فهرست مطالب احمد علی پوربابایی

Due to the association of some heavy metals with petroleum hydrocarbons, the use of native degrading bacteria of surfactant-producing oil that is resistant to heavy metals is one of the priorities of bioremediation technology. For this purpose, in this study, 39 alkane-degrading and biosurfactant-producing strains were used (isolated from saline soils contaminated with oil in the oil-rich areas of southern Khuzestan province) belonging to the soil microbiology laboratory gene bank of Tehran University. Then, the sensitivity of the isolates to different concentrations (40 to 80 ppm) of heavy metals (chromium, lead, copper, nickel, and cadmium) was tested. The results showed that only three strains Ochrobactrum lupini</em> strain SH23, Ochrobactrum lupini</em> strain SH24, and Bacillus subtilis</em> subsp. Inaquosorum</em> strain SH34 could grow in the presence of all heavy metals. The effects of different concentrations of heavy metals on the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of selected bacteria showed that Ochrobactrum lupini</em> strain SH23 had the highest tolerance to heavy metals. The evaluation of the ability to degrade petroleum hydrocarbons in the presence of heavy metals by selected bacteria showed that the microbial consortium (SH23, SH24, and SH34) and Ochrobactrum lupini</em> strain SH23 were able to degrade 71 and 64% of crude oil with a concentration of 0.5% (v/v), respectively after 10 days of aeration at 30 0C. The findings of this research proved that by conducting additional environmental studies, the bacterium Ochrobactrum lupini</em> strain SH23 can be used in the treatment of water and wastewater contaminated with petroleum hydrocarbons and heavy metals.

Traditionally, most researches on artificial wetlands focuses only on two phases, i.e., water and soil, ignoring or underestimating the importance of the microbial aggregates between them, the third phase in artificial wetlands. Filamentous algae grow substantially by attaching themselves to the soil/sediment surface and form aggregates with bacteria, fungi, and other micro- and meso-organisms (e.g., protozoa and metazoa), known as periphytic biofilms. Actually, periphytic biofilms are ubiquitous in wetlands (including paddy fields) and play a major role in regulating nutrient cycling in these ecosystems. However, their effects on rice plant growth indices have been rarely reported. Therefore, the aim of this study was to investigate the effect of natural periphyton and enriched periphyton with plant growth-promoting microorganisms on germination and rice growth indices.

To achieve the objectives of this study, first three periphyton samples were collected from paddy fields of Guilan province and grown in BG11 medium in the laboratory. Then, the superior bacteria and fungi that stimulated plant growth were isolated from the periphyton mass and the periphyton samples were enriched with these microorganisms. The greenhouse experiment was conducted in 1399 in the research greenhouse of the Department of Soil Science and Engineering, University of Tehran. For this purpose, 2.5 kg pots with a length of 25 cm and a diameter of 15 cm were selected for greenhouse experiments. Twenty rice seeds (Oryza Sativa: cultivar Hashemi) were placed directly in pots in three replications for each treatment. About 100 mL of natural periphyton suspension grown in BG11 medium (equivalent to 2 g/kg dry weight) and periphyton enriched with superior bacteria and fungi and a mixture of bacteria + fungi was added to the pots. Experimental treatments included WP treatment:  without periphyton, PN1 epipelon 13, PN2 epiphyton 8 and PN3 epipelon 6, PN1 + Bacillus cereus, PN2 + Talaromyces stipitatus and PN3 +Acinetobacter calcoaceticus + Talaromyces minioluteus. Also, phosphorus fertilizer treatment at four levels (F0: without phosphorus fertilizer, F1: supply of 50% of phosphorus fertilizer from mono calcium phosphate source, F2: supply of 100% of mono calcium phosphate and F3: supply of 100% of rock phosphate source) was added to the pots. The treatments were grown in three replications in a greenhouse with a temperature between 25–35 °C for 30 days in 80 percent humidity.

The results showed that the presence of natural and enriched periphyton in the soil increased the germination index of rice seeds compared to the control by about 1.4 and 1.9 times, respectively. The rice seedlings decreased by about 10 percent with the presence of natural periphyton, but this negative effect was lowered by enrichment of plant growth promoting microorganisms. Measurement of rice seedling height index showed that the highest measured height was related to the treatment of periphyton enriched with Bacillus cereus (PSB) at F2 level of 39 cm. In general, in natural periphyton treatments, about 15 percent of the height of rice shoots was lower than the control treatment and periphyton treatments enriched with superior microorganisms. The maximum measured root length was related to the treatment of recombinant periphyton with Bacillus cereu (PSB) with 16.95 cm. The lowest root length was measured in natural periphyton treatment (PN3) with 11.5 cm. The highest shoot to root ratio was related to periphyton treatment enriched with Bacillus cereus at F2 and F3 fertilizer levels with 0.7 and 0.68, respectively, with a statistically significant difference at level 95 percentage (p˂ 0.05) compared to other treatments. The maximum weight of rice biomass in periphyton enriched with Bacillus cereus (PSB) treatment, which was the enriched with plant growth promoting bacterium, was measured at F2 and F3 fertilizer levels with 8.7 and 8.3 g, respectively. In general, measurement of rice seedling height, root length, biomass weight and phosphorus in shoots showed that treatment of enriched periphyton with Bacillus cereus at different levels of phosphorus fertilizer had a positive effect and led to an increase of 3.5, 9.4, 6.1, and 35.8 percent compared to the control treatment, respectively.

Finally, it can be concluded that periphyton enriched with superior plant growth microorganisms can be used as a multi-functional biofertilizer in paddy fields, it increases plant growth and efficiency of fertilizer, and it can also control weeds in paddy fields.

Periphyton is a biological layer that is widely present in flood plains such as paddy fields and plays an important role in the nutrient cycle in such ecosystems. The role of this biological layer in dissolving and absorbing insoluble phosphorus in the country's paddy fields has not been recognized so far. This study was performed in the research laboratory of the department of soil science and engineering, university of Tehran in 2020 to investigate the role of periphyton grown in paddy fields of Guilan province in the release and absorption of phosphorus. For this purpose, 20 paddy fields in Guilan province were sampled from epipelon (LON) and epiphyton (TON). The results showed that about 68% of the population of autotrophic components in epipelon and epiphyton samples belonged to Chlorella and Chlorococcum. The genera Lyngbya, Scenedesmus, Nostoc and Navicula were the most abundant in the next ranks. The results of phosphate dissolution showed that samples of LON 6 and 13 and TON 8 have the highest solubility of phosphorus. Phosphorus uptake capacity was also very high in LON 6 and 13 samples and increased by 1840 and 2000% compared to the initial biomass, respectively. This amount was 825 percent in the TON 8. The results also showed that epipelon samples showed a higher ability than epiphyton samples in terms of phosphorus absorption and retention. In general, the results of this study showed that the periphytic biofilm has a high ability to absorb phosphorus, which reduces the waste of fertilizer used and therefore helps to increase its efficiency, and thus reduces non-point pollution.

To date, no research has been done on the role of periphyton in paddy fields, especially on phosphate solubilizing ability of bacteria and fungi isolated from the biofilm. The aim of this study was to investigate the phosphate solubilizing ability and some other plant growth promoting (PGP) traits of bacteria and fungi isolated from the periphyton sampled from 20 paddy fields in Guilan province. In this study, 44 bacterial isolates and 32 fungal isolates capable of solubilizing phosphate were isolated. Among the microbial isolates, effective 10 bacterial isolates and 5 fungal isolates were selected for additional tests. The results showed that bacterial isolates 13B25 and 6B11, with the highest phosphate solubilization, solubilized 354 and 327.3 mg P l-1, respectively. The ability to produce siderophore (based on HD / CD index) by isolate 13B25 and 6B11 was equal to 3.2 and 3.4, respectively, with a significant increase (p < 0.001) compared to other isolates. The production of indole-3-acetic acid by the isolates 13B25 and 6B11 was 175.3 and 205.7 μg ml-1, respectively. Among the fungal isolates, two isolates, 6F11 and 8F12, were the best in PGP traits. The solubilization content of phosphorus by these two fungal isolates was 742 and 818 mg l-1, respectively. The results of molecular identification of effective bacterial isolates showed that 13B25 and 6B11 were most similar to Bacillus cereus and Acinetobacter calcoaceticus, respectively. In addition, fungal isolates 6F9 and 8F12 were most similar to Talaromyces minioluteu and Talaromyces stipitatus, respectively.

Phthalic acid esters are synthetic compounds used as emollients in polymer and plastic compounds. The entry of these compounds into the environment and the human food cycle and the development of a variety of cancers has raised global concerns. The purpose of this research was to investigate the concentration of phthalic acid esters (PAEs) in the soil exposed to the leachate (landfill) and finding a microbial consortium capable of the degradation of these pollutants. The concentration of phthalic acid esters in the soil was measured by the ultrasonic method and GC-MS. The results showed that the concentration of diethyl hexyl phthalate (DEHP) in soil (4.52 mg/Kg) was 6 times that of its international standard (0.7 mg/Kg). Microbial enrichment was performed in a mineral salt medium containing phthalic acid esters (30 o C and 120 rpm) and a microbial consortium capable of degrading phthalic acid esters was isolated. To investigate the biodegradation of phthalic acid esters by consortium, the residual phthalate concentration was extracted with ethyl acetate and measured by GC-MS. The results showed that the this consortium was able to degrade more than 96% of low molecular weight phthalates of dimethyl phthalate, diethyl phthalate and dibutyl phthalate (medium molecular weight phthalate) (30 o C and 120 rpm). In the case of DEHP (the world's most widely used plasticizer), the consortium was able to degrade it by 55% at 400 mg/L. Besides, phthalic acid esters separately were degraded almost completely by this consortium (5 days incubation, 30 oC, 120 rpm). Our results demonstrate the biodegradation of phthalic acid esters by this consortium and recommend its use for bioremediation of phthalates in contaminated soils.

There are hardships in oil-polluted soil remediation that are increased by factors, such as soil salinity and pollution age. This study aimed to evaluate the effect of the native strain of Rhodococcus bacterium and organic waste on the the total petroleum hydrocarbons reduction in contaminated saline soil by crude oil in incubation condition. For this purpose, a full factorial experiment using a completely randomized design was conducted with four factors: bacterial inoculation of Rhodococcus cercidiphylli Y1M65003, 5% spent mushroom compost, 5% sugarcane bagasse, and addition nitrogen and phosphorus with 100: 10: 1 ratio from urea and superphosphate triple. The analysis of variance of total petroleum hydrocarbons elimination showed that all four factors could significantly affect (p

The main objective of this study was to optimize the environmental conditions for maximum growth of Dunaliella salina algae. In this study, effective environmental parameters in algae growth, such as temperature in two levels of 18± °C and 28±2 °C, pH in three levels of 7.0, 7.5, and 8.0 and salinity seven levels of 0.5, 1.0, 1.5, 2.0, 2.5, 3, and 4 molar NaCl in a 30-day culture period were investigated. The dark: light cycle and the constant light intensity were considered 24:0 and 130 130 molPAR. m-2.s-1, respectively. Results depicted that an increase in temperature affecting specific growth rate and a decrease in cell’s population doubling time. The highest specific growth rate and the shortest cell’s doubling time were observed under the condition of pH = 7. Furthermore, the highest specific growth rate was obtained in the salinity of 1.5 molar (0.59 per day) while the lowest specific growth rate in the salinity of 4molar (0.04 per day). The shortest (approximately 1.5 day) and longest (from 10 to 19 days) cell’s doubling time were recorded in salinities of 1.5 and 4molar, respectively, such that by increasing salinity from 0.5 to 1.5 molar, doubling time decreased while by increasing salinity from 1.5 to 4 molar, the doubling time showed a decrease trend. The algae cell concentration increased by an increase in temperature. There were significant differences among cell concentrations in various pH levels. pHs higher and lower than 7.5 led to a decrease in cell concentration. Therefore, in most samples, the maximum cell concentration was observed at pH of 7.5. An increase in temperature when pH was 7.5 let cell concentration to reach its maximum amount faster. By increasing salinity from 0.5 to 1.5 molar, cell concentration increased. In comparison, an adverse effect was observed when salinity increased from 2 to 4 molar. Cell concentration in 1.5 molar salinity condition ranged from  to  and in 4 molar salinity, cell concentration varied from  to . Based on the results of this study, the optimum environmental condition for growth of Dunaliella salina recorded under the salinity = 1.5 molar, temperature = 28±2 °C, and pH = 7.5. Condition of 1and 2 molar salinities with the aforementioned temperature and pH, is suggested as the further option for production of this algae.

Plasticizers are compounds that are widely used to increase the softness of plastic compounds and related derivatives.The largest group of emollients in the world are phthalic acid esters. These compounds consumption is about 10 million tons per year in the world, which covers an annual turnover of $ 20000 million. These compounds are semi-volatile and have carcinogenic, mutagenic, and endocrine-disrupting properties. In this study, phthalic acid ester types and structures, entry paths into different ecosystems and the human body, measurement methods in environmental samples, and studies conducted in the world and Iran are introduced. Due to the weak bond between these compounds and plastics, they can enter the environment and the human food chain easily, and cause many diseases such as breast, thyroid, and testicular cancer, reproductive problems, obesity, asthma, diabetes, and etc. Regarding these properties, the phthalic acid esters are concluded in the list of most dangerous pollutants of the U.S.EPA, China, and the European Union. Unfortunately, very little research has been performed in this field in Iran. Research in the sediments of Anzali wetland, Chabahar Bay water, and the soil downstream Saravan landfill have shown that the concentration of phthalic acid esters, especially diethyl hexyl phthalate (the most widely used plasticizer in the world) has gone beyound the environmental risk limit of these pollutants. It is hoped that the information in this review will help to understand these compounds better and investigating their dangers in Iran environment.

The Bio-Floc has more efficacies compared to fixed Bio-film for removing the nitrogen compounds in water recirculating fish culture system. In this trial, a completely randomized experimental design was run to evaluate the roles of three different ratios of carbon to nitrogen (C:N) including 10 (treatment 10 = T10), 15 (T15) and 20 (T20), into the carp culture systems on growth and water quality. The mean individual weight was significantly higher in T20 compared to the other treatments. At the end of the experiment, the fish attained from 70 to 552.8, 704.7 and 708.8 g in T10, T15 and T20, respectively. The FCR, ammonia and nitrate concentrations were significantly higher in T10 compared to the other treatments (p<0.05). Concentration of ammonia in T10, T15 and T20 were 78, 29.9 and 29.9 mg/L, respectively. A depletion trend was recorded in pH in all treatments during the experimental period. The electrical conductivity (EC) and Bio-Floc formation rate increased in all treatments and was significantly higher in T20. The EC of water were 1327.5, 1419.83 and 1419.83 mmos/cm in T10, T15 and T20, respectively. The rates of Bio-Floc reached to 71, 143, 163 mL/L in T10, T15 and T20, respectively. The results of this experiment indicated that using molasses to adjust C:N ratio of water at 20, enhances formation of Bio-Floc, carp growth rate and water quality in a zero-exchange water system.

Hot spring extreme ecosystems are important biological resources for identifying the genetic stocks of thermophilic microorganisms and their biological characteristics in terms of tolerance and survival in high temperatures in order to use of their potential in various industries and biotechnology. Although there have been many studies on the microbiome of these biomass in recent years in the world, so far few studies have been done on such indigenous extreme environments of Iran. Iran has a variety of geothermal and volcanic areas which contained numerous unique springs with antimicrobial and antifungal, anti-rheumatism and other muscle aches properties. In this study, the identification of composition of different taxa of the bacterial and archaeal community of Ghotoursooyi hot spring as one of the most acidic chloride springs in the world with the pH of 2.87 was performed by independent cultivation methods using next generation sequencing techniques. For quantitative profiling of the relevant microbial community or so-called metagenomics analysis, 16s rRNA gene libraries were constructed from two functional regions of taxonomic classification V4 to V5 and V3 to V4 with barcoded primers for bacteria and archaea, respectivly. Using bioinformatics analysis, 26 and 11 different taxa belonging to different bacterial and archaeal families and genera were identified with MG-RAST systems, respectivly.

Plant growth promoting rhizobacteria with ACC deaminase activity can be applied for stimulating plant growth under tension situations. In the present study, bacterial isolates were isolated from wheat rhizosphere in three provinces of Zanjan, Kurdistan and Hamedan and then screened for ACC deaminase production and salinity tolerance. Six isolates out of 167 isolates were able to degrade ACC to alpha-keto-butyrate and ammonia and the K78 isolate was selected as superior isolate. A completely randomized design with factorial arrangement was carried out on wheat plant in a greenhouse experiment. Experimental factors include: five salinity levels (1.3, 8, 12, 14, and 16 dS.m-1), three bacterial inoculation levels (no inoculation (B0), inoculation with salinity-resistant isolate and ACC deaminase production capacity (B1), inoculation with salinity-resistant isolate without ACC deaminase production capacity (B2). The results showed that salinity had a significant and negative effects on growth and nutrient uptake and decreased shoot length. The K78 isolate increased shoot length (21.5 %) and potassium uptake (15 %) significantly compare to B0 treatment but had no significant effect on sodium uptake. Overall, it can be concluded that inoculation of K78 isolate can reduce the negative effects of salinity on growth indices and the nutritional conditions of wheat.

Actinobacteria efficiently can produce different nanoparticles with various biological properties due to their ability to produce secondary metabolites. The present study aimed to examine the isolation and screening of gold nanoparticles via producing actinobacteria from the soil. We also studied their antibacterial activities.

In this study, after the isolation of actinobacteria, the accumulation of gold nanoparticles was investigated. This aim was achieved by changing the color of the reaction medium and its adsorption by UV-visible spectrophotometry. Then, for conducting confirmatory tests, ultraviolet and visible absorption spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and dynamic light scattering analysis was used. Phenotypic and molecular methods were applied to study the nanoparticle-producing actinobacterium isolate. The antibacterial activity of synthesized gold was explored on pathogenic bacteria.

Among the examined 35 Actinobacteria strains, one strain was biosynthesized nanoparticles; it indicated the maximum absorption at 537 nm, i.e., the characteristic of gold nanoparticles. Dynamic light scattering analysis revealed an average size of 44.4 nm. The minimum inhibitory concentration of gold nanoparticles against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus was 5.8μg/mL, 11.7μg/mL, and 11.7μg/mL, respectively. Molecular analysis data revealed that the Actinobacteria isolate was Amycolatopsis sp. KMN. The isolate Amycolatopsis sp. strain KMN presented 99.82% homology to Amycolatopsis methanolica239.

Overall, according to the obtained results, nanoparticles biosynthesized using Actinobacter cell extract suggested different properties, making them a suitable candidate for further research concerning nanomedicines.

Stresses of drought, salinity and deficiency of nutrients especially phosphorus (P) are the most important challenges for wheat production in Iran. One of the ways to achieve more wheat yield production is increasing of this plants tolerance to stresses of water-deficit, salinity and deficiency of essential elements such as P; and/or alleviate destructive effects of these stresses. In this respect, use of PGPR can be useful. Research has shown that PGPR with multiple mechanisms reduces the negative effects of water-deficit and salinity stresses, and also increases the resistance of plants to these stresses, which ultimately leads to increase of plants growth. This study was designed and carried out to investigate the effect of three superior PGPR on qualitative and quantitative indices of wheat under water-deficit stress in saline soil.

The soil used in this experiment was collected from longitude of 49° 26' 25'' E, latitude of 35° 52' 26'' N and elevation of 1534 m (located in the Qazvin province of Iran) from depth of 0-30 cm of soil. According to the experimental design, 3.5 kg of soil with applying P-fertilizers treatments was filled to the pots. The factorial arrangement based on completely randomized design (CRD) was used in this study. The treatments were replicated three times. The first factor: soil water content at two levels including 80% and 55% FC (W80 and W55); the second factor: Bacterial inoculants at four levels including control or non-inoculated seeds with bacterium (B0), inoculated seeds with Bacillus pumilus strain W72 (B1), inoculated seeds with B. safensis strain W73 (B2), inoculated seeds with Staphylococcus succinus strain R12N2 (B3); and the third factor: P-fertilizers at six levels including control or non-treated plants with P-fertilizers (F0), and plants treated with (rock phosphate) RP - (F1), RP + 19 mg triple superphosphate (TSP) / kg of soil (F2), RP + 38 mg TSP / kg of soil (F3), RP + 57 mg TSP / kg of soil (F4), with 57 mg TSP / kg of soil (F5), generally there were 144 experimental units (pots). Also, 192 mg RP (containing 13.8% P2O5 or 6.13% P) was mixed per kg of soil in each of RP treatments. Statistical analysis of data was performed using SAS software and comparison of means was evaluated by using the Tukey's test (HSD) at p < 0.05 level. There were 5 plants in each pot and irrigated up to 80% FC with distilled water. With the beginning of stem elongation stage, water-deficit stress was applied and continued until the harvest. During the experiment, pots were kept in greenhouse at 25/20±2°C day/night temperatures and 16 h photoperiod with 23,000 lux light intensity. At the end of the experiment, plants height, fertile clusters, root dry weight /shoot dry weight ratio, total dry weight of plant, grain number, thousand grain weight, also, root, shoot and grain P-concentration were measured.

Generally, it can be said that the moisture level of W80 compared to W55 increased all of measured traits in wheat plant. Due to the unique properties of water and its role in biological and non-biological reactions, by reducing soil water content to near of the permanent wilting point (W55), water absorption by the plant hardly occurs. Therefore, the plant needs to consume more energy for water absorption or grow with less water than normal status, which these factors disturb the metabolism of cells and eventually decreases natural activity and growth of plant. Also, it seems that under water stress condition, wheat plant by formation of “Rhizosheaths” around of their own roots, enters to the defensive phase and by this strategy prevents expansion of their own rhizosphere. With attention to the special importance of the rhizosphere in the supply of water, nutrients and activity of microorganisms, as well as the effect of microorganisms secretion and root exudates on the solubility and availability of nutrients. Thus, it is reasonable that qualitative and quantitative traits of plants decrease by reduction of the rhizosphere diameter due to the water-deficit stress. There was no significant difference between application of rock phosphate and control (F0) for most of measured traits of soil and plant; but, application of RP with bacterial treatments (B1 and B2 at W80 and B3 at both level of W55 and W80) compared to the control, often increased measured traits. Also, each level of TSP compared to the control, often increased this trait. Research indicates that RP can be used as a P-fertilizer, but its efficiency depends on its reactivity in the soil. There is ample evidence that RP has not enough efficiency in neutral and alkaline soils; but, it can be used as the P-fertilizer with proper efficiency in acidic soils or alkaline soil with application of PGPR. Often, all of three bacterial treatments (B1, B2 and B3) at level of W80 and B3 treatment at level of W55, compared to control (without bacterial inoculation) improved qualitative and quantitative traits of plant. Research also shows that under stressful and non-stressful conditions, PGPR can improve plant growth by different strategies. However, this microorganism does not always improve plant growth under all conditions. It seems to be due to differences in genetic and function of bacteria and with conditions change, each bacterium may behave differently. Conclusions In general, for wheat cultivation that may get exposed to moisture stress at one or more stages of its growth (such as dry-farming of wheat), the use of B3 bacterial inoculant (Staphylococcus succinus strain R12N2) seems appropriate for crop management. Because in this study at both W80 (non-water-deficit stress) and W55 (severe water-deficit stress) levels of soil water content, B3 treatment increased qualitative and quantitative of wheat traits. In other words, because of the natural conditions of the dryland farming, the probability of precipitation is different; it seems that B3 treatment can increase wheat production under these conditions. However, the use of this bacterium as a biofertilizer for dryland wheat farming in Iran or other place of the world requires further testing and evaluation in dryland farms of that countries.

Currently, the excessive application of chemical fertilizers in agriculture field is under debate due to environmental concerns. Therefore, it is important to find the alternative strategies to reduce harmful effects of farming practices. Aims of the research was to investigate the potential of rhizosphere and endophytic bacterial isolates isolated from the roots of wheat plant in terms of plant growth promoting (PGP) traits and study their effect on the wheat plant growth indices and decreased phosphorus (P) fertilizer use. To this end, the isolated bacteria were first screened for the production of indole-3-acetic acid (IAA) in the presence of tryptophan in the culture medium, and then the bacteria were tested for their ability to dissolve inorganic and organic phosphates. Then, the ability of these bacteria to improve wheat plant growth was conducted in a completely randomized design under greenhouse condition. Rhizospheric isolate R185 and endophyte isolate E240 produced 299.2 and 330.1 μg / ml P respectively and also produced 19.2 and 22 μg / ml IAA, respectively. 16S rRNA sequencing showed that these bacterial isolates were Pseudomonas. The results obtained from pot assay showed that the combined use of the strains caused a significant increase in wheat growth and nutritional indices (an increase of 55.6% in the amount of plant P) compared to their single application (35.6 and 36.4% increase in plant P content by R185 and E240, respectively). Among the cultivars evaluated, Roshan cultivar had a higher percentage of P (4.7%) and biomass (14.2%) than Marvdasht cultivar.

Despite the abundance of iron in the earth's crust and soil, this nutrient is not usually available for plants in calcareous soil with high pH. In the present study four superior isolates with alternative physiological traits (No. 3, 8, 20 and 23) isolated from 10 soil samples for producing siderophore and their contribution in solubilizing insoluble iron-containing compounds in calcareous soil were evaluated. Results showed that in spite of higher halo diameter to colony diameter of isolate No. 23 in CAS agar medium (3.46mm) at soil incubation test, DTPA-extractable iron using isolates No. 3 and 20 was greater than the ones in isolate No. 23 as 10.7 and 14.67 percent, respectively. Greatest amount of DTPA-extractable iron in the soil sample was obtained during 40-days incubation. Molecular test showed that isolate 20 was 99 percent similar to the strain Bacillus Sporothernodurans. Biochemical tests also revealed that isolate 8 probably belong to Entrobacteriaceae family and isolates 3 and 23 belong to Pseudomonas Genus.

Food packaging as a protective layer is one of the most important factors that play a key role in providing healthy food. The aim of this study was to provide a novel paper packaging material by coating with a new dispersion barrier coating based on a mixture of soy protein isolate (SPI) and polyethylene wax (PE-wax) emulsion. For this purpose, mechanical properties, water absorption resistance and oxygen permeability of the specimens were investigated. The results indicated that although the tensile strength of coated paperboards decreased with the addition of PE-wax, there was no significant difference between the SPI-coated paperboards and 30% PE-wax coated ones, and 50% PE-wax coated paperboards showed only a decrease of 6% compared to SPI-coated ones. With increasing the share of PE-wax in the coating formulation, oxygen permeability increased in the coated paperboards but water absorption and water vapor permeability decreased dramatically.

Drought, salinity and essential plant nutrient stresses especially phosphorus (P) are the most important challenges for wheat production in dryland farming of Iran. The objective of this study was to investigate the effect of three plant growth promoting bacteria strains on soil available-P, as well as some of the physiological and growth traits of wheat under water-deficit stress. For this purpose, a pot experiment was carried out as factorial arrangement with three factors including: water deficit stress at two levels, application of P-fertilizer at six levels and strains of plant growth promoting bacteria at four levels, based on completely randomized design (CRD) with three replications within 125 days. The results show at the water deficit stress of 55% field capacity (FC) and without P-fertilizer application, bacterial treatment of Staphylococcus succinus compared to control increased available-P, P-uptake of root and grain by 2.4, 4.9 and 2.7 times respectively. At moisture treatment of 80% FC and without P-fertilizer application, treatments of Bacillus pumilus, B.safensis and S. succinus compared to control, increased available-P by 1.6, 1.6 and 1.6 times; P-uptake of root by 3.1, 3.1 and 2.9 times; P-uptake of grain by 2.2, 2.4 and 2.2 times, respectively. Maximum dry weight of root, shoot and grain (5.3, 18.2 and 4.6 g pot-1, respectively) were obtained at the maximum level of P-fertilizer treatment (F4). At the water deficit stress of 55% FC, bacterial treatment of S. succinus compared to control increased prolin, root dry weight, grain dry weight and P-uptake of shoot up to 8, 31.9, 20.4 and 25.5 percent, respectively. Generally, the use of Staphylococcus succinus strain R12N2 seems to be appropriate for increasing wheat production in dryland farming.

Peroxidases are used in a wide range of biotechnological processes, most of which are carried out at high temperatures and high pH levels. Since most of the commonly used peroxidases are unstable and inactive in alkaline conditions and high temprature, it is necessary to find thermoalkalophilic peroxidases for practical purposes.

In this study, extracellular production of peroxidase in the native strain Bacillus tequilensis was studied. for this purpose, Enzyme activity was evaluated using two substrates 2,4-DCP and pyrogallol in bacterial liquid culture and the effect of culture time on enzyme production, as well as the effect of parameters such as pH and temperature on enzyme activity investigated. The relative purification of the enzyme was performed using ion exchange chromatography with sephadex DEAE A50 and the kinetic parameters of enzyme activity were evaluated. In this study, kinetic parameters such as Km and Vmax were calculated.

Measurement of enzyme activity at different times of culture indicated that the highest amount of peroxidase production was obtained 72 h after bacterial culture.

Introduction :

The use of invitro hydroponic culture is one of the useful and practical methods for selection of superior isolates of plant growth promoting rhizobacteria with high colonization potential at root surface. In this regard, the present study was designed to select superior isolates isolated from dry-land farming of Qazvin and Zanjan provinces during the previous stages of this investigation.

Materials and Methods:

 This experiment was carried out based on a completely randomized design (CRD), including: inoculation of wheat seeds with 16 bacterial isolates and culture of seedlings in Hoagland nutrient solution (EC 8 dS/m and osmotic potential (OP) -0.54 MPa) containing tricalcium phosphate (source of low-soluble phosphorus), as well as non-inoculated seedlings was cultured in Hoagland nutrient solutions containing monopotassium phosphate (control with source of soluble phosphorus) and tricalcium phosphate (control with source of low-soluble phosphorus) at three replications in growth chamber for 45 days. The length of the light (with 196 μmol photons m−2 s-1 light intensity) and dark period in these times was 16 and 8 h, respectively, The day and night temperature were 25±2 and 20±2 °C, respectively. At end of experiment (45 days after transportation of seedlings into invitro hydroponic culture) shoots and roots of plants were harvested separately; then, Population of phosphate solubilizing bacteria (PSB) on root surface, pH and concentration of available phosphorus in nutrient solution, fresh weight, dry weight and length of both section of plants, P-concentration and P-uptake of plant, and relative water content (RWC) of leaf were measured. Ultimately, correlation (Pearson) among measured traits were calculated.

Results and Discussion:

 Results showed that inoculated wheat seedlings with B18 isolate perished. It seems that B18 isolate was either a highly pathogenic plant or its metabolites were highly inhibitory to the seedling which in short time killed the wheat seedling. Except B (14, 17, and 32) isolates; the rest of isolates had over 6×106 CFU/g root fresh weight. All bacterial isolates compared to the control with source of insoluble phosphorus, increased available phosphorus and decreased pH of nutrient solution. Dissolution of inorganic phosphates by PSB with chelating processes, secretion of inorganic and organic acids has been proven topic. Thus, reducing pH and increasing soluble phosphorus in nutrient solution at PSB treatments are reasonable. B (1, 2, 3, 4, 5, 6, 14, 17, 32) isolates treatments compared to control with tricalcium phosphate, increased RWC of leaf, and also increased length, fresh weight and dry weight of root and shoot of wheat plants. Previous research has shown that inoculation of plants with PGPR under drought and salinity conditions improved RWC of plant leaves and plant growth indices; Of course, result of some experiment show that some of PGPR do not always improve plant growth under all conditions. There was a significant positive correlation among P-uptake, RWC, root length, shoot height, fresh and dry weight of root and shoot of wheat plant. Also, the pH of nutrient solution had a positive correlation with root length, but it had a negative and significant correlation with P-concentration of nutrient solution and P-concentration of plant. PSB population at root surface had a negative correlation with pH of nutrient solution and root length of plant, but with P-concentration of nutrient solution had positive and significant correlation.

Conclusion:

 All of screened and selected PSB isolates in lab (in respect of PGP traits) could not promote plant growth; even some of these isolates (such as B15 and B18) had negative effects on wheat growth indices. Inoculation of wheat with PSB isolates significantly increased the use of insoluble phosphorus. Solubility of tricalcium phosphate by isolates and increased phosphorus availability cannot lonely improve wheat growth indices; it seems that the outcome of the set of PGP effects of these bacteria and the secretion of their metabolites in the presence of plant root are determinative agents for improvement of wheat growth indices. Generally, B (1, 2, 3, 4, 5, 6, and 32) isolates were superior isolates in respect of colonization at root surface, relative water content (RWC) and growth indices of wheat plant; and these isolates are recommended for further experiments in greenhouse and field (in order to production of suitable biofertilizer for dry-land farming of wheat).

Luteolin is one of the most important flavonoids, which release from seeds during the first four hours of imbibition. On the other hand, at present, salinity is one of the most important factors in reducing crop production. The results of some studies show that the use of external flavonoids increases expression of nod genes, yield and nodulation in some legumes species under stress conditions. Therefore, this experiment was conducted with the aim of investigating the effect of luteolin and alfalfa seed exudates external inducers on the expression of Rhizobium nod gene and the yield and nodulation of alfalfa in normal and salinity condition.

We studied the effect of luteolin on the induction of nod genes in R. Meliloti carrying a plasmid with a translational fusion between R. Meliloti nodA and lacZ of Escherichia coli, and the expression activity was measured by β-galactosidase activity. Luteolin strongly induced the expression of nod genes inhibitory effects. We further studied the effect of luteolin and Seed exudate on alfalfa (Medicago sativa L.) yield and nodulation under optimal and salinity condition. One greenhouse was conducted to determine whether the pre-incubation of Rhizobium meliloti with luteolin and application of luteolin and seed exudate directly on to the seed surface can increase alfalfa nodulation and yield. The factorial experiment was arranged based on randomized complete block design, with three replications. Treatments were two cultivars, two bacterial strains (Sensitive and resistant strains), two levels of salt (0 and 15 dS.m-1 of NaCl) and two levels of application of inducers along with control.

The results from this experiment clearly indicated that inoculation of alfalfa seeds with luteolin and seed exudate increase alfalfa nodulation (47%) and yield (30%) significantly under salinity condition that these treats affect on traits more under normal condition. But significant effect was not observed on chlorophyll content. In this experiment a significant difference was not observed between the control and pre-incubation of R. meliloti. Also, salinity increased proline four times compared to normal condition. Luteolin and seed exudates increased proline 1.66 and 1.35 times respectively in salinity condition, but under normal condition they did not have significant effect. Salinity increased the content of sodium in the leaves (7 times) and roots (8.5 times) and decreased the content of potassium 29% and 24% in these organs of the plant, respectively, that, luteolin and seed exudate partially moderated these changes.

The results of this experiment indicated that luteolin and seed exudate can be used as exogenous inducers to improve the growth and nodulation of alfalfa under salinity and normal condition. Flavonoid inducers act in low concentration, and their negative effects relate to reduced germination and growth. In general, it seems that the application of flavonoid inducers is more suitable to improve nodulation, but the direct application of them in agriculture should be used only in specified cases and when flavonoids are as a limiting factor.

Cellulolytic bacteria with cellulase enzyme system play an important role in decomposing lignocellulose wastes and accelerating the composting process. For this purpose, a study was carried out on some native cellulolytic bacteria isolated from different sources in Soil and Water Research Institute. Twenty eight isolates were selected based on morphological characteristics and cellololytic test, in specific medium (B.H.M). Spot cultivation on B.H.M medium and observation of halo diameter as the cellulolytic characteristics of the isolates led to the separation of 12 isolates. The maximum and minimum diameter of a clear zone around the colony of MAL and HSE isolates were 31 and 8 millimeters respectively. Also the maximum and minimum proportion of clear zone diameter to colony were observed in TER and CPL isolates. The activity of endoglucanase, exoglucanase and betaglucosaidase among 12 isolates showed that the least amount of endoglucanase was belong to SAD (0.17 U.ml-1) and the most one was NTL (2.55 U.ml-1) isolates. The maximum activity of betaglucosidase in NTT isolate was 0.31 U.ml-1 and the maximum exoglucanase enzyme activity was belong to HPN isolate (0.35 U.ml-1)and minimum was belong to BSB isolate (0.18 U.ml-1). Analysis of variance showed that the differences between the isolates with the highest and lowest triple cellulase activity was significant (especially endoglucanase (at one percent statistic level but was not significant between some isolates. There was a direct relation between cellulase activity and the enzyme compound. NTT isolate showed the highest activity of beta-glucosidase enzymes and it was the second and the third in terms of endoglucanase and exoglucanase production, respectively. It had the highest activity of three enzymes (3.21 unit) and identified and registered as Bacillus methyltrophicus.

To increase the symbioticnitrogen fixation in soybean, a native Bradyrhizobium japonicum strain RS 117 was selected from four strains via infectiveness, symbiotic effectiveness and sequancing 16S rRNA gene. Then, mentioned strain in the form of YMB inoculum wasirradiated by gamma rays dosages 0-5000 Gray with a 500 Gray interval dosage. About 800 mutant isolates were collected on YMA from different doses. 11 isolates in efficiency point of view changing the GMGT media colour were selected as the best isolates for further study. These isolates were tested for their symbiotic effectiveness (SE) under proper greenhouse condition with a randomized complete block design in 3 replications; and 3 more efficient isolates No. 3, 8 and 9  increased 56- 81 percent SE more than wild strain. At last, relative gene expersion nodA, nifK2 in mutant and wild strain bacteria approved mollacular differences between both of them by indicating Increase and decrease in amount, in mutant isolate number 9 in comparison with the wild Bradyrhizobium japonicum strain RS 117. The results indicate that gamma-irradiated mutations in Bradyrhizobium japonicum strains have significantly increased the biological fixation of nitrogen in soybean plants.

Lack of oxygen and high salinity are factors that limit the biodegradation of the hydrocarbon. The electron accepters such as nitrate and salt tolerant bacteria can be used to increase the biodegradation rate in saline environment with low level of oxygen. In this paper, BTEX biodegradation by Bacillus thuringiensis andBacillus sp. is investigated in microaerophilic and saline environment under nitrate reducing condition. Firstly, the ability of the above- mentioned bacteria in BTEX biodegradation was confirmed. Then, the effect of Nitrate, BTEX concentration, salinity and cell mass on BTEX degradation was studied using Taguchi method and design expert software. The results of this study showed the ability of the Bacillus thuringiensis andBacillus sp. on BTEX degradation. For 200 mg/L BTEX concentration, the high efficiency of degradation by Bacillus thuringiensis andBacillus sp. could be achieved in optimum conditions; Nitrate Concentration (200 mg/L), salinity (1 and 5 %) and cell mass (1and 5×107 cell/ml) respectively.

Despite of numerous studies on BTEX biodegradation, a few researches has been conducted to optimize the environmental conditions for biodegradation of this pollutant considering the effective factors. The objective of this study was to investigate the effect of environmental factors such as nitrate, salinity and cell mass (the isolated bacterium from the soil) on BTEX degradation and to optimize the environmental conditions for biodegradation. In order to identify the appropriate microorganism for BTEX degradation, isolation of the bacterium from the oil contaminated soil was performed firstly. Then the nitrate, salinity, cell mass and BTEX concentrations were considered as independent variables to optimize BTEX degradation conditions by the isolated bacterium. Finally, a quadratic polynomial mathematical model was suggested by the Design Expert software (R2=0.85). This research showed that the isolated bacterium is able to degrade BTEX and the proper condition for degradation can be achieved by applying the above-mentioned model. Results showed that the effect of BTEX and Nitrate concentration on BTEX degradation is significant. So that increasing BTEX concentration to the extent of 200 ppm and decreasing nitrate concentration to the extent of 400 ppm reduced BTEX degradation to 4.2% and 9%, respectively.