhibitory effect on LPS-stimulated TNF-α (p < 0.01) in a similar manner to methotrexate inhibitory effect. The tested sample possessed an effective antioxidant scavenging affinity against DPPH radicals as compared with the standard antioxidant activity of vitamin C. The results presented here may suggest that diosgenin isolated from C. speciosus possess anticancer, apoptotic and inhibitory effects on cell proliferation.

Sensitivity of two green microalgae to copper stress: Growth, oxidative and antioxidants analyses

Depending on species, heavy metals, including copper (Cu), differentially affect algal growth and metabolism. Here, we aim to evaluate the differential responses of two green microalgae, Chlorella sorokiniana and Scenedesmus acuminatus, exposed to sub-lethal doses of Cu (25 and 50µM, respectively) for 7 days. The changes in growth, oxidative damage markers, and antioxidants were analysed. We found that S. acuminatus could acclimatise during long-term exposure to Cu stress. S. acuminatus accumulated lower Cu content and showed a slight decrease in H2O2 levels when compared to C. sorokiniana. Cu stress induced membrane damage in the two microalgae species, however, this increase was slightly lower in S. acuminatus. To mitigate Cu stress impact, C. sorkiniana markedly increased proline, polyphenols, flavonoids, tocopherols, glutathione levels, as well as the activities of GST, APX, GR and SOD enzymes, which could explain less-stress sensitivity. On the other hand, S. acuminatus exhibited significant increases in proline, polyphenol, and tocopherol contents. Activity levels of POX, APX, GR and SOD enzymes, were also increased. These results suggest that the two microalgae differentially induced the antioxidant defence system to neutralise the oxidative damage induced by Cu stress. This study also provided new data for Cu tolerance and Cu removal abilities of two microalgal species, which commonly exist in surface water bodies, where low Cu uptake and efficient antioxidant defence system protected S. acuminatus against oxidative stress induced by Cu stress. This makes it feasible for treatment of Cu contaminated waters.

Rapid identification of Pseudomonas aeruginosa by pulsed-field gel electrophoresis

Twenty clinical Pseudomonas aeruginosa isolates recovered from patients admitted to The General Hospital in Ismailia Governorate (Egypt) were examined in this study. We analysed P. aeruginosa ATCC 9027 (as a control strain) and 19 of the isolates after digestion with SpeI restriction endonuclease. After this we conducted a pulsed-field gel electrophoresis (PFGE) and typed the obtained 10 unique patterns, designated as A, A1, B, B1, C, C1, D, D1, E and F. We evaluated the genetic relatedness between all strains, based on ≥87% band identity. As a result, the isolates were grouped in the 10 clusters as follows: patterns A, A1, B, B1, C contained two strains each and patterns C1, D, D1, E contained a single strain each; the five remaining strains were closely related (genomic pattern F). One isolate belonged to antibiotype ‘b’. The genotype patterns of the P. aeruginosa ATCC 9027 control strain and isolate no. 11 were closely related and had two different antibiotypes ‘d’ and ‘c’, respectively.