Contamination Problems Research Articles

Pesticides in Foods: Towards Bioremediation Biocatalysts?

The presence of hazardous chemical compounds in foods is a growing concern in almost every country. Although some toxins come from microbial contamination, a major part comes from residues of pesticides used for plant health and food preservation. Despite plans to decrease their use, the concentration of hazardous residues encountered in food is growing. The societal solution to this issue is to find alternatives to chemicals and replace the most hazardous by biodegradable, fewer toxic compounds. However, as this greener transition takes some time, any transitory solution to decrease the risks of contamination is welcome. Among them, the stimulation of microbial pesticide degradation in food in a similar way to bioremediation in the environment would be very positive. In this review, we present the problem of food contamination, focusing on organophosphates and organochlorines, and the various possibilities of microbial decontamination. We discuss the possible use of microbial biocatalysts as a biopreservation tool. We conclude that, although this process is very promising, it lacks research taking into account the various degradation products and the elaboration of screening procedures able to choose some rare, efficient biopreservation strains.

Removal of Malachite Green Dye from Aqueous Solution Using Lemon Leaf Powder as an Adsorbent

The majority of developing nations experience significant water contamination from textile sector wastewater. The use of low-cost, environmentally friendly adsorbents has been researched as a means of addressing problems of water contamination and high costs for waste - water treatment processes. Malachite green is an incredibly dangerous colour that not only damages mammalian cells but also has a key influence in the growth of liver cancers. The life cycle of aquatic creatures, plants, and people is hampered by dye released into bodies of water without sufficient treatment. In this study, the powdered lemon leaves are utilized for removal of the aniline green dye. By using batch-style setting and design of the experiment (the Box– Behnken technique) adsorbent has been investigated & have been developed to evaluate the process's critical factors, including agitation time, size of adsorbent, dosage of adsorbent, pH, initial concentration and temperature. The acquired values were fitted with adsorption isotherms. Malachite green dye sequestration onto Lemon Leaf Powder was chosen using kinetic models. The results of the trials showed that employing powdered lemon leaves, malachite green could be removed to a maximum of 82.21%. Malachite green dye concentration of 50 mg/L, temp of solution 303 K, and dosage of adsorbent 20 g/L are the ideal parameters. Lemon leaf powders have a maximum sorption capacity (qmax) of 8.08 mg/g. The equilibrium was more accurately modelled using the Freundlich isotherm. When compared to other models, the data which fits the pseudo 2nd order kinetics model is better. Previously researchers had proved several low– cost materials such as wheat bran, marina alga, wood apple shell etc In the current work, to remove malachite green dyes the efficacy of citrus lemon leaves is thoroughly done. The operating parameters that are optimized include dye solution concentration, initial solution pH, sorbent dose, and temperature. Studies on thermodynamics have demonstrated that the adsorption process was endothermic & spontaneous.

Mechanism of acid and alkali electrolyzed water on the elimination of Listeria monocytogenes biofilm based on proteomic analysis

Acidic electrolyzed water is a relatively mature bactericide, which has a certain inhibitory effect on a variety of microorganisms, and is widely used in the field of food processing for cleaning, sterilization and disinfection. This study investigated the deactivation mechanisms of Listeria monocytogenes by Tandem Mass Tags quantitative proteomics analysis. Samples were treated through A1S4 (Alkaline electrolytic water treatment for 1 min and Acid electrolytic water treatment for 4 min), S3A1S1 (Acid electrolyzed water treatment 3 min, Alkaline electrolyzed water treatment 1 min and Acid electrolyzed water treatment 1 min), S5 (Acid electrolytic water treatment for 5 min). Proteomic analysis showed that the mechanism of acid alkaline electrolyzed water treatment to eliminate the inactivation of the biofilm of L. monocytogenes was related to protein transcription and extension, RNA processing and synthesis, gene regulation, sugar and amino acid transport and metabolism, signal transduction and ATP binding. The study on the influence mechanism and action mechanism of the combination of acidic and alkaline electrolyzed water to remove L. monocytogenes biofilm is helpful to understand the development of the process of removing biofilm by electrolyzed water, and provides theoretical support for the treatment of other microbial contamination problems in food processing by electrolyzed water.

Effect of Different Arsenic and Biochar Levels on Soil Microbial Population and Enzymatic Activity

Arsenic (As) poses a pervasive environmental contamination problem on a global scale. Human activities have significantly contributed to the extensive presence of arsenic (As) in soils. Recently, there has been growing interest in exploring the potential of biochar in addressing the issue of As-contaminated soils. This study focused on evaluating the effects of two types of biochar, namely straw biochar and iron-modified biochar, on the composition of soil microbial communities and enzymatic activity in soil contaminated with arsenic. After conducting a pot experiment for a duration of 9 months, the microbial communities and enzymatic activity were analyzed. Biochar refers to carbon-rich porous solids that are produced by heating biomasses under low oxygen conditions. These biochars are regarded as environmentally friendly sorbents that can be employed for the treatment of different types of arsenic contamination. The increased abundance of soil microbial populations and the enhanced enzymatic properties suggest that biochar fosters the richness and diversity of bacterial communities. Consequently, these improvements in the soil environment and biological quality highlight the potential of iron-modified biochar as an alternative agent for remediating arsenic-contaminated soils.

ASSESSMENT OF THE IMPACT OF GROUNDWATER TABLE FLUCTUATIONS ON THE TRANSFORMATION OF SUBSURFACE CONTAMINATION WITH PETROLEUM PRODUCTS

This paper describes the actual problem of groundwater contamination with petroleum products and its transformation under the influence of climatic factors. The global experience of studying the influence of groundwater table fluctuations on the transformation of petroleum contamination, in particular, the processes of redistribution of mobile petroleum products, dissolution, evaporation, and biodegradation of hydrocarbon compounds, as well as the difference between the actual thickness of a mobile petroleum product layer in porous media and the apparent thickness of a mobile petroleum product layer in a monitoring well was analyzed, which is important to plan remedial actions. The impact of groundwater table fluctuations on transformation of the petroleum contamination source within the warehouse of fuels and lubricants of the Boryspil airport was studied. As a result of groundwater table fluctuations, kerosene was “smeared” in the vadose zone, which led to an increase in the soil contamination area. During the observation period, a mobile kerosene layer almost disappeared when a groundwater table rose and restored when a groundwater table decreased, while the vadose zone was additionally contaminated since a new capillary zone was formed during each rise ofa groundwater table and kerosene. The long-term amplitude of groundwater table fluctuations was 2.4 m, and apetroleum contamination zone was also within these limits. During the observation period, the largest area of groundwater contamination with dissolved petroleum products was observed at the lowest groundwater table elevations in 2016. The highest concentration of dissolved hydrocarbons in groundwater (75.98 mg/dm3) wasfound within amobile kerosene lens. Beyond the mobile kerosene lens, spreading of groundwater contamination with dissolved hydrocarbons is limited. The analysis of the monitoring data of the petroleum contamination source within the warehouse of fuels and lubricants of the Boryspil airport indicates that at present subsurface contamination with petroleum products is localized, and its further spreading is not expected. It is recommended to continue in the future monitoring of the natural attenuation of subsurface contamination.

Strategic routes for wastewater treatment plant upgrades to reduce micropollutants in European surface water bodies

The European Union is determined to address the problem of contaminants of emerging concern (CEC) occurrence in natural water bodies. However, if a broad range of possible advanced treatment technological solutions exists as well as a variety of possible future conditions, then emission and consequently strategies for wastewater treatment plan (WWTP) upgrade and operation are not easy to anticipate. Here, a strategic foresight exercise was carried out to support decision-making matching anticipated future conditions toward the goal of finding suitable treatment upgrades to control CECs release in the environment. As a result, a roadmap and strategic routes were developed based on the interpretation of drivers for the EU region in the context of Shared Socioeconomic Pathways (SSPs) global change narratives. Screening and ranking of WWTP tertiary and advanced treatment technology upgrades were performed. Analysis of the resulting envisioned strategic routes allowed identifying and confronting core challenges such as the CEC removal agenda, technologies’ performance, requirements for CEC removal and water scarcity. The results also underline opportunities to shape WWTP technological upgrade planning such as: enhancing circular economy solutions in WWTP, water reclamation, and accelerated increase of the technology readiness level of hybrid and nature-based solutions.

Evaluation of the impact of the intensive exploitation of groundwater and the mega-drought based on the hydrochemical and isotopic composition of the waters of the Chacabuco-Polpaico basin in central Chile

A hydrogeochemical and isotopic study has been carried out to understand the hydrogeological functioning of a small alluvial aquifer in central Chile in a context of mega-drought and intensive exploitation of its waters. Additionally, two mine tailings dams from porphyry copper mining are situated in the area. The prolonged mega-drought, which has lasted for over thirteen years, has resulted in a significant decrease in rainfall recharge and a drop of up to 50 m in piezometric levels, although no serious groundwater contamination problems have yet been detected, except for a rise in nitrate contents (ranging between 23 and 45 mg/L NO3) attributed to return irrigation. Groundwaters are calcium-bicarbonate and calcium-sodium-bicarbonate in composition. The values of δ18O and δ2H of the alluvial aquifer indicate fractionation by evaporation that would be explained by the recirculation of water that occurs in the agricultural areas of the basin, where the excess irrigation water that go back to the aquifer presents fractionation by evaporation. The δ34S and δ18O of dissolved sulfate point to pyrite oxidation, which could be related to the pyrite present in the copper porphyry and recognized in the Andes Cordillera. The 87Sr/86Sr isotopic values of the alluvial aquifer waters are close to the isotopic fingerprint of the volcanic rocks of the Abanico Formation. However, the water from the wells located further downstream in the basin and close to the tailing dams show δ34S and δ18O of dissolved sulfate and 87Sr/86Sr consistent with Miocene intrusive mineralogies of the copper porphyry type. The groundwater chemistry does not show water seepage from the tailings dam. Therefore, a minor contribution of minerals related to the intrusive rocks is proposed, which would originate from the movement of fine particles by the wind from the dams to the valley floor. The 14C activities indicate that groundwater is recent.

Highly efficient electrocatalytic oxidation of sterol by synergistic effect of aminoxyl radicals and SeNi5P4

AbstractThe exploration of efficient and environmentally friendly oxidation method is highly desirable to overcome the critical problems of poor selectivity and heavy metal contamination for the fine chemicals industry. Herein, a self‐supported three‐dimensional (3D) SeNi5P4 nanosheet electrocatalyst was rationally designed and fabricated. Benefiting from the synergistic effect of aminoxyl radical and mesoporous SeNi5P4/graphite felt (GF), an excellent performance of ≥98% selectivity and 33.12 kg (m−3 h−1) space–time yield was obtained for sterol intermediate oxidation with the enhanced mass transfer effect of the continuous flow system. The doping of anionic selenium and phosphorus modulated the electronic structure of SeNi5P4, and the oxyhydroxides generated by surface reconstruction accelerated the turnover of 2,2,6,6‐tetramethyl‐1‐piperidine N‐oxyl (TEMPO), thereby enhancing the intrinsic electrocatalytic activity. A scale‐up experiment was conducted with stacked‐flow electrolyzer demonstrated the application potential. This work provided an efficient synergistic electrocatalytic strategy to facilitate rapid electron and mass transfer for electrochemical alcohol oxidation and highlighted the potential for practical electrosynthesis applications.

High-Crystallinity BiOCl Nanosheets as Efficient Photocatalysts for Norfloxacin Antibiotic Degradation.

Semiconductor photocatalysts are essential materials in the field of environmental remediation. Various photocatalysts have been developed to solve the contamination problem of norfloxacin in water pollution. Among them, a crucial ternary photocatalyst, BiOCl, has attracted extensive attention due to its unique layered structure. In this work, high-crystallinity BiOCl nanosheets were prepared using a one-step hydrothermal method. The obtained BiOCl nanosheets showed good photocatalytic degradation performance, and the degradation rate of highly toxic norfloxacin using BiOCl reached 84% within 180 min. The internal structure and surface chemical state of BiOCl were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse reflectance (UV-vis), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectra (XPS), and photoelectric techniques. The higher crystallinity of BiOCl closely aligned molecules with each other, which improved the separation efficiency of photogenerated charges and showed high degradation efficiency for norfloxacin antibiotics. Furthermore, the obtained BiOCl nanosheets possess decent photocatalytic stability and recyclability.

The Development of Alginate/Ag NPs/Caffeic Acid Composite Membranes as Adsorbents for Water Purification

Since the water pollution problem still affects the environmental system and human health, the need to develop innovative membranes has become imperious. Lately, researchers have focused on developing novel materials to help diminish the contamination problem. The aim of present research was to obtain innovative adsorbent composite membranes based on a biodegradable polymer, alginate, to remove toxic pollutants. Of all pollutants, lead was chosen due to its high toxicity. The composite membranes were successfully obtained through a direct casting method. The silver nanoparticles (Ag NPs) and caffeic acid (CA) from the composite membranes were kept at low concentrations, which proved enough to bestow antimicrobial activity to the alginate membrane. The obtained composite membranes were characterised by Fourier transform infrared spectroscopy and microscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG-DSC). Swelling behaviour, lead ion (Pb2+) removal capacity, regeneration and reusability were also determined. Further, the antimicrobial activity was tested against selected pathogenic strains (S. aureus, E. faecalis sp., P. aeruginosa, E. coli and C. albicans). The presence of Ag NPs and CA improves the antimicrobial activity of the newly developed membranes. Overall, the composite membranes are suitable for complex water treatment (removal of heavy metal ions and antimicrobial treatment).

Sequestration and recovery of thorium ions using a recyclable, low-cost, glutathione-based magnetic nanocomposite: Experimental study and statistical modeling

Efficient removal and recovery of thorium from water resources is necessary to resolve the problem of radioactive contamination. To address this issue, magnetically separable Glu@MNPs have been fabricated and efficiently utilized for the removal of Th(IV). 99.40 % removal of Th(IV) by Glu@MNPs could attain an equilibrium state within 10 min at a dosage level of 6 mg for 20 ml of 50 mg/L thorium solution at pH 4 and 25 °C. It obeys Langmuir isotherm with maximum adsorption capacity of 636.94 mg g−1, which is independent of temperature variation. Kinetically, the adsorptive performance of Glu@MNPs fits well in the pseudo-second-order equation. The high removal efficiency is due to the existence of several types of functional groups on the surface of Glu@MNPs, which provide electrostatic attraction, and vander wall forces between adsorbate and adsorbent. The optimum conditions obtained from Box-Behnken composite design model was well matched with batch adsorption studies. Further, the results obtained for removal of Th(IV) by UV–vis spectroscopy matched well with ICP-OES. The removal efficiency still remained high (85.65 %) even after 10 adsorption–desorption cycles. Thus, Glu@MNPs acts as a timesaving adsorbent for sequestration of Th(IV) from an aqueous media with excellent removal performance.

Energy-Efficient Ammonia Synthesis from Nitrate via CoNi Alloys Incorporated in Carbon Frameworks

As a nitrogen-containing source, nitrate is regarded as a promising precursor for generating ammonia (NH3) through electrochemical processes that can potentially mitigate the problem of groundwater contamination and the hydrogen-carrier energy crisis. Herein, we report a cobalt zeolitic imidazolate framework (ZIF-67)-derived catalyst of CoNi alloys incorporated in N-doped carbon frameworks for nitrate electroreduction. Computational results obtained using the density functional theory give a deep insight that the structure of CoNi alloys embedded in the N-doped carbon skeleton can inhibit the production of hydrogen and facilitate the hydrogenation of *NO intermediates. The enriched active sites from the ZIF-67-derived structure and the introduction of Ni in the catalyst afford desirable electrocatalytic performance. Finally, the optimized CoNi@NC hybrid can achieve an ammonia production of 168 mmol gcat–1 h–1 and a Faradaic efficiency of ∼93% at a potential as low as −0.1 V vs reversible hydrogen electrode (RHE). The highest yield rate of 1254 mmol gcat–1 h–1 can be detected at −0.6 V vs RHE. This study can inspire further development of non-noble metal-based hybrid electrocatalysts for nitrate reduction and also anticipation into sustainable synthesis of carbon-related fuels from CO2 reduction.

Ecological risk assessment of aquatic organisms induced by heavy metals in the estuarine waters of the Pearl River

With the rapid economic development of China's coastal areas and the growth of industry and population, the problem of heavy metal contamination in estuarine waters is increasing in sensitivity and seriousness. In order to accurately and quantitatively describe the current status of heavy metal contamination and identify sensitive aquatic organisms with high ecological risks, five heavy metals in eight estuaries of the Pearl River were monitored at monthly intervals from January to December in 2020, and the ecological risks of aquatic organisms induced by heavy metals were evaluated using Risk quotients (RQ) and species sensitivity distributions (SSD) methods. The results showed that the concentrations of As, Cu, Pb, Hg and Zn in estuaries of the Pearl River were (0.65–9.25) μg/L, (0.07–11.57) μg/L, (0.05–9.09) μg/L, (< 0.40) μg/L and (0.67–86.12) μg/L, respectively. With the exception of Hg in Jiaomen water, the other heavy metals in each sampling site met or exceed the water quality standard of Grade II. The aquatic ecological risks of As, Pb and Hg were generally low in the waters of the Pearl River estuary, but individual aquatic organisms are subject to elevated ecological risks due to Cu and Zn. The content of Zn has a lethal effect on the crustaceans Temora Stylifera, and the content of Cu has a serious impact on the mollusks Corbicula Fluminea and has a certain impact on the crustaceans Corophium sp. and the fish Sparus aurata. Heavy metal levels and joint ecological risks (msPAF) in the Humen, Jiaomen, Hongqimen, and Hengmen estuaries were slightly higher than in other estuaries, and the Yamen estuary had the lowest contration of heavy metals and ecological risk. Research findings can serve as a basis for formulating water quality standards for heavy metals and for protecting aquatic biodiversity in the Pearl River Estuary.

Co-existence of polyethylene microplastics and tetracycline on soil microbial community and ARGs

Microplastics are plastic particles with particle size less than 5 mm in the environment. As an emerging organic pollutant, the presence of microplastics in the soil environment has been widely noticed. Also, due to the overuse of antibiotics, a large amount of antibiotics that cannot be fully absorbed by humans and livestock enter the soil environment in the form of urine or manure, making the soils suffer from serious antibiotic contamination problems. To address the environmental problems of microplastics and antibiotic contamination in soils, this study was conducted to investigate the effects of PE microplastics on antibiotic degradation, microbial community characteristics and ARGs in tetracycline-contaminated soils. The results showed that the addition of PE microplastics inhibited the degradation of tetracycline, and significantly increased the organic carbon content and decreased the neutral phosphatase activity. The addition of PE microplastics significantly reduced the alpha diversity of soil microbial community. Compared to the single tetracycline contamination. In addition, combined contamination with PE microplastics and tetracycline significantly affected bacterial genera such as Aeromicrobium, Rhodococcus, Mycobacterium and Intrasporangium. Metagenome sequencing studies revealed that the addition of PE microplastics inhibited the dissipation of ARGs in tetracycline-contaminated soils. There were strong positive correlations between Multidrug, Aminoglycoside and Clycopeptide resistance genes and Chloroflexi and Proteobacteria in tetracycline contaminated soils, and there was a strong positive correlation between Aminoglycoside resistance genes and Actinobacteria in combined contamination of PE microplastics and tetracycline. This study will provide some data support for the current environmental risk assessment of the coexistence of multiple contaminants in soil.

The big three: Accuracy, organization, and retrieval effects of latent semantic attributes.

Rating norms for semantic attributes (e.g., concreteness, dominance, familiarity, and valence) are widely used in many psychological literatures to study the effects of processing specific types of semantic content. Word and picture norms for many attributes are available for thousands of items, but there is a contamination problem in experimentation. When an attribute's ratings are varied, how the semantic content that people process changes is unclear because ratings of individual attributes are correlated with ratings of so many other attributes. To solve this problem, the psychological space that 20 attributes occupy has been mapped, and factor score norms have been published for the latent attributes that generate that space (emotional valence, age-of-acquisition, and symbolic size). These latent attributes have yet to be manipulated in experimentation, and hence, their effects are unknown. We conducted a series of experiments that focused on whether they affect accuracy, memory organization, and specific retrieval processes. We found that (a) all three latent attributes affected recall accuracy, (b) all three affected memory organization in recall protocols, and (c) all three affected direct verbatim access, rather than reconstruction or familiarity. The memory effects of two of them (valence and age-of-acquisition) were unconditional, but memory effects were only detected for the third at particular levels of the other two. The key implications are that semantic attributes can now be cleanly manipulated, and when they are, they have broad downstream effects on memory. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Subspace-Based Pilot Decontamination in User-Centric Scalable Cell-Free Wireless Networks

We consider a cell-free wireless system operated in Time Division Duplex (TDD) mode with user-centric clusters of remote radio units (RUs). Since the uplink pilot dimensions per channel coherence slot is limited, co-pilot users might incur mutual pilot contamination. In the current literature, it is assumed that the long-term statistical knowledge of all user channels is available. This enables Minimum Mean-Square Error channel estimation or simplified dominant subspace projection, which achieves significant pilot decontamination under certain assumptions on the channel covariance matrices. However, estimating the channel covariance matrix or even just its dominant subspace at all RUs forming a user cluster is not an easy task. In fact, if not properly designed, a piloting scheme for such long-term statistics estimation will also be subject to the contamination problem. In this paper, we propose a new channel subspace estimation scheme explicitly designed for cell-free wireless networks. Our scheme is based on 1) a sounding reference signal (SRS) using latin squares wideband frequency hopping, and 2) a subspace estimation method based on robust Principal Component Analysis (R-PCA). The SRS hopping scheme ensures that for any user and any RU participating in its cluster, only a few pilot measurements will contain strong co-pilot interference. These few heavily contaminated measurements are (implicitly) eliminated by R-PCA, which is designed to regularize the estimation and discount the “outlier” measurements. Our simulation results show that the proposed scheme achieves almost perfect subspace knowledge, which in turns yields system performance very close to that with ideal channel state information, thus essentially solving the problem of pilot contamination in cell-free user-centric TDD wireless networks.

Individual Risk Assessment for Population Living on the Territories Long-Term Polluted by Organochlorine Pesticides

The long-term storage of unutilized pesticides raised new problems of long-term environmental contamination. The study presents the results of surveying 151 individuals in 7 villages living close to pesticide-contaminated localities. All individuals have been surveyed concerning their consumption habits and lifestyle characteristics. An assessment of the general exposure risks of the local population was carried out using the analysis of pollutants in food products and the average levels of their consumption in the region. The cohort risk evaluation revealed that the greatest risk was associated with the regular consumption of cucumbers, pears, bell peppers, meat, and milk. The new model to estimate individual risks of long-term pesticide pollution was proposed as a calculation of the combined action of 9 risk factors, including individual genotypes, age, lifestyle, and personal pesticide consumption rates. The analysis of the predictive ability of this model showed that the final score for individual health risks corresponded to the development of chronic diseases. A high level of chromosomal aberrations was evidenced for individual genetic risk manifestations. The combined influence of all risk factors revealed contributions of 24.7% for health status and 14.2% for genetic status, while other impacts go to all unaccounted factors.

Eliminating carbon contamination with improved one-step electrochemical preparation of refractory high-entropy alloy TiZrHfNbTa

Creating refractory high-entropy alloys (RHEAs) effectively without impurities is a momentous challenge. Conventional methods for the preparation of RHEAs have exacting requirements for raw material purity and energy consumption. Molten salt electrolytic oxides are applied to the preparation of HEAs by virtue of their low cost and high efficiency. However, the use of graphite anodes in electrolysis will result in the carbon contamination of the products due to the deposition of CO32− at the cathode. Increasing the reaction temperature accelerates the deoxidation of the oxide, thus reducing the amount of carbide but not eliminating it. Switching HfH2 instead of HfO2 and using Nb2O5 to shield the precursor can effectively remove carbon contamination. However, this leads to a complicated preparation process and energy waste. Herein, we use the solid oxygen ion-conducting membrane (SOM) containing graphite and Sn (named as SOM@C/Sn) anode to separate the carbon from the molten salt and prevent the circulation of CO32−. The pure single-phase TiZrHfNbTa RHEA can be produced in only one-step with the SOM@C/Sn anode, which completely solves the problem of carbon contamination in the molten salt electrolysis preparation of HEAs. This work provides a feasible solution for the preparation of novel complex alloys such as carbon-free RHEAs in a low-cost short process.

USING OF THE MATHEMATICAL PLANNING OF THE EXPERIMENT FOR THE QUANTITATIVE ASSESSMENT OF THE METHOD OF PHYTOREMEDIATION RESTORATION OF SOILS CONTAMINATED WITH PETROCHEMICALS

Nowadays, the problem of soil contamination with oil products has global character. The issue of soil quality is particularly acute in technogenically loaded territories, which, in particular, include the territories of airports. To reduce the negative impact of petrochemicals on the condition of the soils and to restore their quality characteristics, various methods of destruction of petroleum hydrocarbons in contaminated soils are used. In recent years, biological methods of cleaning soils from oil products are gaining more and more popularity. These methods have a number of advantages over physic-chemical and mechanical methods of restoring the quality of the soils contaminated with petrochemicals. However, the most popular is the phytoremediation method. In our research, we have chosen this method of cleaning soils contaminated with aviation fuel, as it is one of the most ecologically safe, cost-effective, accessible and promising of the existing methods of restoring the quality of soils contaminated with petroleum products. The purpose of the work was to evaluate the use of phytoremediation to restore the quality characteristics of soil contaminated with aviation fuel, using the method of mathematical planning of the experiment, namely the method of full factorial experiment, which allows obtaining a statistical model of the influence of the factors involved, namely the presence of plants and petroleum products. To achieve the goal, the phytoremediation technology of soil samples artificially contaminated with TS-1 aviation kerosene was applied. The plants chosen for the study were oats (Avena Sativa L.) and timothy (Phleum L.). The change in the level of phytotoxicity of the soil samples after the application of phytoremediation technology was determined using a growth test with watercress (Lepidium sativum).&#x0D; The obtained data showed that on the 10th day of observation, the negative impact of aviation fuel (X2) and the positive impact of plants (X1) is observed. At the same time, strengthening the positive impact of plant action and reducing the negative impact of aviation fuel in the interaction of these two factors X1 and X2. Analyzing the obtained results, we can draw a conclusion about the possibility of using the technology of phytoremediation of oil-contaminated soils, which is quantitatively evaluated using the method of a full factorial experiment.

Tn5 Transposon-based Mutagenesis for Engineering Phage-resistant Strains ofEscherichia coliBL21 (DE3).

Escherichia coli is a preferred strain for recombinant protein production, however, it is often plagued by phage infection during experimental studies and industrial fermentation. While the existing methods of obtaining phage-resistant strains by natural mutation are not efficient enough and time-consuming. Herein, a high-throughput method by combining Tn5 transposon mutation and phage screening was used to produce Escherichia coli BL21 (DE3) phage-resistant strains. Mutant strains PR281-7, PR338-8, PR339-3, PR340-8, and PR347-9 were obtained, and they could effectively resist phage infection. Meanwhile, they had good growth ability, did not contain pseudolysogenic strains, and were controllable. The resultant phage-resistant strains maintained the capabilities of producing recombinant proteins since no difference in mCherry red fluorescent protein expression was found in phage-resistant strains. Comparative genomics showed that PR281-7, PR338-8, PR339-3, and PR340-8 mutated in ecpE, nohD, nrdR, and livM genes, respectively. In this work, a strategy was successfully developed to obtain phage-resistant strains with excellent protein expression characteristics by Tn5 transposon mutation. This study provides a new reference to solve the phage contamination problem.