جستجوی مقالات مرتبط با کلیدواژه « Bioremediation » در نشریات گروه « زیست شناسی »

Rana Valizadeh Kamran1, Lamia Vojodi Mehrabani2, Ali Aryan1 & Alireza Tarinejad11Corresponding author: Rana Valizadeh Kamran, [email protected]. 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.

Uranium, as one of the heavy metals, is a natural radionuclide that has harmful effects on human health and the environment due to its serious toxicity and radiation properties. Biosorption is a simple and cost-effective technique that can be used for remove of heavy metals and Radionuclides from waste waters. In this study, Micrococcus luteus biomass pretreated with autoclave heat was used. Then, physicochemical factor affecting the biosorption including biosorbent dose, initial uranium concentration, temperature and pH were investigated by Response Surface Methodology. The results showed that the factor of initial uranium concentration, sorbent dose and pH statistically (p-value‹ 0.05) affect the uranium biosorption process. In contrast, temperature factor (p-value› 0.05) statistically have no effect on uranium removal by M. luteus. Discussion and The results indicated that the pre-treated biomass under the conditions suggested by Design Expert software (19.75 g/liter of biomass, temperature 32.14 OC and pH 3.33) is able to remove approximately 99.98 percent of uranium from the contaminated area is 26.11 mg/liter of uranium, which shows its valuable potential in bioremediation applications of uranium from acidic wastewaters contaminated with low concentrations of uranium.

 Heavy metal pollution has increased worldwide. Bioremediation of toxic heavy metals in saline environments with conventional microbiological treatment processes is not feasible. Therefore, the use of halophilic and halotolerant bacteria need to be considered for the remediation of saline ecosystems. This study aimed to isolate and characterize toxic heavy metal-resistant and halophilic/halotolerant bacteria from the Lut desert.

 After sampling, halophilic/halotolerant bacteria were isolated on Moderate Halophilic media. Morphological and biochemical characterizations of isolates were carried out. Each isolate's heavy metal resistance was identified by an agar dilution method and the Minimum Inhibitory Concentrations (MIC ) of each heavy metal was determined. Then, sixteen strains were randomly selected and subjected to 16S rRNA gene identification.

 The least toxicities were found with selenite and arsenate on 74 selected isolates, while mercury exhibited the highest toxicity. The maximum MIC values of cadmium, copper, and  chromium were the same. Although, the MIC value of zinc was significantly less. The remarkable resistance toward lead, selenite, and arsenate was reported. Phylogenetic analysis revealed that most strains belong to the Bacillaceae family and Bacillus genus. 

Selected halophilic/halotolerant bacteria from the Lut desert had considerable  resistance to heavy metals. Therefore, these strains could be considered for further investigations of the mechanisms involved in heavy metal resistance of halophilic and halotolerant bacteria or for bioremediation of polluted saline environments.

There are various methods to remove oil pollution from natural sources, which biological methods seem to be more appropriate methods due to their cheapness, sustainability and biodegradability. So, the aim of the present study was to isolate and identify the bacteria which able to degrade oil from contaminated soils to determine the optimal conditions for decomposition of these compounds in complementary studies. Soil sampling was performed from contaminated areas around the Tehran refinery and after isolating oil-degrading bacteria in a culture medium containing 2% kerosene (as the only carbon source), the ability of separated isolates to oil degradation were evaluated using FTIR and GC-MS. Finally, these isolates were identified using morphological, biochemical and molecular methods.Results and The results showed that, three oil decomposing isolates were able to reduce or eliminate the aromatic compounds from the oil. They decomposed oil complex alkanes into simpler alkanes. So in their culture medium, substances with amine and carboxyl functional groups (organic compounds) were observed. The identification of these three isolates showed that they belong to the species Nocardia sp, Bacillus subtilis and Acinetobacter baumannii. As conclusion, the use of this biological method can be a good alternative for physical and chemical ones. Isolation of native soil bacteria that have adapted with petroleum products in the soil can be helpful for bioremediation.

Owing to the high cytotoxicity, introduction of anticancer pharmaceuticals to the encironment via pharmaceutical and hospital effluents is regarded a major health threat for eukaryotes. Exploring bacterial cells, as prokaryotic organisms, could be a novel approach for the removal of these compounds. Therefore, in this study, we aimed to isolate and identify oxaliplatin degrading bacteria from pharmaceutical wastewater samples and to evaluate their oxaliplatin removal potential as single and multi-species systems.

Bacterial isolation was performed using the membrane filtration method and the inhibitory effect of the drug for the isolated bacteria was evaluated in 96-well plates. Finally, oxaliplatin removal efficacy of the single and multi-species bacterial populations was determined using the High-Pressure Liquid chromatography (HPLC).

A total number of five bacterial species, including Enterobacter agglomerans, Citrobacter youngae, Xenorhabdus nematophilis, Bacillus lichineformis and Moraxella spp.able to degrade oxaliplatin were isolated. The highest and least oxaliplatin degrading potential was observed for B. lichiniformis (52%) and E. agglomerans (21%), respectively. Also, the multi-species treatment containing B. lichineformis, X. nematophilis, E. agglomeran showed the highest oxaliplatin removal efficacy (79%).

This work reveals that the bacteria isolated from pharmaceutical effluents could be employed for oxaliplatin removal and could be considered as a novel approach for the reduction of pharmaceutical pollutants.

Catechol 2,3-dioxygenases play a key role in the metabolism of aromatic molecules in the environment by soil bacteria. The aim of this study is to introduce the new catechol 2,3-dioxygenase and also to survey bioinformatics and biochemical characteristics in the presence of various substrates as well as to study its activity in various pH ranges for the widespread use of such enzymes in bioremediation industry.In this study, the DNA sequences of Catechol 2,3-dioxygenase were separated from Aneurinibacillus migulanus Znu12 and recorded with accession number MN197546.1 in NCBI, then it was cloned in plasmid pET28a. The accuracy of cloning and not changing the frame shift was confirmed by sequencing. After transferring of plasmid into E. coli BL21 (DE3) cells, protein expression was assessed by SDS-PAGE. Afterwards, the purification, assay and optimization of enzyme activity were evaluated.The results of PCR reaction on agarose gel indicated a sequence of 912 bp, an enzyme with 304 amino acid residues. Results of sequence alignment by ESPript3 server also confirmed highly conserved residues of His199 and Tyr 255 in the enzymes active site. Biochemical characterization of the enzyme showed that the enzyme had the highest (100%) activity at pH 7.2, while it had only 70% activity at pH 7.4. As compared with pyrogallol and phenol, catechol by optimal concentration of 0.032 was the most preferred substrate for the enzyme. Bioinformatics results confirmed also such substrate preference based on the type and position of amino acid residues in the enzyme active site.

Today bioremediation by microalga is an effective method to remove radionuclides and heavy metals from wastewater. Bioremediation of radionuclides and heavy metals is an efficient method of treating heavy metal contaminated effluents. In this study, the bioremediation of uranium from aqueous solutions was evaluated using live microalgae Chlorella vulgaris in a batch system. The Plackett-Burman method by Minitab statistical software was used to screen for effective factors such as initial uranium concentration, temperature, time, pH and amount of biomass on the removal of uranium by C. vulgaris. The results showed that the initial uranium concentration and pH factors were statistically effective by software. Optimization of effective factors in uranium bioremediation was evaluated by the response surface methodology (RSM). To determine the main effects and interaction of factors affecting uranium removal by C. vulgaris, central composite design (CCD) was used. The experimental data were then processed and the equation was evaluated to match the experimental data, and then the optimal removal values were determined. Finally, the results showed that C. vulgaris in optimal conditions proposed by Design-Expert software can remove 99.63% of existing uranium from aqueous solutions containing 7.1 mg / l uranium with pH 4.3.

Application of oxygen releasing compounds (ORCs) is considered as a novel method in petroleum hydrocarbon remediation from groundwater. ORCs destroy chemically the contaminant by exposure to water which results in hydroxyl radical generation or biologically remove the pollution by biostimulation of the groundwater native microorganisms aerobically. In the present study, calcium peroxide (CaO2) nanoparticles were applied to supply the required oxygen for growth and activity of the native microorganisms to consume naphthalene (20 ppm) as a carbon source. Additionally, the effect of CaO2 content, temperature and pH on the performance of nanoparticles were investigated in the naphthalene removal. The results indicated that the microbial population was sharply increased in the presence of 400 mg/L of nanoparticles and at 30oC and the contaminant was completely removed after 20 days at neutral pH. Furthermore, naphthalene was 100% remediated from groundwater at pH 3, 7.4 and 12 after 2, 20 and 30 days, respectively. This proved the acceleration of chemical oxidation under the acidic condition. At 15 and 30 ± 0.5 oC the contaminant was removed from the media within 15 and 20 days respectively. Meanwhile, only 75% of contaminant was remediated from groundwater within 30 days at 4 ±0.5oC which was due to the reduction in the biological activity and the chemical reaction rate.

Environmental pollution with heavy metals is increasing with the development of the industry. The aim of the present study was to examine the isolation and molecular identification of chromium-resistant bacteria from contaminated wastewaters to investigate the bioremediation of chromium by them.

Chromium-resistant bacteria were isolated from tannery and leather factory effluents. The temperature, pH, BOD, COD, and the amount of heavy metals in each sample were determined. Bacterial isolation was performed by the agar dilution method in the presence of different concentrations of chromium from 1 to 128 mmolL-1. Then, the MIC and MBC for the selected strains were determined. The molecular identification of the resistant strains was done by colony PCR. The biological removal of chromium was evaluated by the selected strains under in vitro conditions.

The results of the study showed that the temperature, pH, BOD, and COD in the leather factory effluent were 28.7 ° C, 7.10, 100, and 330 mgL-1 and in the tannery effluent were 26.03 ° C, 6.84, 110, and 480 mgL-1, respectively. In this study, Bacillus subtilis H1F and Bacillus sp. H1D were isolated from leather wastewaters and Bacillus cereus H2C was the selected strain from tannery effluents. Among them, B. subtilis H1F showed the highest chromium resistance with an MIC value of 64 mM. Chromium removal of this strain was 68.5 ppm and it had the highest capacity among the three selected isolates.

Considering that B.subtilis H1F had the highest resistance and adsorption of chromium compared to other two bacteria, it is a suitable candidate for the biological removal of chromium from polluted effluents.

Pollution caused by oil extraction processing stimulates the growth of petroleum hydrocarbon-degrading bacteria. Bioremediation, a process that utilizes the capability of microorganisms to degrade petroleum hydrocarbon compounds, is emerging as a promising technology for the treatment of soil and groundwater contamination. This paper aimed to separate petroleum-degrading bacteria and to investigate their applicability in the bioremediation of petroleum-contaminated soils.

Sampling was done from the soil of a refinery area. A mineral culture-medium environment containing n-hexane was used for isolation. Isolated bacteria were identified by biochemical methods and 16S rRNA sequencing. Phytotoxicity test was performed by measuring the percentage of Lepidium sativumm seed germination. Contaminated soil bioremediation was performed using the selected strains in the laboratory and the environment over three months.

A total of 19 bacteria isolates capable of growing on mineral medium containing n-hexane were isolated. Among the isolated strains, four strains had the highest ability to biodegrade the petroleum compounds of anthracene, naphthalene, and phenanthrene. By the molecular identification method, the selected strains were identified as Stenotrophomonas maltophilia (SB10),  Bacillus subtilis subsp.spizizenii (SB7),  Streptomyces ambofaciens (SB14), andCupriavidus respiraculi (SB16).  The treatment of petroleum-contaminated soils using S. maltophilia (SB10) increased the population of petroleum-degrading bacteria from 5.2×103 to 1.4×104 at the end of the third month. The rate of biodegradation of the total petroleum hydrocarbons reached 80% and the germination power of Lepidium sativumm reached 68% at the end of the third month.

The addition of the selected bacterial strains to soil contaminated with petroleum compounds increased the population of degrading bacteria. The use of degrading bacteria along with sawdust improved the purification of petroleum-contaminated soils.

One of the new methods in reducing the pollution caused by the use of herbicides and other agricultural chemical pesticides is the use of resistant and degrading bacterial isolates of these herbicides. This study was conducted to isolate and identify resistant bacterial strains from the soil of wheat fields using the three herbicides of Othello, Atlantis, and Puma Super.

To isolate and characterize resistant bacteria, samples were collected from wheat fields treated with Othello, Atlantis, and Puma Super herbicides. Isolates were selected based on the growth on the Standard Succinate Medium containing 10 percent of the mentioned herbicides. The representative isolates were identified based on biochemical tests and amplification of the 16S rRNA gene. Also, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the representatives were measured.

A total of 17 isolates could grow on a growth medium containing 10% of the tested herbicides. Based on the valid biochemical and molecular test results, the representative strains were identified as Stenotrophomonas maltophilia, Ensifer adhaerens, Xanthomonas sp., Pseudoxanthomonas sp., and Acinetobacter sp. The Minimum inhibitory concentration (MIC) and Minimum Bactericidal Concentration (MBC) were attributed to Othello (0.28 and 0.4) and Atlantis herbicides (0.35 and 0.5) belonging to Acinetobacter and Xanthomonas (0.45 and 0.67) for Puma Super herbicides.

According to the results of this study, herbicide-resistant bacteria identified in this study can be useful in plant biotechnology applications in polluted areas and can reduce environmental pollution regarding using these herbicides. However, further studies are needed in order to identify the degrading potential of the resistant strains.

Azo dyes are the most important and widely used dyes in various industries. This group of pollutants is a threat to aquatic life. In the present study, the effect of three different concentrations (0, 10, 20mg/L) of the basic red 46, (BR46) on the physiological characteristics of aquatic fern Salvinia natans was evaluated at the 7-day treatment period. Also, the ability of S. natans for bioremoval of BR46 was evaluated. The results showed that chlorophyll a and total chlorophyll content, despite chlorophyll b, decreased at 20mg/L concentration. At 20 mg/L of BR46, relative growth rate and effect index decreased and increased, respectively. Total carotenoid concentration was increased by 72% at 20mg/L. Cyanidine glycoside concentration, lipid peroxidation and antioxidant activity increased in the presence of 10 and 20 mg/L of BR46. On day 7th, the highest bioremoval efficiency was observed in the presence of 20mg/L BR46. Thus, S. natans has the ability to remove BR46 from contaminated water but the presence of both 10 and 20mg/L of dye induced antioxidant activity and the risk of oxidative stress for S. natans.

This study was conducted to identify 16S rDNA in the superior phenol-degrading bacteria for phenol bioremediation purposes. Two strains were selected as superior ones with higher phenolase activity and investigated in culture media with different pHs, temperatures, and carbon and nitrogen sources. The first strain removed 100% phenol in the medium contained 0.3 g/L phenol as carbon source, 0.2 % peptone and ammonium chloride as nitrogen source after 24 h, at 35 ºC in pH 7. While the second strain removed 100% phenol in the medium contained 1 % sucrose, 0.3 g/L phenol as carbon source, 0.2 % yeast extract and ammonium chloride as nitrogen source after 24 h, at 30 ºC in pH 7. The results of sequencing and alignment of 16S rDNA sequence revealed that the first strain belongs to Aneurinibacillus migulanus and the second one to Paenarthrobacter nitroguajacolicus. Overall, the two selected strains from the research could be considered as an appropriate candidate in phenol bioremediation purposes.

The present study was conducted to identify the resistant bacterial strains from Kermanshah oil wastewater based on molecular 16S rDNA PCR sequencing and the investigation of their growth in different chromium concentration. To identify 16S rDNS, 94 samples were isolated from Kermanshah oil wastewater. Sequencing the best strain for most removal was conducted. Bactria were identified by morphology, Gram staining, Biochemical tests, Standard microbiology. Cr (VI) was incubated in the concentrations of 25, 50, 100 and 150 mg/ml for 96 h. The maximum Cr biosorption (0.35 ppm) was observed at 28°C and a pH=7.5-8. Biological oxygen demand was 126-530. The most isolates had a need from 7.2-7.90 for chemical oxygen demand. Based on obtained results, Klebsiella variicola, Bacillus aerius, Bacillus stratosphericus and Lysinibacillus fusiformis were most resistant strains. Bacteria growth was higher in control, 25, 50, 100 and 150 mg, respectively. All the bacteria showed a fix growth after 72h. Considering high resistant of Klebsiella variicola, Bacillus aerius, Bacillus stratosphericus and Lysinibacillus fusiformis, the strains can be used for bioremediation of chromium and decreasing aontaminations, especially in oil refinery.

 Removal of undesirable pollutants from aquatic ecosystems, which is caused by discharge of large amounts of industrial and urban pollutants into water resources, requires efficient, cost-effective and environmentally friendly technologies, such as phycoremediation. In this biological process, the physiological ability of some algal and cyanobacterial species in detoxifying pollutants such as textile dyes is used. In the present study, the ability of eukaryotic green alga Chlorella vulgaris and prokaryotic cyanobacter Spirulina platensis for decolorization of Direct Blue 129 (DB129) dye at zero (control), 20 and 60 mg. L-1 was studied during one week. Evaluations of physiological indices were performed on 1, 3 and 7 days of growth. C. vulgaris showed a higher percentage in removal efficiency than S. platensis. Dye treatment increased growth indices; Xm (maximum cell concentration), Px (cell productivity) and µm (maximum specific growth rate) and decreased td (doubling time) in C. vulgaris, compared to the control, but astaxanthin showed a higher increase in S. platensis. Chl a, Chl b and total carotenoid contents were increased in C. vulgaris alga at both concentrations of dye, and at 20 mg. L-1 in S. platensis, compared to control. Phycobilins were also increased in treated S. platensis. The highest concentration of dye (60 mg. L-1) caused the highest soluble carbohydrate production in both microorganisms. Along with an increase in dye concentration (unlike S. platensis) protein content was also increased in C. vulgaris. In general, it seems that C. vulgaris has a higher ability in decolrization and is more tolerant to DB129 dye stress than S. platensis.

Iron, one of the essential micronutrients, is needed for electron transport and metabolic processes in almost all living organisms. The ferric form (Fe3+) of iron is insoluble in nature and inaccessible at physiological pH (7.35–7.40). Under iron-limited conditions, metal-chelating agents such as siderophores are synthesized by many bacteria and a few fungi. Siderophores have a high affinity for iron or other metals. In recent years, siderophores have been considered due to their potential applications in different aspects. Siderophores have applications in microbial ecology to enhance the growth of several unculturable microorganisms and can alter the microbial communities. In agriculture, siderophores are used as plant growth promoters by enhancing the Fe uptake by plants and as potential biocontrol agents against phytopathogens. Therefore, they are suitable alternatives for chemical pesticides. Also, siderophores can be applied in the bioremediation of heavy-metal- contaminated samples and as a biosensor. In this article, the different uses of these iron-chelating molecules are highlighted.