Correlation between nitrogen fixation rate and alginate productivity of an indigenous Azotobacter vinelandii from Iran

Azotobacter vinelandii, a gamma-proteobacterium, is an obligate aerobic free-living gramnegative soil bacterium capable of fixing nitrogen. Oxygen transfer rate into the cell is reduced by the increase of alginate concentrations during the course of A. vinelandii cultivation. This phenomenon provides a low intracellular oxygen concentration needed for nitrogenase activity. The aim of this study was to design a simple strategy to explain the alginate production, cell growth and nitrogenase activity correlation in A. vinelandii under aerobic conditions. Thirty-five different soil samples were taken from the rhizosphere of agricultural crops of Iran. Enrichment and isolation strategies were employed for microbial isolation. Physiological and biochemical characteristics were determined. Molecular identification was performed using selective nifH-g1 primers. Alginate production and nitrogenase activity assay by each isolate of Azotobacter were carried out. Bacterial growth, alginate production and Nitrogenase activity were conducted by time-coursed quantitative measurements. Total of 26 isolates were selected after enrichment, isolation, and screening. The isolate was identified by molecular tests as A. vinelandii. The highest alginate productions of 1.02 g/l and 0.91g/l were noted after 4 days in 8 isolates, cell biomass of which were estimated 4.88-5.26 g/l. Six of 8 isolates were able to fix atmospheric N[2] on nitrogen-free medium. Rates obtained in isolates were in the range of 12.1 to 326.4 nmol C[2]H[4] h[-1] vial[-1]. Nitrogen fixation and alginate production yielded significant and positive Pearson's correlation coefficient of R[2] = 0.760, p tilde 0.02. Finally association between bacterial growth, alginate production and nitrogenase activity almost noticeable yielded significant and positive Pearson's correlation coefficient R2 = 0.723, p tilde 0.04.

Comparison of ferrous ion chelating, free radical scavenging and anti tyrosinase properties of Thymus daenensis essential oil with commercial thyme oil and thymol

Utilization of plants as antioxidants in food processing has a potential for substitution of synthetic antioxidants. In the present work, some unexplored biological activities of Thymus daenensis, commercial thyme essential oils and thymol were comparatively studied. Ferrous ion chelating was assessed by spectrophotometry by mixing the essential oils with diluted FeSO[4] followed by addition of ferrozine. Antioxidative properties were assessed by beta carotene bleaching and 2,2-diphenyl-l-picrylhydrazyl [DPPH] free radical scavenging tests. Gallic acid equivalent of ferric reduction was carried out using FeCl[3]. Super oxide anion radical scavenging was determined using xanthine oxidase and anti tyrosinase inhibitory activity was determined by a spectrophotometry method using a modified dopachrome method with L-DOPA as the substrate. Chelating reaction of T. daenensis oil was dose dependent, and its super oxide anion radical scavenging property was higher than the commercial oil. Lipid peroxidation inhibition by T. daenensis oil was stronger and those of the commercial oil and thymol were approximately equal. DPPH free radical scavenging property of T. daenensis oil was higher than trolox, butylated hydroxytoluene and anisol [BHT and BHA]. Ferric-reducing antioxidant power [FRAP] of T. daenensis oil was greater. The total phenolics anti tyrosinase IC[50] were also determined. The results point to the nutritional value of these plants in preventing formation of toxic reactive oxygen species, and show that Thymus daenensis, as a good antioxidant, can directly scavenge free radicals. The results from biological properties of Thymus daenensis are indicative of its potentials for use in food and drug industries

Lipid peroxidation inhibition, superoxide anion and nitric oxide radical scavenging properties of thymus daenensis and anethum graveolens essential oils

Safety and efficacy of the synthetic antioxidants used in the food industry are frequently questioned because such antioxidants are unstable and highly volatile, therefore, interest in finding naturally occurring antioxidants that have the potential to protect human beings from damage induced by oxidative stress has intensified. Bioactivities of Thymus daenensis and Anethum graveolens essential oils with special reference to their antioxidative properties are studied. Total phenolic content [TPC], lipid peroxidation inhibition [LPI], ferrous-ion chelating [FIC], superoxide anion and nitric oxide radical scavenging, and tyrosinase inhibition activities of the essential oils were determined. TPC of T. daenensis and A. graveolens oils were 644.07 +/- 6.79 and 174.91 +/- 2.05 mg GAE/100 g. T. daenensis and A. graveolens oils showed the highest LPI activity with FICs of 63.28 +/- 0.21 and 70.22 +/- 1.9 percent respectively. Superoxide anion and nitric oxide radical scavenging activities of the above oils had IC[50] of 0.013, 0.001 and 0.005, 0.0014 mg, respectively. A. graveolens oil showed 6 fold higher anti - tyrosinase activity than T. daenensis oil. There was not correlation between lipid peroxidation or ferrous ion chelating activities with total phenolics implying that the oils contain chelating ligands. The effects of antioxidant phytochemicals in the biological systems are ascribed on their ability to scavenge radicals, chelating metals, activate the antioxidant enzymes, and to inhibit the oxidases. T. daenensis and A. graveolens oils have good commercial potential in both food processing and cosmetic industries

Phytobiological characteristics of Rosa hemisphaerica Herrm. extract

Roses are one of the most important groups of ornamental plants referred to as the queen of flowers and their fruits and flowers are used in a wide variety of food, nutritional products and different traditional medicines. A large diversity is expected to be found in Iranian Damask rose landraces with different biological properties. The antibacterial, antioxidant and cytotoxicity of methanolic and aqueous extracts of Rosa hemisphaerica Herrm. were studied. Methods: The agar disc diffusion method was employed for the determination of antimicrobial activities. Total phenol contents of both extracts were estimated. Antioxidative properties of the extracts were determined by bleaching of beta carotene or 2, 20-diphenylpicrylhydrazyl [DPPH]. The Ferric-Reducing Antioxidant Power [FRAP] was expressed as gallic acid equivalents. Cytooxicity of the extracts were tested using Hela and human healthy peripheral blood cells. of various microorganisms tested, only S. aureus was found susceptible. The total phenol contents of the methanolic and aqueous extracts were 138.33 +/- 11.37and 129.67 +/- 4.51 micro g Gallic acid equivalent/mg sample respectively. DPPH scavenging and lipid peroxidation inhibition effects were higher than those of the synthetic antioxidants. Ferric-reducing antioxidant power [FRAP] of the methanolic and aqueous extracts were determined as 96.134 +/4.25 mg/g and 98.63 +/- 2.51 mg/g respectively. The 50% cytotoxic concentrations were found to be 0.327 mg/ml 0.177 mg/ml for Hela cells and human lymphocytes respectively. It can be concluded from the above results that R. hemisphaerica extract exhibited antimicrobial activity only against S. aureus. The extracts provided better antioxidative activity as compared with synthetic antioxidants. The extracts were toxic to the Hela cells as well as human lymphocytes. Hence, the R. hemisphaerica extract may be exploited as a natural antioxidant and health promoting agent

Effects of sub-inhibitory concentrations of essential oils of Mentha spicata and Cumminum cyminum on virulence factors of Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of important opportunistic pathogen, that cases serious infections. It produces many virulence factors, and this bacterium usually is resistance against antimicrobial agents. The aim of this study was evaluate the effects of sub-MICs of essential oils of Mentha spicata and Cumminum cyminum on alginate production, biofilm formation, swimming, twitching and adhesion in P. aeruginosa 8821M. Minimal inhibitory concentrations [MIC] of essential oils of Mentha spicata and Cumminum cyminum were determined by macrodilution method. Alginate production, biofilm formation, swimming, twitching and adhesion in the present of sub-MICs [1/2, 1/4 and 1/8 MIC] of essential oils were determined in mucoid P. aeruginosa 8821M and compared with controls. The MICs of essential oils against P. aeruginosa for M. spicata and C. cyminum oils were obtained 16 and 32 micro g/ml respectively. The results show that all oils at 1/2 and 1/4 MICs were significantly reduced all tested virulence factors. At 1/8 MICs, M. spicata had effect just on adhesion but C. cyminum had effect on Alginate production, biofilm formation, swimming and twitching. This study showed that sub-MIC levels of M. spicata and C. cyminum essential oils affected alginate production, biofilm formation, swimming, twitching and adhesion in P. aeruginosa 8821M and it is probable to use of these medicinal plants for treating

Phytoprevention of aflatoxin production

Consumption of mycotoxic foods is associated with several cases of human poisoning, or mycotoxicosis, sometimes resulting in death. Phytopreventive inhibition of Aspergillus parasiticus growth and its aflatoxin production by the essential oils extracted from Thymus kotschyanus Boiss and Hohen and Zataria multiflora Boiss. is reported in this study. Minimal inhibitory concentration [MIC], minimal fungicidal concentration [MFC] and fungicidal kinetics of the oils were determined and compared with each other. The oils from the above mentioned plants were found to be strongly fungicidal and inhibitory to aflatoxin production. Both oils inhibited aflatoxin B[1] [AFB[1]] production by A.parasiticus. T. kotschyanus and Z. multiflora oils at 25 ppm concentration, reduced AFB1 levels by 100% and 47.87% respectively. Aflatoxin production was significantly inhibited at lower than fungistatic concentration of both oils. The analysis of oils by GC and GC/MS led to identification of 27 and 22 components in T. kotschyanus and Z. multiflora Boiss. respectively which were very similar to each other. Prevention of fungal growth and aflatoxin production by natural compounds is recom

Effect of pomegranate fruit juice and seed oil on serum lipid levels and atherosclerosis development in hypercholesterolemic rabbits

Pomegranate [Punica granatum L.] is a drought tolerant fruit-bearing deciduous shrub native to Iran. It is widely cultivated in dry areas of Iran. Pomegranate fruit juice contains a wide range of polyphenolic metabolites, especially punicalagins with powerful antioxidative properties. Pomegranate seed oil is a unique natural product and a rich source of conjugated fatty acids. The aim of this study was to investigate the pharmacological effects of fruit juice and seed oil of pomegranate on serum lipid levels of hypercholesterolemic rabbits and development of atherosclerosis on their aortas. Fourthly two males and six months aged white New Zealand rabbits [1.7 -2 kg] were randomly assigned to six equal groups and caged in the same environmental condition. One group was fed on regular animal house rabbit chew. Five other groups fed with high cholesterol diet [1% cholesterol]. One group kept as control and other 4 groups fed on same diet supplemented with 1% and 2% doses of pomegranate fruit juice or seed oil. The whole experiment lasted 2 months. At the end of the study [after 2 months] the biochemical analysis of serum lipids and pathological evaluation of atherosclerotic plaque of aortas were performed. Results of biochemical analyses showed that administration of fruit juice and seed oil at both doses did not significantly affect the level of serum lipids profile of hypercholesterolemic rabbits. Pathological data analysis showed that treatments of rabbits with fruit juice and seed oil at both doses significantly reduced aortic atherosclerotic plaque formation. Pomegranate fruit juice and seed oil administration inhibited atherosclerosis development in hypercholesterolemic rabbit's aortas without any significant effects on lipid profile

Effect of silymarin, The seed extract of cultivated and endemic silbum marianum [L.] gaertn., On serum lipid levels and atherosclerosis development in hypercholestrolemic rabbits

Silymarin, the seed extract of silybum marianum [L] gaertn., contains flavonolignan compounds with powerful antioxidant properties. The favourable effects of herbal medicine with antioxidant properties on lipid profile have been reported in several experimental studies. The aim of this research was to investigate the effects of cultivated and endemic silymarins and levostatin with antioxidant properties on serum lipoproteins levels and atherosclerosis development in hypercholesterolemic rabbits. Hypercholesterolemic foods were fed to 5 groups of 8 rabbits each for 60 days one group negative control, second group received levostatin [10mg/kg] and other two groups received cultivated and endemic silymarins [200 mg/kg] daily one hour before feeding. The last group did not receive any drugs [positive control] The fasting blood total cholesterol LDL and HDL-cholesterol and triglyicride levels were determind before starting the experiments and also after 30 and 60 days during the study. At the end of the study rabbits were killed and the extent of aortic atherosclerotic plaque were determined. Results showed that, levostatin. Cultivated and endemic silymarins caused a significant decrease in fasting serum cholesterol and LDL-cholesterol compared to control group. HDL-cholestrol increased and triglyceride level was significant decreased in cultivated and endemic silymarins treated groups, as compared to positive control group. In addition, atherosclerotic plaque development was significantly decreased in levostatin, cultivated and endemic silymarins treated groups. Treatment of hypercholesterolemic rabbits with levostatin, cultivated and endemic silymarins showed favourable effects on serum lipid profile, as well as atherosclerotic plaque development