Agarase Production by Marine Pseudoalteromonas sp. MHS: Optimization, and Purification

Agar is an essential polysaccharide that has been utilized in numerous fields. Many kinds of literature have been published regarding agarolytic microorganisms’ isolation and agarases biochemical studies. In this search, a local marine agarolytic bacterium associated with marine alga Ulva lactuca surface was isolated and identified as Pseudoalteromonas sp. MHS. The agarase production was parallel to the growth of Pseudoalteromonas sp. MHS as cells displayed a lag phase (2 h), subsequently an exponential growth that prolonged till 10 h where maximum growth (OD550nm = 3.9) was achieved. The enzyme activity increased rapidly as cells increased exponentially where the maximum activity of 0.22 U/mL was achieved after 8h and remained constant till 12 h during the stationary phase of growth. Agarase production was optimized using Plackett-Burman statistical design by measuring enzyme activity as a response and the design was validated using a verification experiment; the activity of the enzyme increased from 0.22 U/mL to 0.29 U/mL. Pseudoalteromonas sp. MHS agarase was partially purified and its molecular weight (MW) was determined by SDSPAGE (15-25 kDa). Agarase showed approximately 94% of its activity at 40 °C. The enzyme stability decreased as the temperature increased; the enzyme could retain about 98, 90, 80, 75, and 60% of its activity at 20, 30, 40, 50, and 60 °C, respectively. Biomass of the red alga Pterocladia capillacea proved to be a suitable substrate for agarase production using Pseudoalteromonas sp. MHS; the enzyme activity recorded after 24 h of incubation was 0.35 U/mL compared to 0.29 U/mL from the optimized medium

Phytochemical studies on essential oils of Pinus pinaster Aiton and evaluation of their biological activities

This study focus on the analysis of the chemical composition of the aerial parts essential oils (Eos) (needles, cones and branches) of Tunisian P. pinaster Aiton, and to evaluate their antioxidant activities, their inhibition toward germination and seedling growth of weeds and to assess their antifungal activities against phytopathogenic fungi. Eos were obtained by hydrodistillation and analyzed by GC and GC/MS analysis. A total of 27, 25, and 15 compounds were identified respectively in needles, cones and branches. All analyzed oils were rich in hydrocarbonated monoterpenes (32.57-90.48%). α-pinene (25.11-80.95%), β-pinene (1.86-33.12%) and β-caryophyllene (0.28-21.34%) were the dominant compounds in the volatile oils. All tested samples exhibited interesting antioxidant activities. The phytotoxicity of Eos was evaluated against tow weeds: Sinapis arvensis L. and Phalaris canariensis L. and one cultivated specie Triticum tirgidum L. The antifungal activity was investigated in vitro using five targeted fungal strains. Tested samples were differently effective toward tested plants and target fungi depending on the variability of their chemical compositions. All sample oils showed a significant phytotoxic effects and needles oils exhibited the highest herbicidal effects against all tested species. The highest fungitoxic properties were obtained with needles and cones Eos against all fungi

THE CHRONIC EFFECT OF FORCE-FEEDING (ORAL GAVAGE) ADMINISTRATION OF ASPARTAME ON WISTAR RATS (NEPHROTOXICITY AND NEUROBEHAVIORAL TROUBLES)

Background: This study was performed to see the effect of chronic administration by gavage of aspartame on kidneys and behavior in Wistar rats. Methods: In this study, 28 Wistar rats were used, divided into 04 groups including a control group treated with distilled water and three other groups treated with aspartame at different doses (40 mg / kg, 60 mg / kg, 1000 mg / kg body weight) for 90 days orally (gastric gavage). Results: A highly significant increase (p <0,001) of blood urea level ASP 3 group compared to the ASP1 group (ADI Acceptable Daily Intake) , however we observe a highly significant reduction in blood creatinine level (p <0, 01) as compared to the ASP1 tolerated daily intake group. In the open field test, we notice highly significant decrease (p <0,01) in the ASP3 group treated with the 1000 mg per kg body weight dose ASP 3 compared to the group treated with the 40 mg / kg bw dose or the ADI ( Acceptable Daily Intake) ASP1. The histopathological study of kidneys showed multiple vascular congestion with inflammatory infiltration in Group ASP3 compared to the control. Conclusion: The chronic administarion of aspartame by gavage on Wistar rats causes kidney damage and neurobehavioral troubles

Essential Oils and Biological Activities of <i>Eucalyptus falcata</i>, <i>E. sideroxylon</i> and <i>E. citriodora</i> Growing in Tunisia

Many plants are able to synthesize essential oils (EOs), which play key roles in defense against weeds, fungi and pests. This study aims to analyze the chemical composition and to highlight the antioxidant, antimicrobial and phytotoxic properties of the EOs from Eucalyptus falcata, E. sideroxylon and E. citriodora growing in Tunisia. EOs were analyzed by gas chromatography coupled to mass spectrometry (GC/MS) and their antioxidant properties were determined by total antioxidant capacity (TAC), DPPH and ABTS assays. The phytotoxic potential was assessed against weeds (Sinapis arvensis, Phalaris canariensis) and durum wheat crop (Triticum durum) and compared to chemical herbicide glyphosate. The antifungal activity was investigated in vitro against eight target fungal strains. All EOs displayed a specific richness in oxygenated monoterpenes (51.3–90%) and oxygenated sesquiterpenes (4.8–29.4%), and 1,8-cineole, citronellal, citronellol, trans-pinocarveol, globulol, spathulenol and citronellyl acetate were the main constituents. Eucalyptus EOs exhibited remarkable antioxidant activity and E. citriodora oil exhibited significant activity when compared with E. falcata and E. sideroxylon EOs. The phytotoxic potential of the tested oils had different efficacy on seed germination and the growth of seedlings and varied among tested herbs and their chemical composition variability. Their effectiveness was better than that of glyphosate. At the post-emergence stage, symptoms of chlorosis and necrosis were observed. Furthermore, a decrease in chlorophyll and relative water content, electrolyte leakage and high levels of MDA and proline were indicators of the oxidative effects of EOs and their effectiveness as bioherbicides. Moreover, all the EOs exhibited moderate fungitoxic properties against all the tested fungal strains. Therefore, according to the obtained results, Eucalyptus EOs could have potential application as natural pesticides

Correlation Between Chemical Composition and Antibacterial Activity of Essential Oils from Fifteen Eucalyptus Species Growing in the Korbous and Jbel Abderrahman Arboreta (North East Tunisia)

The essential oils of fifteen Eucalyptus species harvested from the Jbel Abderrahman and Korbous arboreta (North East Tunisia) were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major components as identified by GC/FID and GC/MS were selected for a study of the chemical and biological activity variability. The main one was 1,8-cineole, followed by spathulenol, trans-pinocarveol, α-pinene, p-cymene, globulol, cryptone, β-phellandrene, viridiflorol, borneol, limonene and isospathulenol. The chemical principal component analysis identified five species groups and subgroups, where each group constituted a chemotype, however that of the values of zone diameter of the inhibition (zdi) identified six groups of Eucalyptus oils, characterized by their antibacterial inhibition ability. The strongest activity was shown by E. platypus oil against Enterococcus faecalis and by E. lamannii oil against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. A correlation between the levels of some major components and the antibacterial activities was observed