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In this study, fungal strains with crude oil biodegradation activity were screened from Shazand oil refinery (Arak). Twelve fungal strains were isolated in PDA medium. TPH assay in the presence of 1% of crude oil showed that the ADH-02 was the most capable strain of oil degradation with an efficiency of 75%. FTIR analysis was revealed that 91% of aliphatic hydrocarbons were degraded by ADH-02. This strain proved to belong to Gliomastix genius with a similarity of 99%. Polycyclic aromatic hydrocarbons degradation analysis with HPLC demonstrated that this strain is capable of removing 67% of anthracene in 14 days. The results showed that Gliomastix sp. was a potent fungal strain in bioremediation of crude oil and polycyclic aromatic hydrocarbon.

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

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

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Rana Valizadeh Kamran¹, Lamia Vojodi Mehrabani², Ali Aryan¹ & Alireza Tarinejad^1
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Corresponding author: Rana Valizadeh Kamran, rana.valizadeh@gmail.com

Abstract. Bioremediation is a promising strategy to reduce the concentration of heavy metals that their increase in the soil was the result of the development of industries and factories in the area, threatening the environment and human health. To investigate the effect of the heavy metal chromium and the reduction of its toxic effects by bacteria (at two levels of the absence of bacteria and the presence of bacteria in Hoagland's solution), a factorial experiment was conducted as a completely randomized design with three replications and the morphological, physiological traits and plant elements were measured in the applied treatments. The results showed that the experimental treatments did not affect plant yield traits, fresh weight, stem length, and leaf length. Leaf width, chlorophyll a, b, and plant phosphorus content decreased under chromium stress and increased with bacterial treatment. Hydrogen peroxide, malondialdehyde, ascorbate peroxidase, superoxide dismutase, catalase, proline, solid soluble substances, phenol, flavonoid, and anthocyanin, as well as the content of plant elements such as chromium, nitrogen, and potassium, increased due to the chromium treatment. Using bacteria in the culture medium containing chromium, significantly decreased the hydrogen peroxide and malondialdehyde, indicating a reduction in the oxidative stress. The non-enzymatic and enzymatic antioxidants of plats in the bacterial treatments increased, indicating bacteria's role in strengthening the plant's antioxidant system. The chromium content of the plant decreased after the use of bacteria. The results showed the positive effect of using chromium-purifying bacteria in the environment of plant cultivation in reducing the harmful effects of chromium heavy metal stress.