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Total petroleum hydrocarbons (TPHs) is one of the most important environmental challenges. Phytoremediation of oil-polluted soil depends on microorganisms of the rhizosphere. This study attempts to evaluate the microbial impact of Zea mays rhizosphere during a 60 day period using three different treatments: control soil, oil-polluted soil and oil-polluted soil including fertilizer (NH₄No₃, K₂HPO₄). Then, the rhizosphere bacteria were identified. The results showed that CFU per gram of control soil was higher than other treated soils, an indication of oil stress on microbial population. In addition, more bacterial diversity was observed in soils and different bacteria were isolated from the soils. Finally, the most resistant bacteria to the oil pollution were assayed. The assay of isolates indicated that all of those separated from the oil-polluted soil have the ability to produce biosurfactant in different quantities. Further investigation must be carried out to optimize the degradation of oil by these isolates. 

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Three types of chitin as α (exoskeleton of crustaceans), β (cuttlebone of cephalopods) and γ (some fungal cell wall) exist in nature. Chitosan is the most important derivative of chitin, which has various biological activities. In this study, α, β and γ-chitosans were extracted from Portunus segnis exoskeleton, Sepia pharonis cuttlebone and Aspergillus niger cell wall, respectively. Samples of crab and sepia from Bandar Abbas coastal waters were gathered in the summer of 2014 and samples of Aspergillus niger (PTCC 5223) were obtained from the Iranian Research Organization for Science and Technology (IROST). The amount of chitosan extracted from the Crab was significantly higher than other samples. Antimicrobial properties of these three types of chitosan were explored against 9 bacterial and 2 fungal strains using disc diffusion method. On average α chitosan and γ chitosan revealed to have highest and lowest antimicrobial activities, respectively. Antibacterial properties of chitosan extracts were more than their antifungal properties. Gram negative bacteria as well as gram positive bacteria were sensitive to three types of chitosan. According to observed results, all three types of chitosans have good antimicrobial activities, and further investigations are suggested.

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



 

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Nepeta binaludensis jamzad, as a medicinal plant, which is at risk of extinction due to irregular harvesting and damage of its habitat. Four treatments including: 1- inoculation with Azotobacter chooroccum, 2- inoculation with Bacillus cereus and Pseudomonas putida, 3- inoculation with a mix of three bacteria (A. chooroccum + B. cereus + P. putida) and 4 controls (without inoculation), in the form of a completely randomized design with 3 replications in two vegetative growth stages (ten and twenty weeks after sowing). Plant growth-promoting bacteria (PGPB) improved all the evaluated morphological characteristics, including the length and dry weight of the aerial part, total leaf area and root length compared to the control. Also, the results of biochemical investigations showed that in 10 and 20 weeks old plants, the application of PGPB could increase the phenolic and flavonoid compounds and also antioxidant activity. The contain of some elements such as calcium, potassium, phosphorus, iron and magnesium also increased as a result of inoculation with PGPB. Since the PGPB improved the growth and also increased the effective compounds of N. binaludensis plants, they can be introduced as useful bio fertilizers and considered as a good alternative to chemical fertilizers.