ali akbar safari sinegani

The purpose of the present study was to investigate the antibiotic resistance of culturable bacteria following the increase of three commonly used antibiotics in three agricultural, rangeland, and mine soils with different amounts of heavy metals. Antibiotics amoxicillin, cefixime, and metronidazole were used in amounts of 100 and 200 mg per kilogram of agricultural, rangeland, and mine soils. Then, in a short time incubation (zero, 1, 3, and 7 days), the abundance of bacteria in nutrient agar medium and the percentage of resistant bacteria in nutrient agar medium with antibiotics (16 µg of amoxicillin, 2 µg of cefixime, 8 µg of gentamicin, 16 µg of metronidazole and 8 µg of tetracycline per milliliter of nutrient agar) were counted and estimated. The percentage of bacteria resistant to cefixime, gentamicin, and tetracycline in mine soil, especially rangeland soil, which had high contamination with heavy metals, was higher than in agricultural soil, and only the percentage of bacteria resistant to amoxicillin and metronidazole was higher in agricultural soil than mine soil. In rangeland soil, 100% of bacteria were resistant to the tested antibiotics except for tetracycline. Treatment of soils with amoxicillin caused an increase in the number of resistant bacteria, which was especially evident in agricultural soils at a concentration of 200 mg.kg-1. The same finding was also seen in the application of cefixime, but in mine soil, the high concentration of this antibiotic showed a decrease, and the percentage of resistant bacteria in both rangeland and agricultural soils was close to 100%, but in mine soil, it reached less than 20%. There was a significant increase in the number of resistant bacteria in the soils treated with metronidazole compared to control soils. But, in this treatment, the response of agricultural soil bacteria to a concentration of 200 mg.kg-1 was decreased, and mine soil did not show such a response. In all treatments, the bactericidal power of tetracycline and then gentamicin in the concentrations used in the culture medium was higher compared to the three antibiotics of amoxicillin, cefixime, and metronidazole. Antibiotic resistance of soil bacteria is dependent on soil contamination with heavy metals and diversity of soil bacteria, genetic pool, and ability to move resistance genes between them. The increase of antibiotics in the soil, depending on the characteristics of the soil and the antibiotic causes the dominance of special and resistant species, which increases the transfer of resistance genes and their abundance in the environment.

Municipal and hospital waste land fills that have various contaminants, especially pharmaceuticals, provide a suitable habitat for resistant bacteria which play a special role in the transfer of resistance genes. Therefore, the abundance of microorganisms and the antibiotic resistance of bacteria in soil and leachate samples of municipal and hospital waste burial sites in Hamedan city were investigated.

The characteristics of soil and leachate as well as the abundance of their microorganisms were tested and counted. Also, the percentage of bacteria resistant to ten commonly used antibiotics ampicillin, amoxicillin, cefixime, gentamicin, streptomycin, tetracycline, doxycycline, chloramphenicol, lincomycin and metronidazole was investigated. In addition, the response of bacteria from two virgin soils and new rubbish landfill to different concentrations of three antibiotics, ampicillin, gentamicin and tetracycline, were measured.

The log of population of fungi, actinomycetes, pseudomonas, and enterobacters, was the highest in new rubbish landfill. They were 5.35, 5.28, 6.13, and 5.98 respectively. The percentage of bacteria resistant to all ten antibiotics was higher in samples of new rubbish landfill than in other locations and lower in virgin soil than in other locations. These results were also seen in the dose response of ampicillin, gentamicin and tetracycline antibiotics. The inhibitory concentrations of these antibiotics for new rubbish landfill bacteria were 1500, 1000 and 100 mg/l, respectively. But for virgin soil, they were much less (10, 18 and 50 mg/l respectively).

In general, this research showed that municipal and hospital waste landfills provide a suitable habitat for antibiotic-resistant bacteria, which may increase the transfer of resistant genes among soil native bacteria. Therefore, the bacteria that reach the soil through waste can be more harmful.

The biological pollution of landfill sites for urban waste is a crucial concern. This study aims to investigate the resistance of bacteria in contaminated soils at waste burial sites against heavy metals in Hamadan.

The physical and chemical characteristics of soils were examined, and the total amounts of metals such as copper, lead, zinc, and cadmium were measured. Additionally, pollution load index (PLI), average pollution index (PIavg), and pollution degree (Cdeg) were estimated and analyzed. Furthermore, the percentage of stable bacteria resistant to copper, lead, cadmium, and zinc in the NA culture medium was studied by measuring the logarithm of microorganism abundance

Among the mentioned sites, the soil surrounding the leachate lagoon exhibited the highest levels of organic carbon, available phosphorus, and potassium. The PLI and PIavg indices for virgin soil were below one, indicating that this soil was not polluted. However, these indices were above one for the other five sites, indicating pollution. The intensity of soil pollution in these sites exceeded the permissible limit. The logarithm of population for fungi, actinomycetes, pseudomonas, and enterobacters was highest in the new rubbish landfill, with values of 5.35, 5.28, 6.13, and 5.98, respectively. The percentage of bacteria resistant to lead was 100% in all sampled soils, but in the leachate, it was lower than 64%.

Overall, the percentages of bacteria resistant to copper, zinc, and cadmium in the new rubbish landfill site were higher compared to other sites, which may be attributed to the landfilling of urban waste in the soil.

This study aimed to investigate the effect of Amoxicillin, Cefixime, and Metronidazole on some biological properties such as basal respiration, substrate-induced respiration, and bacterial abundance in uncontaminated and heavy metal-contaminated soils. The experiment has performed with a completely randomized factorial design with three replications. Factors include three soil types (heavy metal contaminated mine soil, rangeland soil near mine, and agricultural soil), seven antibiotic treatments (control, Amoxicillin, Cefixime, and Metronidazole, each one 100 and 200 mg per kg of dry soil) and three incubation times: short-time (zero-7 days), medium-time (15 and 30 days) and long-time (60 and 90 days)). The results showed that in the medium time, the application of 200 mg.kg-1 of antibiotics amoxicillin in agricultural soil and metronidazole in mine soil, resulted in the highest (8.4958) and lowest (4.4594) logarithm of the abundance of all soil bacteria. Rangeland soil had the highest basal respiration amount (0.1066 mg CO2. g-1dry soil. day-1) in short-time incubation, and agricultural soil had the lowest basal respiration amount in both long-time (0.0144) and medium-time (0.0172). The use of 100 mg of metronidazole per kg of rangeland soil in the short time resulted in the highest amount of substrate-induced respiration (0.0251 mg CO2. g-1 dry soil. h-1) and the use of 100 mg of amoxicillin per kg of agricultural soil in the medium incubation time resulted in the lowest substrate-induced respiration (0.0027). It seems that agricultural soil showed the highest abundance of bacteria and mine soil showed the highest amount of substrate-induced respiration. Rangeland soil had the highest amount of basal respiration and there was no significant difference with agricultural soil in the abundance of bacteria and mine soil in the amount of substrate induced respiration. Mine soil showed the lowest abundance of bacteria and agricultural soil showed the lowest amount of basal and substrate induced respiration. The application of metronidazole resulted in the highest amount of basal and substrate induced respiration, and the lowest abundance of bacteria. The application of amoxicillin and Cefixime showed the highest abundance of bacteria and the lowest amount of substrate induced respiration, respectively. Incubation in a short time had the highest amount of basal and substrate induced respiration. The highest abundance of bacteria and the lowest amount of substrate induced respiration were observed in the medium time. The long-time incubation showed the lowest abundance of bacteria and the lowest basal respiration amount.

The maintenance of planted forests in arid and semi-arid lands is important. Soil formation in forest ecosystems is different with different tree species. Tree species have a direct and indirect effect on soil organisms. Forest ecosystems change their species composition and abundance of microorganisms, and consequently their biogeochemical cycles. The accumulation of vegetation biomass and the improvement of soil fertility can play a significant role in soil restoration.

In order to investigate the biological characteristics of the soil from 5 treatments, including agricultural (dry farming and relatively poor lands that are usually cultivated barley and wheat and have low productivity), pasture (pastures with minimal vegetation and high slopes that are affected by overgrazing have been changed to barren lands), forest with Acacia type (under and outside the crown), forest with the Cupressus arizonica type (under and outside the crown) and forest with the Pinus brutia type (under and outside the crown) randomly. Sampling was done in 3 repetitions from the 0 to 5 cm layer. The statistical sampling design of this research was completely random, in which, according to the type of afforested species, two types of coniferous forest stands (including Cupressus arizonica and Pinus brutia) and one broadleaf stand (Acacia species) were selected. Also, the area under the crown trees and outside the crown trees was also investigated. Soil samples were sampled with sterile equipment and crushed through a 4-mm sieve. Fresh and moist soil was kept at 4 °C temperature for soil biological tests. Microbial biomass carbon, soil basal respiration (197 days), substrate-induced respiration, and metabolic quotient were measured. Streptomycin sulfate was used to measure fungal respiration and cycloheximide was used to measure bacterial respiration. The activities of urease, acid, and alkaline phosphatase enzymes were determined. After measuring the biological properties of the soil, the normality of the data was checked by the Anderson–Darling test, and the homogeneity of the variance of the treatments was checked by using Levene's test. Analysis of data variance was done using One-Way ANOVA and average data comparison was done using Duncan's test at 5 and 1% probability levels (SAS 9.4 and SPSS 26).

The results of soil biological characteristics analysis showed that the highest values of soil respiration and amount of consumed organic matter, substrate-induced respiration, microbial biomass carbon, enzyme activities, and fungal respiration were measured in conifers. Although the amount of these features was also significant in broadleaf trees, they had significant differences. In this study, the high soil respiration rate in coniferous covers compared to broadleaf can be due to the high organic carbon content of the soil in this cover. According to the results of substrate-induced respiration in different coatings, likely the activity of microorganisms involved in the decomposition of organic matter in the studied habitats had a significant difference; Therefore, different coatings can affect the population of soil microorganisms as the main source of decomposition and emission of carbon dioxide by changing the quantity and quality of organic matter and other factors. Also, the highest values of metabolic quotient and bacterial respiration were observed in agricultural and pasture covers. A higher metabolic quotient in these covers indicates a decrease in the efficiency of the use of leaf litter by the soil microbial community. In general, the metabolic quotient in the bacterial community is higher than the fungal community; Therefore, it seems that the predominance of the bacterial population in agricultural and pasture cover has caused this index to increase, although plowing and cultivation, and disturbance of these covers have caused stress to this bacterial community and as a result increased the metabolic quotient deficit in these covers.

The results of this research showed that the type of planted tree species causes significant changes in the biological characteristics of the soil. The current research shows that the forest, whether coniferous or broadleaf, had the highest values of enzyme activities, basal respiration, substrate-induced respiration, microbial biomass carbon, and the lowest values of metabolic quotient compared to agricultural and pasture covers. Afforestation increases biological activity and possibly the number and diversity of microorganisms, and improves soil characteristics in the long term. In agriculture and pasture land, due to the destruction of soil and aggregates by agricultural activities such as plowing or excessive livestock grazing, the amount of organic carbon and the activity of microorganisms decreases, and with the decrease of other soil characteristics, the quality of the soil decreases over time. From this research, it can be concluded that the planting of forest species in the soils of degraded areas in the long term can increase soil organic carbon due to high-quality leaf litter, and as a result, increase permeability and soil moisture. Increasing soil organic carbon increases the activity of microorganisms, and in the long term, it will improve various soil characteristics. Planting forest plants in the natural areas of the country, which were destroyed due to the change of use to agriculture and indiscriminate cultivation and finally abandoned, can improve the characteristics of the soil and, as a result, establish the native vegetation of the region, and increase the permeability of water in the soil, the risk of soil erosion, floods, etc. reduce.

The purpose was to specify the impacts of amoxicillin, cefixime, and metronidazole on sunray cultivar of green bean (Phaseolus vulgaris L .) growth and some of its metabolites, which were cultured in soils with various quantities of heavy metals.

For evaluation of the effects of the antibiotics (i.e., Amoxicillin, Cefixime, and Metronidazole) on plant growth, the Antibiotics were tested in 2 doses of 100 and 200 mg.kg-1 soil, and zero for the control. After 42 days fresh and dry weights of green bean shoots and roots were analyzed, and before harvesting the quantity of Chlorophyll (Chl) a, Chl b, Carotenoid (Car), Flavonoids, Phenol, and Antioxidant activity in P. vulgaris leaves were measured.

Green bean treated with Amoxicillin (200 mg.kg-1) produced the highest root dry weight in mine soil (42.91% increase compared to control) while it treated with cefixime (200 mg.kg-1) produced the highest shoot dry weight at rangeland soil (19.21% increase compared to control). The quantity of Flavonoids (18.91%), Phenol (19.70%), Chl a (37.72%), and total Chl (37.40%) in the leaves of the plant with 200 mg.kg-1 Metronidazole reduced in compared to their controls. The results showed that antioxidant activity in green bean tissues was enhanced in mine soil compared to agricultural and rangeland soils (37.76% and 18.43% respectively).

Though soil contamination with heavy metals and the usage of metronidazole had stressful results on green beans, these were not additive or synergetic. Residues of Antibiotics often enter agricultural soils through animal manure, so it is suggested to use at least decomposed manure to control their stressful effects and the arrival of Antibiotics into the food chain.

A study was conducted as split plot layout with three replications at the research greenhouse of Bu-Ali Sina University, Hamedan in 2017 in order to investigate the consequences of using biochar and hydrochar, produced from potato plant residue on bean plant growth indices, chlorophyll content, and root mycorrhizal symbiosis in drought stress. The main plot and subplots in this study have been two drought levels and four amendment treatments, respectively. The study shows that the drought stress and the application amendments in various forms have had significant effects on plant growth indices, chlorophyll content, and root mycorrhizal colonization. Drought stress reduces root and shoot dry weights up to 39.8, 46.1%, leaf chlorophyll a (Chl a) content up to 52.6%, chlorophyll b (Chl b) content up to 58%, and total chlorophyll up to 54.52%. Although the number of rhizobium nodule on the root of plant decreases in drought stress, the rate of root mycorrhiza rises by 19.2% in drought stress. The use of biochar increased the mycorrhizal symbiotic indices significantly. It increases root colonization 11.34% and Glomeromycota spore number 50.5% in soil. The application of raw residue in soil has had the most positive effects on the plant growth indices and the leaf chlorophyll contents, leading to increased shoot dry weights (49.8%) and chlorophyll a, b and total contents (3.54%, 36.8%, and 14.5% respectively). The findings of this study show that among the treatments, the best plant growth index has been obtained in the use of potato biochar, which reduces the harmful effects of drought stress on the bean plant.

Potato is the fifth agricultural crop in the world that is an origin of carbohydrates, proteins and essential amino acids for humans. Agricultural inputs have special performance in increasing the quality and quantity of potatoes. But, the excessive use of chemical fertilizers sometimes leads to many health and biological problems. Useful soil microorganisms can have special efficiency in improving plant growth, harvesting agricultural products and subsequently reducing its costs. In addition to physical and chemical properties, soil condition is closely related to its biological properties. The aim of this study was to investigate the application of 10 strains of potassium, phosphorus and iron solubilizing bacteria on the growth parameters of Geely potato cultivar and to produce Geely’s healthier product.

The research was done in the greenhouse of Hamadan Agricultural Research Center in 1398. It was conducted in a completely randomized design with three replications. The treatments included 10 identified potassium, phosphorus and iron solubilizing bacteria, 1 Potabarvar biofertilizer and 1 control treatment (without any biofertilizer and bacteria). The measured traits were tuber wet weight, number of tubers, biological production, plant height, root dry weight, shoot dry weight, dry matter percentage, concentrations of phosphorus, potassium, iron and zinc in roots, shoots, tubers and soil.

The results showed that the application of potassium, phosphorus and iron solubilizing bacteria increased the growth parameters of the potato plants, the uptake of phosphorus, potassium, iron and zinc by potatoes significantly. The most efficient bacterium in this study was Pseudomonas frederiksbergensis that was more potent than other bacteria for most plant growth parameters and nutrient uptake . For this treatment, root dry weight was obtained 17.66 g/pot, which was 103.92% higher than the control. By the treatment with this bacterium, the maximum shoot dry weight was 47 g/pot which was 88% higher than the control. The concentrations of zinc in roots, and phosphorus, potassium, iron and zinc in shoots, that were obtained from inoculation with Pseudomonas frederiksbergensis, were 0.034, 6.666, 333.16, 460, 0.041, 3.86, 24.20 mg/kg, respectively; These values showed significant differences with the control and other treatments. In this study, Enterobacter ludwigii and Brevundimonas vesicularis were the most inefficient bacteria.

The results of the study showed that application of potassium solubilizing bacteria as biofertilizers can improve plant growth and increase its performance. It can be said that the use of biofertilizers along with chemical fertilizers might be helpful to reduce environmental pollution and to decrease costs.

Phosphorus is the most widely used element for plant growth and development after nitrogen. Although the phosphorus content is high in soils, its bioavailability for plants is very low. Therefore, using biological methods to increase its bioavailability is very beneficial. In this study, 15 isolates of plant endophytic mycorrhiza-like fungi were used to increase phosphorus bioavailability in two soil phosphorite (5 g.L-1) modified Pikovskaya culture media with two concentrations of organic carbon (1% and 7% glucose) in three replications and sampled in four times. Analysis of the data showed that the release of phosphorus and calcium was associated with the reduction in pH of culture media. All fungi have the ability to release phosphorus and the ability of fungi was significantly higher in the 7% glucose concentration. The highest amount of solubilized phosphorus was obtained with inoculation of Aspergillus terreus, Aspergillus calidoustus, and Alternaria botrytis in the modified Pikovskaya culture medium with 7% glucose. The solubilized P concentration in 30th day of incubation was equal to 339.56, 334.19 and 334.64 mg L-1 respectively. Also, the highest amount of the dissolved calcium in the medium with 7% glucose in Aspergillus terreus and Aspergillus calidoustus treatments was 423.36 and 403.36 mg L-1 respectively. However, the highest electrical conductivity in the medium with 7% glucose was obtained in the cultivation of Alternaria botrytis, which was equal to 3.01 dS m-1 in 30th day of incubation. The amount of the dissolved calcium and the electrical conductivity increased continuously over a period of time for thirty days. This may dependent on the pH reduction and mineral P solubilization by fungi. The analysis of biomass P in fungal hyphae showed that the fungi with lower ability in P release in solution had higher biomass P. The highest pH and biomass P was measured in the Penicilium sp. culture medium with the lowest EC and solubilized Ca. The lowest amount biomass P in 7% glucose in Alternaria botrytis, Giberlla thapsina and Alternaria consortialis treatments. This study revealed that mycorrhiza-like fungi had different methods in release of phosphorus from minerals and increase of P bioavailability in soil that can be used in the production of biofertilizers.

The present study evaluates the effect of various application methods of mostly applied antibiotics in agriculture (gentamicin, oxytetracycline, penicillin) at different concentrations on root and shoot growth indices and number of rhizobial nodules of chickpea plant and the count of total bacteria, fungi, and coliforms in the soil around the plant root after a growth period of 60 days in greenhouse as a split-plot design. Application of antibiotics, even gentamicin, raises plant shoot dry weight, compared to the control, with the lowest weight of 0.98 g/pot observed in the control (without antibiotic). Root dry weight in penicillin-applied treatments, especially at higher concentrations has been the highest (1.1 g/pot), and the lowest in gentamicin-applied treatments, especially when applied as seed coating (0.48 g/pot). In total, antibiotic application decreases the root to shoot ratio compared to the control. Application of all antibiotics increase soil bacterial count in the pots after 60 days in comparison with the control. Also, increasing the concentration of gentamicin and penicillin, decreases plant root nodule number by 78.8% and 59.7%, respectively. Overall, the effect of antibiotics on soil microbial count and plant growth depends on antibiotic type and application method.

About 98 % of the soil's potassium is in the form of minerals that are not available to plants. On the other hand, the continues use of fertilizers has unintended consequences for different habitats. Acid producing microorganisms can transform silicate minerals that contain potassium and release available potassium for plants. The aim of this study was to isolate and identify potassium, phosphorus and iron solubilizing bacteria from the minerals of these elements (potassium silicate, tricalcium phosphate, and hematite) from the soil around potato roots in order to make biofertilizers from plant growth-promoting bacteria.

Potassium solubilizing bacteria were isolated from the soil around potato roots. The isolates were tested and selected in terms of their ability to release potassium from three minerals (biotite, muscovite, and feldspar potassium) qualitatively by spot cultivation based on the emergence of the halo (Halo method) or changing the color of Aleksandrov medium. Then, to estimate the ability of the isolates for releasing potassium, they were cultured in Aleksandrov liquid medium. To investigate the ability for solubilizing t minerals,ricalcium phosphate the isolates were cultured in the same way as described above, but in the Pikovskaya medium. To investigate the ability for solubilizing iron, the modified Pikovskaya medium with hematite mineral was used. This study was performed by a completely randomized factorial design, in which, the minerals used in three levels (muscovite, biotite and feldspar potassium) were the first factor and 30 bacterial isolates were the second factor to release potassium. To analyze the release of phosphorus and iron, a completely randomized design was used and only the ability of 30 isolates for solubilizing of one mineral (tricalcium phosphate or hematite) was tested separately. Statistical analysis was performed with SAS software. Isolates were examined and identified using morphological, biochemical and molecular tests. Then, 10 superior isolates were identified and the plant growth promoting ability tests were performed on them.

Among 30 isolates, 10 top isolates were separated and identified for potassium, phosphorus and iron releasing ability. Flame photometric studies showed that the amount of potassium released by the isolates in the medium containing biotite was 647.18 mg/kg from control to 5416.16 mg/kg from number 10, in the medium containing muscovite was 148.68mg/kg from number21 to 2026.36 mg/kg from number 10, and in the medium containing potassium feldspar was 132.76 from number 7 to 534.88 mg/kg from number 19. The amount of phosphorus released by the isolates was 3582.85 mg/kg from control to 37011.42 mg/kg from number 25 and the amount of iron was 830.00 mg/kg from number 33 to 2661.66 mg/kg from number 4. In this study the released potassium from biotite and feldspar minerals by bacterial isolates was the highest and the lowest one, respectively. There was a high correlation between bacterial acid production and solubilizing minerals ability.

10 top isolates were separated and identified from the soil around potato roots based on evaluating potassium, phosphorus and iron releasing ability. In addition to being potent for releasing potassium, these isolates were also capable of producing auxin and siderophores, and also inhibiting pathogenic fungi (which are characteristics of PGPR bacteria). It is suggested to utilize these isolated bacteria in the production of biofertilizers to increase the bioavailability of potassium, phosphorus and iron for plants and to improve the growth and productivity of crops, especially potatoes. 

Veterinary antibiotics enter into agricultural soils through application in animal husbandry and manures where these soils could be the source of dissemination of antibiotics in soil and water habitats. Owing to increasing antibiotic applications in our country, the aim of present study was to understanding and evaluating the consequences of mostly applied antibiotics in soil (with and without organic and mineral conditioners) on extracellular enzymes activity, alkaline phosphatase and urease, and their resistance and resilience indices as well as mean soil enzyme activity, in a 90-day incubation period.

In the present study, the impact of releasing mostly applied antibiotics in soil (control (without antibiotic), gentamicin, oxytetracycline and penicillin) at different concentrations (50, 100 and 200 mg/kg dry soil) with and without organic and mineral conditioners (manure, biochar and nano-zeolite) on efficiency of soil alkaline phosphatase and urease enzymes and their resistance and resilience indices as well as enzymes efficiency index at 1-7, 7-30 and 30-90 days of a 90-day incubation as split-factorial design in which soil conditioners were as main plots and antibiotics and their concentrations were secondary plots.

In treatments without conditioner application, gentamicin at 200 mg/kg concentration caused 68.9 percent decrease in alkaline phosphatase efficiency compared to control (without antibiotic), however, decreasing enzyme activity in soil treated by 200 mg/kg oxytetracycline at control (without conditioner), application of manure, biochar and nano-zeolite compared to control (without antibiotic) was 17.5, 13.8, 17.5 and 16 percent, respectively. Urease enzyme efficiency at 30-90 days had an increasing trend and the highest enzyme activity recorded at this time period. Based on the results, measured enzymes had different responses, so that penicillin and oxytetracycline had not such a considerable impact of soil alkaline phosphatase activity. While, gentamicin and oxytetracycline at all applied concentrations, had significantly negative impact on soil urease activity. Considering the great responsivene of alkaline phosphatase to gentamicin antibiotic, application of soil conditioners had no significant efficiency in improving resistance of this enzyme in gentamicin treated soils. also, application of soil conditioners had no significant impact on increasing resistance index of urease enzyme in oxytetracycline applied soils. results show that increasing application amout of antibiotics caused decrease in soil enzymes activity and highest enzymes resilience observed in 50 mg/kg antibiotic concentration. Also results showed that urease enzyme had the highest resilience indec in penicillin application treatments followed by gentamicin and then oxytetracycline treatments.

Present study showed that application of conditioners, especially manure and its biochar improved soil properties and increased soil microorganisms’ resistance against antibiotics, even at higher concentrations. There was difference among responsiveness of studied enzymes, so that oxytetracycline had no significant impact on soil alkaline phosphatase activity, penicillin had no considerable effect on soil urease activity. Totally, the present study showed that application of soil conditioners could alleviate toxic impacts of antibiotics and result in increase in resistance and resilience indices of soil enzymes and improved enzymes activity and efficiency in antibiotic-treated soils.

Heavy metals are harmful to living cells, especially humans, animals, plants and microorganisms. The purpose of this study was evaluate the effect of soil and plant contamination on the abundance of endogenous bacteria or plants endophyte in two contaminated and non- contaminated soils. At the beginning, it was sampled from lead mining soils, the agricultural land around it and also from the aerial parts of the 8 plants grown in the soils mentioned. The concentrations of lead, zinc and cadmium were measured in the soil and leaves of the collected plants and counting of cultivated endogenous bacteria were performed. Investigation of soil and plant contamination showed that the concentration of heavy metals in samples taken from the mine soil is remarkably larger than the soil of agricultural land. The ability of plants to absorb metals was very different and the highest concentration of lead was observed in Mentha pulegium and the lowest was in convolvulus arvensis and the highest zinc concentrations was in Echinops echinatus and the lowest was in Euphorbia seguieriana Neck. The bacterial count showed that the abundance of bacteria in soils and plants grown in uncontaminated soils to heavy metals was low and against them in soils and plants grown in contaminated soils is considerably lower. Among the plants grown in contaminated soils, the average logarithm abundance of the bacteria cultivated on NA were the highest in the Senecio vulgaris and the cultivated bacteria on EMB were the most in the convolvulus arvensis.

The application of organic amendments is vital for poor soils of sugarcane fields in south Khuzestan. Recently, filter cake which is a byproduct of sugarcane factories rich in nutrients has received attention as a potential organic amendment. Therefore, an experiment was conducted to study the effects of sugarcane filter cake on selected soil quality indices at Haft Tape agro-industrial complex in 2014. The experiment was carried out in a randomized complete block design with three treatments including: 1- uncultivated, 2- sugarcane field with 100 kg ha-1 filter cake application for two continuous years, and 3- sugarcane field without filter cake (control), and three replications. Soil bulk density (BD), porosity (Pt), mean weight diameter (MWD) and geometric mean diameter (GMD) of water stable aggregates were determined in surface layer (0-30 cm). Moreover, the same properties as well as total organic carbon (TOC), active carbon (AC), total nitrogen (TN), available phosphorus (P) and available potassium (K), basal (BR) and induced (IR) microbial respiration, and alkaline phosphatase enzyme activity (PE) were compared in surface (0-30 cm) and subsurface (30-60 cm) of different treatments. Filter cake application resulted in significant increase in TOC (4.1 folds), P (7.4 folds), BR (1.5 folds), IR (1.9 folds), PA (1.6 folds), MWD (2.8 folds) and GMD (1.2 folds), as well as a significant decrease in BD (0.84 folds) compared to the control. The interactions of treatments and soil depth were exclusively significant for AC and TN. Available K was highest in uncultivated field (157 mg kg-1) with no significant disparity compared to filter cake treatment (135 mg kg-1). Furthermore, no significant improvement was detected in soil total porosity with filter cake application. The results suggest that short-term application of sugarcane filter is beneficial for soil quality improvement.

Survival of enteropathogenic bacteria in soil is a key factor to control waterborne diseases. The significance of zeolite nanoparticles in comparison with natural size particles on the survival of Escherichia coli in soil was studied in sterile and unsterile conditions. The experimental mixtures prepared by adding zeolite and nanozeolite at levels of 0, 5, 15% w/w to a loam textural soil to obtain 100 gr mixtures. Mixtures inoculated by a nalidixic acid resistance Escherichia coli (E.coli NAR) at a rate of 106 cells gr-1 soil. Results showed that in the unsterile soils, adding 5% zeolite had no significant effect on the survival of bacteria in soil and 15% nanozeolite reduced bacteria survival in soil especially at initial days of inoculation (about 3 log-unit). While adding 15% zeolite and 5% nanozeolite had a significantly positive effect on bacteria's time need to reach the detection limit (td). Sterilization of soil mixtures significantly enhanced bacteria survival in all treatments. The highest value of td obtained in sterile soil amended with 15% zeolite (46 days). In sterile mixtures adding nanozeolite caused an increasing in bacteria population at initial days after inoculation (about 1-1.5 log-units). Decreasing in the size of natural zeolite particles to nanoscale had a negative effect on survival of the studied bacterium in unsterile mixtures and E.coli NAR survived more in zeolite amended mixtures. While this negative effect was not observed in sterile soil. These results clearly showed that competition is the main factor that controls enteropathogenic bacteria's survival in soil.

Assessing biological indicators of soil quality is crucial to evaluation of ecological sustainability of agroecosystem. This study aimed at assessing the effects of four years of different tillage practices (no tillage, minimum tillage and conventional tillage) with and without canola cover crop on selected biological indicators of soil quality and sunflower yield in Dastjerd, Hamedan; A randomized complete block design with factorial arrangement and three replications was conducted. All the measured properties, including soil organic carbon, available P, basal microbial respiration, protease and phosphatase activity and sunflower seed yield were significantly (P

The organophosphate insecticides such as chlorpyrifos and diazinon have been widely used to control insects in home, agriculture, and veterinary. These compounds are a threat to public health and the environment; on the other hand, they have low degradation rate and therefore can be stable for a long time in soil. A major factor determining the fate of organophosphate insecticides in soil and water is biodegradation. Two diazinon and chlorpyrifos degrading bacterial strains were isolated from pesticides contaminated soils. The isolated bacterial strains were identified by 16S ribosomal RNA gene and fatty acid methyl ester analysis. Strong correlation was seen between microbial growth and the two organophosphates degradation. On average, bacterial strain 1 and 2 degraded 88.27% and 82.45% of initial applied diazinon in medium and degraded 81.07% and 88.35 % of initial applied chlorpyrifos during 20 days, respectively. The isolated bacterial strains were identified as Acinetobacter and Pseudomonas sp. The highest diazinon degradation were found by Acinetobacter and the highest chlorpyrifos degradation were found by Pseudomonas when cultivated in the mineral salt medium. Discussion and conclusion: The identified pure bacterial strains utilized chlorpyrifos and diazinon as a source of carbon. They were able to degrade most of the parental molecule in 20 days. Therefore, the isolated bacterial strains may have the potential for use in the bioremediation of diazinon and chlorpyrifos-contaminated soils.

In highly stressed ecosystems, symbiosis between plants and has beneficial effects on plant growth. The objective of this study was the effects of two dark septate endophyt fungi against mycorrhizal (Glomus mussea and Glomus interaradices) and Piriformospora indica on Spinach growth in without and with drough stress (Field Capacity (FC) and 50% FC). This study was done at Bu- Ali sina university of Hamedan greenhouse (2015-2016). The percentage of root colonization, wet and dry weights, contents of chlorophyll and some of micro- and macronutrients have been analysed in some adult treated plants after six weeks. The colonization results showed that all studied fungi can effectively enter into spinach roots. Inoculation with Glomus mussea increased the wet weight (20 g/plant) of the plants. Also, some morphophysiological and physological properties such as dry weight (4.1 g/plant), chlorophyll content (2.7 mg/gwd) and potassium to sodium ratio (8.4) were increased when plants inoculated with Curvularia specifera. However, high phosphorus content (311.2 mg/100gwd) measured in plants that was inoculated with Glomus interaradices. Generally, this study shows dark septate endophyte could be benefical in grwoth of spinach as much as mycorrhizal and Piriformospora indica symbiosis.

Soil is a finite natural resource and non-renewable under agricultural production without implementation of sustainable management practices. Ecological sustainability of agroecosystems can be comparatively assessed by soil quality evaluation, which in turn is assessed by soil quality indices. Soil quality is the general term used to refer to “the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, maintain the quality of air and water environments, and promote plant, animal, and human health”. Conservation tillage and use of cover crops are some of the sustainable agriculture practices that can improve the soil quality by adding organic matter and nutrients, and by acting as scavengers to trap leftover nutrients that otherwise might leach out. Cover crops are used as ground cover, mulches, green manure, nurse crops, smother crops, and forage and food for animals or humans. Given the significant role of tillage practices and crop residue management in soil quality improvement and crop production, a four-year field experiment was conducted to determine selected soil quality indices and Cucurbitapepo yield under different tillage and legume cover crop managements in Hamadan.
A four-year field experiment (2011-2014) was carried out at Bu-Ali Sina University experimental field in Dastjerd, Hamadan, as a factorial experiment in randomized complete block design with three replications. The area is located at 37 km of Hamadan, on 35◦ 01' N latitude and 48◦ 31' E langitude with 330 mm annual rainfall and 1690 m altitude. The treatments consisted of three levels of tillage practices (NT: no-till (direct seeding), MT: minimum tillage (chisel plowing disk) and CT: conventional tillage (moldboard plowing disk)) and two levels of cover cropping (C1: with legume cover crop (lathyrus sativus) and C0: without cover crop). These treatments were applied for four consecutive years in a way that lathyrus sativus as cover crop were planted in late winter for each year and returned to the soil surface with a trowel when 30% of the field was flowered. One week later, and prior to the cultivation of main crop, the mentioned tillage treatments were implemented. In the fourth year of the project,Cucurbita pepo was planted as the main crop. Soil and plant (Cucurbita pepo) were sampled early autumn (2014) and were analyzed for soil organic carbon, soil active carbon, macro and micro-aggregate carbon, mean weighted diameter of water stable aggregates, soil bulk density, basal microbial respiration and grain yield. Obtained data were analyzed using statistical software SAS 9.4 and the means were compared using LSD multiple range test at 5 percent level.
The results revealed that total organic carbon, active carbon, aggregate carbon, mean weighted diameter of water stable aggregates, bulk density, porosity and basal respiration were significantly affected by cover crop and tillage system so that the highest amount of these indicators were obtained in no-tillage system with cover crop treatment (NT-C1) and the lowest amounts were observed in the conventional tillage without cover crop (CT-C0). For instance, mean soil organic carbon increased from 0.4 percent in CT-C0 to about 0.7 percent in NT-C1. For majority of soil quality indices, no significant difference was observed between minimum and no-till; moreover, the application of cover crop in conventional tillage improved some aspects of soil quality. For instance, MWD was the highest (2.14 mm) in NT-C1, and was not significantly different with that of MT-C1 treatment. On the contrary, this index was significantly the lowest (0.48 mm) in CT-C0. The C. pepo grain yield was also significantly affected by tillage system, cover crop and their interactions. The highest grain yield (142.1 g.m¬-2) was obtained in MT-C1 treatment, which did not show significant difference with NT-C1 treatment. The lowest C. pepo grain yield (115.3 g.m¬-2) was observed in conventional tillage without cover crop (CT-C0) treatment, but it was in a same statistical group with NT-C0, MT-C0 and CT-C1 treatments. Cover crop increased organic carbon, active carbon, porosity, bulk density, microbial biomass activity and MWD by enhancing soil organic matter, probably; conservation tillage on its part further improved these effects by preventing the rapid decomposition of organic matter by reduced soil destruction, which eventually increased soil organic carbon, active carbon and production of stable aggregates.
Generally, after four years of applying different tillage practices and cover cropping, it was demonstrated that the integrated management of the conservation tillage (either no-tillage or minimum tillage) with legume cover cropping was the most appropriate management in the semi-arid region of Hamadan in view of selected soil quality indices and crop yield improvements.

Phosphate solubilizing bacteria play roles in phosphate solubilizing from mineral sources. These bacteria with different mechanisms make it soluble, some parts of solubilized P were absorbed in their biomass and the other parts, released in the soluble form which can be used by other organisms.
In this study, 24 bacterial isolates belonged to different genera such as Azotobacter, Pseudomonas, Rhizobium, Beijerinckia, Klebsiella, Agrobacterium, Alcaligenes, Sphingomnas, Microbacterium and Citrobacter were examined to determine solubilized P from two sources of phosphate (TCP and RP) in Sperber medium. This research was carried out in a complementary random design with three replications. At the end of incubation time, solubilized P in supernatant, amount of P in biomass and total solubilized P were measured.
The results showed that isolates are efficient in solubilizing P from TCP than RP. By decreasing pH, solubilized P was increased (r=0.775, pDiscussion and In most researches, solubilized P which is present in supernatant takes more attention but phosphorus in biomass is ignored which can be mineralized and available with a delay. This study showed that most parts of solubilized P were measured in microbial biomass. Hence, attention to this criterion could help us to select efficient PSB.

Growing evidence exists that agriculture affects antibiotic resistance in human pathogens. Beta-lactam antibiotics are the most commonly used antimicrobial agents in many countries. The abundance of beta-lactamase encoding genes can be used as an indicator of antibiotic resistance in the environment. So, to determine the beta-lactamase resistance genes, the abundance of culturable bacteria having bla-TEM genesin the soils under different land uses wasexamined.
44 Gram-positive and 34 Gram-negative bacteria plated on nutrient agar were isolated from agricultural, pasture and mining soils and selected to study the presence of TEM-class gene using PCR amplification. Antibiotic sensitivity test of bla-TEM諊╪힬솫 done adopting the Kirby-Bauer disk diffusion method and antibiotic discs used were: ampicillin, amoxicillin, vancomicin, streptomycin, tetracycline and gentamicin. Finally, five multi-drug resistant and bla-TEM isolates were identified using universal primers.
The highest level of beta-lactamase genes was observed in the Gram-positive and Gram-negative isolates from the pasture soils. In the agricultural and mining soils, a high abundance of bla-TEM isolateswasfound which also showed resistance to beta-lactam antibiotics. The identified multi-drug resistant and bla-TEM isolates were from these genera: Achromobacter, Bacillus, Brevibacillus, Aminobacter and Brevundimonas.
Discussion and The high number of bla-TEM bacteria in all the soils may be attributed to the other important feature of bla genes which is their capability to extrude toxic compounds like heavy metals in contaminated environments. Sensitivity of some bla-TEM bacteria to beta-lactam antibiotics was interesting. This result shows that bla-TEM genes confer resistance to beta-lactamase inhibitors in a different degree. Some of the identified isolates were pathogen. These pathogens in soils can transfer to plants and human which induce health problems. A high abundance of bla-TEM bacteria in the agricultural soil indicates the inefficiency of beta-lactam antibiotics.

The effect of chemical, biological and organic fertilizers and irrigation treatment on some growth indices and yield of sunflower (Helianthus annuus (L.) Var. Euroflour) were studied by a split-plot experiment based on randomized complete block design with three replications at Research Farm of Bu-Ali Sina University in 2015. Main plots consisted of two irrigation levels: optimum irrigation and deficit irrigation stress (irrigation after 60 and 120 mm evaporation from evaporation pan, class A, respectively) and sub-plots included of fertilizer treatments: 1- control (no fertilizer application), 2- full recommended dose of chemical fertilizers (NP), 3- vermicompost, 4- phospho-nitro kara, 5- vermicompost phospho nitro kara, 6- vermicompost ½ chemical fertilizers, 7- phospho nitro kara ½ chemical fertilizers, 8- vermicompost phospho nitro kara ½ chemical fertilizers, 9- ½ chemical fertilizers. Deficit irrigation reduced all traits, significantly. Growth indices, chlorophyll and carotenoid content, biological yield, seed, oil and protein yield increased as effected by fertilizer treatments. Generally, in optimum irrigation, maximum amount of mentioned traits were achieved in full dose of chemical fertilizers. But, in deficit irrigation treatment, biological and organic fertilizers, especially treatments of vermicompost ½ chemical fertilizers and phospho nitro kara ½ chemical fertilizers had the better rating than the full application of chemical fertilizers. In general, by comparing the studied fertilizers it could be concluded that bio and organic fertilizers with reduced doses of chemical fertilizers could provide sunflower nutritional needs, especially in deficit irrigation conditions.

Soil organic matter is influenced strongly by vegetation cover and management, therefore it is proposed as the main indicator of soil quality and health. The changes in soil organic matter status occur much more rapidly in the labile pools than in organic C. Thus, labile pools can be used as early indicators of changes in total organic matter that will become more obvious in the longer term here. In addition, the labile fraction has a disproportionately large effect on nutrient-supplying capacity and structural stability of soils. Land management as well as soil and environmental conditions lead to the deployment of different plant communities in rangeland ecosystems, which in turn may have different effects on soil quality indicators. The main objective of this research was to investigate the influence of different vegetation covers on the quantity and quality of soil organic carbon fractions in Gonbad experimental watershed, Hamadan. Moreover, the seasonal changes of selected soil carbon fractions were investigated.
Paired Gonbad watershed in Hamedan consists of two sub-basins: in control sub-basin no grazing management is applied, while in protected sub-basin, grazing has been restricted to a very short period in late autumn since 2002. Average annual precipitation and average annual temperature in the area are 304.4 mm and 9.5 °C, respectively (5). The soil cover of the watershed consists of TypicCalcixerepts, TypicHaploxerepts and Lithic Xerorthents (9). Five different vegetation typesof which, grasses (G), Astragalus-Bromus (A-B), Astragalus-Artemisia (A-A), Astragalus-Lactuca (A-L) in protected sub-basin, and Astragalus-Euphorbia (A-E) in control sub-basin, were selected. In addition, a formerly cultivated hilly land outside the watershed, now under rainfed wheat farming (RW) was selected as a non-pasture vegetation type. All of the six vegetation types were similar in terms of soil parent materials and slope aspect.. Soil and plant sampling were conducted in mid-autumn 2012 (a), and late spring 2013 (s). Three plots (1*1 m2) were studied in each vegetation type. Total organic carbon (TOC), carbon stock (CS), carbon stock normalized with sand(CS/Sa), active carbon (AC), normalized active carbon (AC/TOC), soil carbohydrates (Ch), normalized carbohydrates (Ch/TOC), basal respiration (BR) and normalized basal respiration (BR/TOC) were measured in surface soils (0-15 cm). A factorial experimental design with two factors, vegetation type (6 levels) and time (2 levels), was conducted. Prior to statistical analysis, data were normalized, if required.
TOC and CS contentswere significantly different between vegetation types. A-B and A-A had highest canopy cover, litter cover and species diversity. Species diversity in the rangeland ecosystems has direct effect on fodder production and soil organic carbon content. A-E site, despite its low TOC content, hadhigher CS/Sa (51.9 Mg/ha) due to higher amount of clay content, compared to A-A (43.1Mg/ha) with higher TOC content. The amount of AC andAC/TOC in different vegetation types is proportional to the amount of TOC, CS, total canopy, and the canopy and production of herbaceous species. AC content was significantly highest in A-B (711.7 mg/kg), and lowest in RW site(262.6 mg/kg). A-B site is rich in grass species with high amounts of readily decomposable root residues and exudates. The variation of carbohydrate contents in different vegetation types wasvery similar to that of total organic carbon, in that A-B and A-A exhibited the highest (5843 and 5258 mg/kg, respectively) and RW showed the lowest (1937 mg/kg) carbohydrate contents. The woody, not easily decomposible litters in A-A explainedthe high content of Ch/TOC (38.12%) in this site; low rate of humification entails increased soil carbohydrates. Ch/TOC was significantly lower in A-E than other covers. The highest BR andBR/TOC, were observed in A-B and A-A sites, mainly due to the high canopy cover, species richness,and soil organic matter. The lowest BR andBR/TOC were observed in A-E.Thesoil texture in this site was clay.The recirculation of organic matter in fine-textured soils is low because of organic materials protection from microbial decomposition. Total organic matter and labile organic carbon inputs werelower in A-L, A-E and G sites; this may explain the reduction of microbial activity in these vegetation types. Except for AC/TOC, Ch, and BR, seasonal changes of all other indicators were significant. Unlike other indicators, the content of Ch/TOC was significantly higher in autumn than spring.
Vegetation types had significant effects on selected soil quality indicators, so that A-A and A-B sites exhibited the highest soil quality, mainly because of higher vegetation cover, litter, and plant diversity. RW, followed by A-E site, demonstrated the lowest soil quality due to the tillage practices and low plant residue inputs in the first case, and overgrazing of vegetation cover and litter in the second. Total soil organic carbon and active carbon were significantly higher in spring compared to autumn. Seasonal changes of basal microbial respiration and carbohydrates were not statistically significant.

The study of symbiotic relationship between arbuscular mycorrhizal fungi (AMF) and medicinal plants is very important. Information about the symbiosis of medicinal plant species with AMF in the semi-arid regions of Iran is rare. This information allows increasing knowledge of the biology and ecology of these plant species.
The existence of AM symbiosis in 48 medicinal plant species (belonging to 9 families) was studied by root staining. Soil around the root of each species was sampled and analyzed for all soil properties which may be interrelated to AM symbiosis. The importance of different soil properties in AMF and plant biological relationship and the dependency of root colonization and spore formation by AMF on soil properties were statistically analyzed.
Among them Lepidium sativum, Brassica oleracea, Cheiranthus cheiri, Beta vulgaris, Spinacia oleracea, Malva sylvestris, Zygophyllum fabago, Arctium Lappa have not been colonized by AM fungi. Colonization and spore density of perennial plants were slightly higher than those of annual plants and were varied among different plant families. Soil texture and available phosphorous were the most important soil properties affecting fungal root colonization and spore numbers.
Discussion and Although in accordance with other researches, most of the medicinal plants from Brassicaceae family had no mycorrhizal symbiosis, a few of them had this type of symbiosis. Dependency of spore formation by AM fungi on soil properties was higher than dependency of root colonization percentage on soil properties. Increasing root colonization and spore numbers with increasing the percentage of sand and decreasing the percentage of clay and available phosphorous in soils show that plants are more depended on mycorrhizal symbiosis in hard environments and less productive soils.

Biosorption is one of the methods used for the separation of heavy metals from aquatic environments. The objective of this study was to investigate wheat straw humification and the capability of its microorganisms for the biosorption of Pb from aqueous solutions. Wheat straw (3 solution (0.001 N) with different Pb concentrations at pH 6. Among the Langmuir, Freundlich, and Temkine models, only the latter failed to fit Pb adsorption data. The highest sorption capacities (qmax) were obtained by the Langmuir model for the humified and unsterile sample (108.41 mg g‒1) and the lowest was obtained for the fresh and sterile sample (63.36 mg g‒1). Lead adsorption increased significantly with incubation time and its highest values were recorded with unsterile straw samples taken on days 1, 20, and 60 which were equal to 32.21, 43, and 60.96%, respectively, for the highest Pb concentration. The Langmuir constant (Kl) and Freundlich constants (Kf and n) were significantly higher for the more humified wheat straw samples compared to those for raw straw. All the adsorption parameters recorded higher values with the unsterile wheat straw compared to the sterile one, indicating the ability of the microorganisms to adsorb Pb from aqueous solutions.