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Showing 38 results for Subject: Microbiology

Narges Najjarpour, Masoud Mashadi Akbar Boujar,
Volume 3, Issue 1 (6-2016)
Abstract

Carnosic acid and Rosmarinic acid are family of polyphenols that are found in Rosmary plant. They have property biological behaviors such as anti-cancer, anti-viral and anti-oxidants. This study compared the effects of these two compounds based on ceramide metabolism in cell line of Hep- G2. In this experimental study, Hep-G2 cells were cultured in DMEM supplemented containing bovine fetal serum and antibiotics. Cells with double dilution were then cultured from  tow substance Carnosic acid and Rosmarinic acid from concentrations  0 to 70 µM for 24 h and viability of cells was determined by MTT method.  Spectrophotometer was used to measure of caspase-3 activity.To measure the level of ceramide, a recombinant ceramidase acid enzyme and naphthalene-2,3-dialdehyde, which is fluorescent and is connected to sphingosine resulted from ceramidase acid, were added to the cell extract and was ultimately determined by HPLC. In this study also activity of ensymes as sphingomylinase, acid ceramidase, glucosyl ceramide synthase was measured. Carnosic acid increased cell viability dose-dependent in Hep-G2 cells by reducing ceramide levels and decreasing activity of ensymes as caspse-3, sphingomylinase, glucosyl ceramide synthase and  increasing activity of the enzyme acid ceramidase. Rosmarinic acid in concentrations of up to 50 µM decreased cell viability by increasing ceramide levels and activity of caspse-3, sphingomylinase and decreasing activity of  enzymes as acid ceramidese and glucosyl ceramide synthase. Also this substance in concentrations of up to 40 µM caused increasing activity of caspse-3 enzyme. Although in most cases, polyphenols have resulted in induction of apoptosis and decreased cell viability, but in some cases they have inversely affected and caused cell growth.


Zahra Sadat Mirei, Minoo Sadri, Ali Salimi,
Volume 3, Issue 3 (12-2016)
Abstract

Main agent orange-red coloured pigment of henna is a molecule called Lawson which is responsible for anti-microbial, anti-tumor, anti-inflammatory and analgesic activity. Chitosan is a biopolymer with high strength, biocom-patibility and biodegradability, non-toxicity and antimicrobial properties. Electrospinning is a method of producing su-bmicron polymeric fibers with high porosity and high surface/volume ratio. In this study, electrospinning of chitos-an/polyethylene oxide (Chit/PEO) nanofibers with the addition of henna extract to create nanofibers with antimicrobial properties were examined. Nanofibers was constructed by electrospinning of polymeric solution with proper size and si-ze distribution of Chit/PEO with a ratio 90/10. Then, Lawsonia inermis (henna) extract as an additive to Chit/PEO co-polymer was added and electrospined on the surface. After characterization of nanofibers using SEM, the antimicrobial properties of polymeric solution and nanofibers were investigated. The scanning electron micrographs showed that Ch-it/PEO nanofibres with a low percentage of henna extract have suitable diameters and size distribution similar to Ch-it/PEO nanofibres without adding extract. In bacteriological studies, it was found that chitosan polymer solutions cont-aining 1% of henna extract has bactericidal properties against Staphylococcus aureus, Escherichia coli and Pseudo-monas aeruginosa bacteries better than polymer chitosan solution without adding the extract.


, Farhad Valizadegan, Mohammadreza Zarrindast,
Volume 4, Issue 2 (9-2017)
Abstract

Septohippocampal system plays an important role in regulating fear and anxiety behaviors. In this study, the effects of histamine injected into the dorsal hippocampus and opioidergic agents into medial septum on the anxiety-like behaviors in rats were analyzed, using the Elevated Plus-Maze (EPM) test. Injection of 1 and 5 μg/rat histamine into dorsal hippocampus had no effect on anxiety-like behavior, while injection of 10 μg/rat histamine increased the percentage of open arm time (%OAT) and open arm entry (%OAE), which indicated the anxiolytic effects of histamine. Microinjection of morphine, μ-opioid receptor agonist, into the medial septum (1μg/rat) increased the (%OAT) and (%OAE). Doses of 0.25, 0.5 μg/rat morphine had no effect on anxiety. Co-administration of histamine ineffective dose (1μg/rat) to the dorsal hippocampus and ineffective dose of morphine (0.25µg/rat) to the medial septum increased the (%OAT) and (%OAE). Subsequently, injection of different doses of naloxone (1, 2, 4 µg/rat), as an opioid receptor antagonist, into the medial septum in the presence and absence of an effective dose of histamine (10 µg/rat) in the dorsal hippocampus, was studied. Injection of naloxone (4 µg/rat) into medial septum decreased the (%OAT) and (%OAE), but did not alter the locomotor activity, which indicated the anxiogenic effects of naloxone. Simultaneous injection of histamine (10 µg/rat) into dorsal hippocampus with doses of naloxone (1, 2, 4 µg/rat) into the medial septum, indicate anxiolytic effects and increased %OAT and %OAE in Elevated Plus Maze, although when the dose of naloxone was 4μg/rat, this effect was less observed. The results indicate that hippocampus histaminergic system interact with medial septum opioidergic system and the interaction of these systems modulates anxiety behavior.
Saide Afrisham, Arastoo Badoei-Delfard, Abdolhamid Namaki Shoushtari, Zahra Karami, Saeid Malek-Abadi,
Volume 4, Issue 4 (3-2018)
Abstract

Alpha-amylases are the most important amylases used in industry. Among them, thermophilic alpha-amylases are of particular importance, which is due to their activity and stability in high temperatures. These enzymes produced by thermophile micro-organisms including bacteria. These thermophilic alpha-amylases are used in various industries such as processing of starch as well as production of detergents and biofuels. In this research, the bacteria which produce the thermophilic alpha-amylases were isolated and characterized in hot springs of Gorooh village in Kerman province. According to the results of screening on the specific liquid and solid media, AT59 was selected as the best strain. Morphological and biochemical characterization of the isolated strain indicated that it belonged to Bacillus sp. and was gram-positive, catalase positive, casein hydrolyzing and acid producing from lactose and sucrose. The results obtained from the optimization of the enzyme production medium showed that among the carbon, nitrogen and ion sources investigated, starch (1 gr/l), gelatin (2 g/l) and magnesium sulfate (1 g/l) had the most increasing effect on the production of AT59 alpha-amylase. Moreover, the highest enzyme production was obtained at pH 5. This enzyme also demonstrated the highest degree of activity and stability in 80 and 70 ℃, respectively. These findings suggested that this enzyme has a considerable potential for use in starch industry.
 

 
 
Karim Mahnam, Fatemeh Mirahmadi Babaheidari,
Volume 5, Issue 2 (9-2018)
Abstract

The XIAP protein is a member of apoptosis proteins family. The XIAP protein plays a central role in the inhibition of apoptosis and consists of three Baculoviral IAP Repeat domains. The BIR3 domain binds directly to the N-terminal of caspase-9 and therefore it inhibits apoptosis. N-terminal tetrapeptide region of SMAC protein can bind to BIR3, inhibit it and subsequently induce apoptosis. In this study, fifteen tetrapeptides were docked into the BIR3 domain and then 10 ns molecular dynamics simulations were performed on each of the BIR3-peptide complex obtained from docking. MM/PBSA method was subsequently used to calculate the binding free energy of peptides to BIR3. The results of MM/PBSA method were in good coordination with docking and existing expermental results.  The results showed the most potent peptides with the lowest binding free energy for binding to BIR3 included ATPF, AKPW and ARPF peptides. Also, investigation of bonds between these peptides and BIR3 domain in the final structure of complexes showed that Leu 307, Thr 308, Glu 314 and Tyr 324 of the BIR3 domain were essential for binding of peptides. Energy decomposition results for binding these peptides to the BIR3 domain during MD simulation was inconsistent with previous results and approved the roles of the same residues. The higher affinity of these peptides relative to native peptide (AVPI) and comparing them with other peptides revealed that the existence of positive charge in the second position and the existence of the aromatic group in the fourth position led to more binding affinity.

Hesane Hassanpour, Mohammad Shokrzadeh Lamuki, Reza Tabari, Fatemeh Rezaee, Fatereh Rezaee,
Volume 5, Issue 2 (9-2018)
Abstract

With the increase of cancer disease and the side-effects of the current treatments, researchers are attempting to find methods with less side-effect. The fern Adiantum capillus-veneris L. has triterpenoid compounds which have anti-tumor characteristics. This study aims to investigate the fatal effect of the extract of this plant on breast cancer (MCF-7) and normal (MRC-5) cell lines using MTT method. A. capillus-veneris specimens were collected from Marzoon Abad Village and were dried at the temperature of 40° C by the use of Soxhlet and Ethanol % 96. Hydroalcoholic extract was produced from the aerial and underground parts of this plant and 3 fractions, i.e., Hexane, Chloroform and Ethyl acetate, were prepared from the extract. The compounds of the plant extract were identified by GC-Mass. The results demonstrate the presence of polyphenolic compounds, terpenoid, fatty acids, wax, alkaloid, N-oxide and fibers, with strong antioxidant effect. The results of the MTT test proved that this extract had a dose-depending fatal effect on the MCF-7 cells and is capable of eradicating the cancer cells. On the other hand, its effect on cancer cells is more than its effect on normal cells. Also, IC50 in both of cell lines induced by the extracts of aerial and underground parts showed a significant difference. The fatal characteristics of the extract are comparable with the cisplatin anti-cancer drug.
 
Seyedeh Mahdieh Sadadt, Zahra Hajihassan, Mohammad Barshan-Tashnizi, Mehri Abdi,
Volume 5, Issue 3 (12-2018)
Abstract

Nerve growth factor (NGF) is a neurotrophic factor that is functional in the survival, maintenance and differentiation of nervous system cells. This protein has three subunits, of which the beta subunit has the main activity. Its structure consists of a cysteine knot motif made up of beta strands linked by disulfide bonds. It can be used as a therapeutic agent in the treatment of many diseases. As NGF extracted from natural sources is unsuitable for therapeutic goals, many studies have attempted to produce recombinant β-NGF. In this study, Trigger Factor (TF) chaperone was expressed simultaneously with β-NGF in E. coli in order to obtain increased yield of soluble recombinant human β-NGF.  For this purpose, pET39b (+)::β-NGF and chaperone plasmid pTf16 were transferred to E.coli (DE3 strain). After the induction of each promoter, the total proteins and periplasmic proteins were extracted. To confirm the effects of TF on total protein and soluble β-NGF expression level, Bradford and Dot blot techniques and ImageJ software were used. Then, β-NGF was purified using affinity chromatography column (Ni+2-NTA). Also, the PC12 cells were treated with the protein for one week in order to study the function of purified NGF. Our data indicated that co-expression of TF could increase the soluble and periplasmic production of β-NGF but not total proteins. Also, the treatment of PC12 cell line with purified β-NGF, co-expressed with TF chaperone, showed differentiation of these cells to nerve cells. This indicated that the purified NGF is fully functional. Our data suggest that the co-expression of cytoplasmic chaperone (TF) with recombinant nerve growth factor might be an efficient approach to produce a proper quantity of soluble and active rhNGF.


Khadijeh Mahmoodi, Maneezheh Pakravan, Valiollah Mozaffarian,
Volume 5, Issue 3 (12-2018)
Abstract

The genus Zoegea L. belongs to Asteraceae family and has about 10 species in the world. This genus is considered to be an Irano-Turanian and Mediterranean element and is distributed in south-western and central Asia and in the central, southern, north-western and south-western parts of Iran as well. The subspecies classification of the genus is not consensus and various classifications could be found in different taxonomy resources. In this study various specimens from different regions of Iran were studied. In addition, anatomical and palynological characters were used to perform a cluster analysis in order to determine species groups. In the end, our results confirmed that Z. baldschuanica and Z. glabricaulis were distinct species.
 
 

 
Ensieh Salehghamari, Marzieh Hosseini, Fatemeh Taheri,
Volume 5, Issue 4 (3-2019)
Abstract

Saline soils are widely spread in Iran. These intact soils are a great source for the isolation of new bacteria with highly functional metabolites in biotechnology. Actinomycete strains were isolated on starch casein agar and ISP2 with different concentrations of sodium chloride (0, 5 and 10%) from treated soil samples. Pure colonies were cultured on a casein glycerol medium. After complete growth, the plates were covered with a thin layer of Muller Hinton Agar (1%) containing methicillin-resistant Staphylococcus aureus (MRSA). Active metabolites of selected strains were extracted and their antibacterial activities analyzed by agar well diffusion method. 38% of isolates produced antibiotics against the pathogen. The metabolites produced by act-2 and act-5 isolates, which had a more effective inhibition zone against MRSA, were extracted and anti MRSA activity of act-5 extract was shown. The antimicrobial activity of act-5 against other bacteria was also investigated and the bacterium was identified. In this study halophilic actinomycetes producing bioactive compounds were isolated from the saline soils of Qom and the anti-MRSA potential of their metabolites was investigated for the first time. The results of this study show the potential of saline soil actinomycetes for the production of useful metabolites.


 
Fatemeh Elmi, Zahra Etemadifar, Giti Emtiazi,
Volume 6, Issue 1 (5-2019)
Abstract

It is necessary to reduce the amount of sulfur in fossil fuels due to direct impact of the quality of these fuels on the environment. In this research, a novel fungus strain of Exophiala spinifera, namely FM, was used to desulfurize dibenzothiophene (DBT) as a model cyclic sulfur compounds in oil and fossil fuels. HPLC analysis indicated that the fungus was capable of reducing 99% of DBT concentration in BSM medium after seven days. This fungus utilized DBT as a sulfur source by co-metabolism reaction with other carbon sources such as glucose. Exophiala spinifera was inoculated in BSM medium containing DBT with various carbon sources including ethanol, glucose, succinate, and glycerol. This fungus had the highest growth and desulfurization capability on glucose as a carbon source after 96 h. E. spinifera had best growth and desulfurization rates in 0.3mM DBT. Optimum DBT desulfurization and growth rate of this fungus was observed at 26-30 oC. Suitable pH for the optimum growth and desulfurization activity of E. spinifera strain FM ranged 4-5.


Somayeh Farahmand, Faezeh Fatemi, Reza Hajihosseini,
Volume 6, Issue 1 (5-2019)
Abstract

In Acidithiobacillus ferrooxidans, the proteins present in the electron transfer pathway cause ferrous iron oxidation which leads to uranium extraction. The relationship between gene sequence and uranium extraction has not been investigated yet. Based on the changes in uranium extraction, the changes of rus gene sequence can reveal the direct and accurate role of this protein. For this purpose, a random mutation was induced in native Acidithiobacillus sp. FJ2 by two doses of 0.8% and 1% of DES. Then, the bacteria was transferred into a medium which contained 50% uranium ore to carry out the bioleaching process. After measuring the amount of the extracted uranium, iron, Eh and pH, genomic DNA was extracted to investigate the rusticyanin gene (rus) sequence sent for sequencing after performing PCR. Then, the wild-type gene sequence was compared with the mutant by Bioedit v7.2.5 software. The results showed that uranium extraction increased by mutant bacteria with DES 1% between 7-11 days in comparison with wild bacteria. However, there has been no change in the functional areas of the rusticyanin gene. It seems that DES affected other effective genes in the electron transport chain or regulatory areas, which required further studies.
 



 
Neshat Saffarzadeh, Hamid Moghimi,
Volume 6, Issue 1 (5-2019)
Abstract

Impranil DLN is a class of plastics belonging to the polyurethane family with high application in textile industries. The aim of this study was to evaluate the potential of native strain to degrade impranil DLN. In this study, yeast strains were isolated from different areas and purified in minimal medium containing 1% impranil. Isolate NS-10 was selected as the superior strain capable of degrading impranil and identified through PCR and ITS gene. Esterase, urease and protease assays were carried out for the superior strain. Finally, the biodegradation of impranil was investigated. In total, 40 yeast strains were isolated and isolate NS-10 was selected as a superior strain based on impranil removal assay. NS-10 strain was identified as Sarocladium kiliense with 100% homology. Enzymatic assays showed that the S.kiliense could produce esterase, urease and protease. In addition, it could produce significant clear zones on impranil plates. Degradation rate for impranil was 100% for 10 g/l within 14 days. Finally, S.kiliense was taken to medium containing pure polyurethane film and the capacity of degradation was investigated by the scanning electron microscopy. Our results indicated that S.kiliense is capable of degrading impranil. These results could contribute to a better insight into the mechanism of plastic biodegradation.
 
 


Razieh Sadat Solouki Nezhad, Hanieh Asaadi, Yaser Eshaghi Milasi, Sajjad Yazdansetad,
Volume 6, Issue 1 (5-2019)
Abstract

The production of pigments from bacteria is significant due to the low cost, high yield and ease of extract compared with other sources. Carotenoids are one of the most important pigments with antioxidant properties which are the precursor of vitamin A synthesis and have antibody overproduction ability, anti-tumor activity and inhibitory effect on the cardiovascular disease. The present study aimed to isolate and identify carotenoid-producing bacteria by high-performance liquid chromatography (HPLC) analysis of their carotenoid pigments. Twenty soil samples were collected from different regions of Tehran. After serial dilution each sample was cultured on BHI agar medium and incubated at 37°C. The pigment-producing bacteria were selected for further identification and their pigments were extracted by methanol. The screening was carried out at two levels: i) selection of the strains by visual color inspection, ii) analysis of the pigment extracts by UV-VIS spectroscopy and HPLC. The isolates were identified by phenotypic methods and their 16S rDNA gene was amplified by PCR method and sequenced. Staphylococcus epidermidis, Micrococcus aloeverae, Citricoccus alkalitolerans, Rhodococcus zopfii, Arthrobacter agilis, Dietzia natronolimnaea and Rhodococcus ruber were identified as carotenoid-producing strains. The highest rate of absorption was observed using UV-VIS analysis in Staphylococcus epidermidis and Dietzia natronolimnaea. The comparison of HPLC analysis with the standard β-carotene curve showed that the carotenoids were beta-carotene. Micro-organisms are a potential source in the production of pigments. In this study we introduced two genera of bacteria (Staphylococcus epidermidis and Dietzia natronolimnaea) with carotenoid-producing ability.
 
 


Mohsen Fatemi, Nasrin Mollania, Madjid Momeni-Moghaddam, Fatemeh Sadeghifar,
Volume 6, Issue 1 (5-2019)
Abstract

New properties of nano-materials have made nanotechnology the leading part of biology and medical sciences. Due to their various biomedical properties, iron-based magnetic nanoparticles (MNPs) have been highly considered by biological researchers. Nowadays, increasing resistance to antibiotics is a major problem in treating clinical infections. Finding new antibacterial agents is therefore essential for the treatment of resistant strains. In this study, the iron oxide MNPs were produced using culture-medium supernatant of a newly isolated bacterium to investigate the inhibitory effects of the NPs on strains with a major role in clinical infections. Biosynthesis of iron oxide MNPs were detected by UV-Vis spectroscopy and the average size of particles was estimated by dynamic light scattering technique. The anti-bacterial activity of these NPs against E. coli and S. aureus was investigated using methods for the calculation of bacterial sensitivity coefficient. In the presence of NPs, the highest sensitivity coefficient value was observed for E. coli in 1xMIC concentration. On the other hand, S. aureus showed the lowest value. The death rate of the two strains in contact with NPs followed the first order kinetic equation and the survival rate decreased with the increase of exposure time. The results of this study as well as the high functionality of iron oxide MNPs, make its application desirable in the prevention and treatment of clinical infections.

 


Maryam Khezri,
Volume 6, Issue 1 (5-2019)
Abstract

Bacterial communities are able to form complex and three-dimensional biofilm structures. Biofilm formation is an ancient and integral component of the prokaryotic life cycle and a key factor for survival in diverse niches. In biofilms, bacterial lifestyle changes from free-floating cells to sessile cells. Presence in biofilms gives new traits to bacteria, which distinguish them from free cells. The presence of bacteria in biofilms results in high resistance to antimicrobial treatments and oxygen deficiency. Biofilms are formed in response to different environmental signals and many genes are involved in their production. Biofilms can be problematic in fluid transfer pipelines, on medical devices, as well as implants in the patients’ bodies. However, they can be applied for useful purposes such as treating industrial and agricultural wastewater, bioremediation of heavy metals and in air pollution biofilter systems. The potential of forming biofilms in pathogenic bacteria is an advantage for their survival in unfavorable conditions, and cause a lot of problems in their removal as the bacteria show more resistant to antibiotics and chemical pesticides in biofilms compared with free living cells. The ability to form biofilms in plant-beneficial rhizobacteria used for plant disease biocontrol, plant growth promotion and the improvement of agricultural products quality is an important advantage especially in their mass production and commercializing process. Considering the importance of bacterial biofilms in human life, this paper evaluated the importance of biofilms from different aspects.
 
 
Farshad Darvishi,
Volume 6, Issue 2 (8-2019)
Abstract

Lipase is used in the production of foods, flavor enhancers, detergents, cosmetics and pharmaceuticals. A common impediment to the production of commercial enzymes is their low-stability aqueous solutions. In this study, the downstream process was investigated to obtain a stable spray-dried lipase powder of Yarrowia lipolytica. The enzyme solution samples were supplemented with different concentrations of Arabic gum and milk powder to spray-drying. Samples were dried in a pilot spray dryer at inlet and outlet temperatures of 175 and 85 °C, respectively, at a flow rate of 15 liters per hour. The best lipase powder obtained from spray-drying with 3% of Arabic gum and 9% of milk powder formulation as compared with other formulations. Results showed that spray-dried lipase powders of Y. lipolytica had a good yield suitable for various applications.
 
 


Mohsen Shahriari Moghadam, Behrooz Abtahi, Gholamhossein Ebrahimipour,
Volume 6, Issue 2 (8-2019)
Abstract

Organisms in different environmental conditions express different genes, which result in different protein expressions. These changes result from the adaptation of the organism to environmental conditions such as the presence of toxic substances. This study aimed to investigate the changes in protein expression in Celeribacter persicus SBU1 isolated from Nayband Bay mangrove forests, cultured in the medium containing phenanthrene as the sole source of carbon and energy. For this purpose, C. persicus SBU1 was cultured on mineral salt medium containing phenanthrene and sodium acetate as treatment and control, respectively. After the extraction of total protein, changes in protein expression were evaluated by SDS-PAGE. Proteins were identified by MALDI-TOF-TOF MS. After evaluating changes in protein content, two bands which showed greater variation in comparison with the control treatment (increased protein expression) were detected. The identified proteins included one ligand-gated channel protein and one unknown protein. In general, the results of this study showed significant changes in the protein content of C. persicus SBU1 after using phenanthrene. The up-regulation of ligand-gated channel protein signified the role of this protein in phenanthrene molecules transport in and out of the cells.

Mahnaz Nasre Taheri, Gholamhossein Ebrahimipour, Hossein Sadeghi,
Volume 6, Issue 3 (10-2019)
Abstract

Proteases are important industrial enzymes used in different areas of industry, mainly detergent, food and leather industries. In this study, novel alkaline protease-producing bacterium was isolated from Geinarje hot spring and examined for maximum protease activity to be utilized in washing-powder. The isolated bacterium was cultured in mineral salt medium including 2% Skim Milk. Proteolytic activity of supernatant was measured by caseinolytic method. The effects of pH, temperature, SDS, Tween 80 and EDTA on protease stability and activity were investigated. The detergent compatibility of protease was assayed. On the basis of phylogenetic analysis and morphological as well as biochemical tests, the isolate was identified as a new strain of Brevibacillus borstelensis capable of generating extracellular alkaline protease. The generated protease was determined as alkaline metallo-protease having high activity at 60 oC and pH 9. Moreover, the alkaline protease was stable in the presence of SDS, Tween 80 and H2O2. It is compatible with commercial detergents. Finding proteases capable of degrading proteins in extreme environment (i.e. alkaline pH, high temperature and presence of surfactants) is valuable in biotechnological and industrial practices. Therefore, it can be utilized in detergent formulation in the future.

 


Asghar Mosleh Arany, Navid Nemati, Hengame Zandi, Mostafa Naderi,
Volume 6, Issue 4 (1-2020)
Abstract

The aim of this study was to evaluate the antibacterial activity of the water extracts of three species of Salvia (S. perspolitana, S. palaestina, S. bracteata) on Staphylococcus aureus, Escherichia coli and Pseudomonas aeroginosa. The antibacterial activity of water extracts of the studied species on the bacterial strains was examined using well diffusion method and minimum inhibitory concentration (MIC). Results showed that only S. bracteata formed growth inhibitory zone (9 mm) on Staphylococcus aureus. The extracts of all three plants formed growth inhibitory zone on E.coli and P. aeroginosa. The extract of S. bracteata was more effective than that of the other species. Results for MIC also showed that the extracts of S. perspolitana had the lowest effect on St. aureus and its MIC was observed in a concentration of 1024 µg/ml. The extracts of this species had the inhibitory effect in a concentration of 256 µg/ml. The uppermost inhibitory effect was provided by the extract of S. bracteata, since the minimum inhibitory concentration of this species for S. aureus was equal to 64 µg/ml; and for the other two bacteria, it was equal to 128 µg/ml. The extracts of S. palaestina had the lowest effect on S. aureus and its MIC was observed in a concentration of 1024 µg/ml. The extracts of this species had an MIC equal to 512 µg/ml for the other two bacteria. It was concluded that S. bracreata could be considered a suitable species with anti-bacterial activities in future researches.
 
 
 


Mehrnoush Daneshvar, Mahmood Maleki, Shahryar Shakeri, Amin Baghizadeh,
Volume 6, Issue 4 (1-2020)
Abstract

Phosphorus, the most essential nutrient for plants, becomes quickly unavailable for the plants in the soil. Phosphate solubilizing bacteria (PSB( can play an important role in providing Phosphorus for plants. In this study, the PSBs were screened from plant rhizosphere by Pikovskaya method. Then, the growth rate and phosphate solubilizing ability of 9 superior strains were measured at different temperatures and levels of salinity and pH. The best strain was identified by 16S rDNA gene sequence analysis. Finally, the genetic diversity of phosphate solubilizing strains were examined by RAPD markers. Results showed that 25 strains were capable of solubilizing insoluble phosphates among the 57 isolates studied. Of the nine superior strains, Cke1 had the highest solubilizing index with the average growth rate under all conditions and was introduced as the best PSB strain identified in the present study. 16S rDNA gene sequence analysis showed that this strain belonged to the Enterobacter genus. The results of genetic variation showed that all stains were divided into six groups and three strains that had the lowest similarity with other strains were placed in three separate groups. Given that Cke1 strain has the ability of solubilizing the insoluble phosphate in different stresses, it can be a good candidate for providing phosphorus at temperatures of 30 and 35 °C, 1.2% and 1.8% salinity levels and pH levels of 6 and 8 for the crops.



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