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Hexabromocyclododecane (HBCD) is a widely used brominated flame retardant; however, it is a persistent organic pollutant as well as affects the human thyroid hormones and causes cancer. However, the degradation of HBCD has received little attention from researchers. Due to its bioaccumulative and hazardous properties, an appropriate strategy for its remediation is required. In this study, we investigated the biodegradation of HBCD using Shewanella oneidensis MR-1 under optimized conditions. The Box-Behnken design (BBD) was implemented for the optimization of the physical degradation parameters of HBCD. S. oneidensis MR-1 showed the best degradation performance at a temperature of 30 °C, pH 7, and agitation speed of 115 rpm, with an HBCD concentration of 1125 µg/L in mineral salt medium (MSM). The strain tolerated up to 2000 µg/L HBCD. Gas chromatography-mass spectrometry analysis identified three intermediates, including 2-bromo dodecane, 2,7,10-trimethyldodecane, and 4-methyl-1-decene. The results provide an insightful understanding of the biodegradation of HBCD by S. oneidensis MR-1 under optimized conditions and could pave the way for further eco-friendly applications. KEY POINTS: ⢠HBCD biodegradation by Shewanella oneidensis ⢠Optimization of HBCD biodegradation by the Box-Behnken analysis ⢠Identification of useful metabolites from HBCD degradation.
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Retardadores de Chama , Hidrocarbonetos Bromados , Shewanella , Humanos , Biodegradação Ambiental , Hidrocarbonetos Bromados/química , Hidrocarbonetos Bromados/metabolismo , Shewanella/metabolismo , Retardadores de Chama/metabolismoRESUMO
Due to the limited resources and environmental problems associated with fossil fuels, there is a growing interest in utilizing renewable resources for the production of biofuels through microbial fermentation. Isobutanol is a promising biofuel that could potentially replace gasoline. However, its production efficiency is currently limited by the use of naturally isolated microorganisms. These naturally isolated microorganisms often encounter problems such as a limited range of substrates, low tolerance to solvents or inhibitors, feedback inhibition, and an imbalanced redox state. This makes it difficult to improve their production efficiency through traditional process optimization methods. Fortunately, recent advancements in genetic engineering technologies have made it possible to enhance microbial hosts for the increased production of isobutanol from renewable resources. This review provides a summary of the strategies and synthetic biology approaches that have been employed in the past few years to improve naturally isolated or non-natural microbial hosts for the enhanced production of isobutanol by utilizing different renewable resources. Furthermore, it also discusses the challenges that are faced by engineered microbial hosts and presents future perspectives to enhancing isobutanol production. KEY POINTS: ⢠Promising potential of isobutanol to replace gasoline ⢠Engineering of native and non-native microbial host for isobutanol production ⢠Challenges and opportunities for enhanced isobutanol production.
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Biocombustíveis , Gasolina , Butanóis , Clonagem MolecularRESUMO
Objective: To evaluate the awareness, attitude and knowledge of cardiopulmonary resuscitation (CPR) among university-enrolled medical and non-medical undergraduate students of Pakistan. Methods: Cross-sectional online survey-based study was conducted across institutes in Pakistan from December, 2022 to January, 2023. The study involved university-enrolled undergraduate students across the country. The structured questionnaire was disseminated via Google forms. For statistical analysis, SPSS version 20 was used to analyze the data by applying independent sample t-tests and ANOVA. Results: A total of 249 responses were received. After the exclusion of two responses, the overall awareness score of participants was found to be 2.49 ± 1.33, attitude score of 4.09 ± 1.74, and knowledge score of 3.51 ± 2.13. Female respondents, medical students, unmarried (single), private institutes, and respondents with educated parents achieved relatively higher scores. The overall difference in awareness scores among different regions of Pakistan was also significant (p <0.05). Gender, region, and parental literacy rate also showed effects on participants' basic life support (BLS) and CPR knowledge (p <0.05). Conclusions: Overall knowledge and awareness were unsatisfactory and inadequate in university-enrolled undergraduate students, with no one getting a complete score on very basic knowledge questions. Significant differences in awareness, attitude, and knowledge among different regions, genders, and parental literacy rates were found.
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Phenol accounts for a large proportion of the contamination in industrial wastewater discharged from chemical plants due to its wide use as a raw chemical. Residual phenol waste in water and soil significantly endangers human health and the natural environment. In this study, an Acinetobacter radioresistens strain, APH1, was isolated and identified for its efficient capability of utilizing phenol as sole carbon source for growth. A draft genome sequence containing 3,290,330 bases with 45 contigs was obtained, and 22 genes were found to be involved in phenol metabolism and 51 putative drug-resistance genes were annotated by genomic analysis. The optimal conditions for cell culture and phenol removal were determined to be 30 °C, pH 6.0, and a phenol concentration of 500 mg/L; the upper limit of phenol tolerance was 950 mg/L. Based on GC-MS analysis, the key metabolites including cis,cis-muconic acid, catechol, and succinic acid were detected. During bioremediation experiment using 450 mg/kg (dry weight) of phenol-contaminated soil, the strain APH1 removed 99% of the phenol within 3 days. According to microbial diversity analysis, the microbial abundance of Chungangia, Bacillus, Nitrospira, Lysinibacillus, and Planomicrobium increased after the addition of phenol. Furthermore, at day 23, the abundance of strain APH1 was greatly reduced, and the microbial diversity and structure of the whole microbial community were gradually recovered, indicating that strain APH1 would not affect this microbial ecosystem. These findings provide insights into the bioremediation of soil contaminated with phenol.
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Acinetobacter/metabolismo , Carbono/metabolismo , Fenol/metabolismo , Microbiologia do Solo , Solo/química , Acinetobacter/genética , Biodegradação Ambiental , Variação Genética , Genoma Bacteriano , Concentração de Íons de Hidrogênio , Águas Residuárias/químicaRESUMO
Due to large spectral efficiency and low power consumption, the Massive Multiple-Input-Multiple-Output (MIMO) became a promising technology for the 5G system. However, pilot contamination (PC) limits the performance of massive MIMO systems. Therefore, two pilot scheduling schemes (i.e., Fractional Pilot Reuse (FPR) and asynchronous fractional pilot scheduling scheme (AFPS)) are proposed, which significantly mitigated the PC in the uplink time division duplex (TDD) massive MIMO system. In the FPR scheme, all the users are distributed into the central cell and edge cell users depending upon their signal to interference plus noise ratio (SINR). Further, the capacity of central and edge users is derived in terms of sum-rate, and the ideal number of the pilot is calculated which significantly maximized the sum rate. In the proposed AFPS scheme, the users are grouped into central users and edge users depending upon the interference they receive. The central users are assigned the same set of pilots because these users are less affected by interference, while the edge users are assigned the orthogonal pilots because these users are severely affected by interference. Consequently, the pilot overhead is reduced and inter-cell interference (ICI) is minimized. Further, results verify that the proposed schemes outperform the previous proposed traditional schemes, in terms of improved sum rates.
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Quality of service (QoS)-aware data gathering in static-channel based underwater wireless sensor networks (UWSNs) is severely limited due to location and time-dependent acoustic channel communication characteristics. This paper proposes a novel cross-layer QoS-aware multichannel routing protocol called QoSRP for the internet of UWSNs-based time-critical marine monitoring applications. The proposed QoSRP scheme considers the unique characteristics of the acoustic communication in highly dynamic network topology during gathering and relaying events data towards the sink. The proposed QoSRP scheme during the time-critical events data-gathering process employs three basic mechanisms, namely underwater channel detection (UWCD), underwater channel assignment (UWCA) and underwater packets forwarding (UWPF). The UWCD mechanism finds the vacant channels with a high probability of detection and low probability of missed detection and false alarms. The UWCA scheme assigns high data rates channels to acoustic sensor nodes (ASNs) with longer idle probability in a robust manner. Lastly, the UWPF mechanism during conveying information avoids congestion, data path loops and balances the data traffic load in UWSNs. The QoSRP scheme is validated through extensive simulations conducted by NS2 and AquaSim 2.0 in underwater environments (UWEs). The simulation results reveal that the QoSRP protocol performs better compared to existing routing schemes in UWSNs.
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The phytochemical screening, antimicrobial, antioxidant and cytotoxic properties of Camellia sinensis were evaluated in the present study. The phytochemical screening revealed the presence of an applicable amount of lycopene, ß-carotenes, flavonoids and tannins in C. sinensis. Among the phytochemicals, tannin was found to be significantly higher in tea plant. The antimicrobial activity of plant extracts against selected bacterial strains namely, Escherichia coli, Staphylococcus aurous, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Marginella morganii and Haemophilus influenzae was investigated. The results showed that the stem part of C. sinensis presented greater antimicrobial potential than the leaf and root. Antioxidant activity (assessed through % inhibition of linoleic acid per oxidation test) was the highest (89.22%) in n-hexane extract of root part as compared to other extracts. Finally, the cytotoxicity analysis (haemolytic activity against human erythrocytes) of plant extract showed the negligible (%) lysis of RBCs ranging from 1.73 to 4.01%. In conclusion, it can be suggested that C. sinensis is the potential source to obtain bioactive phenolic compounds with high antimicrobial and antioxidant properties, which could possibly be exploited for the treatment of various infectious diseases.
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Anti-Infecciosos/farmacologia , Antioxidantes/farmacologia , Camellia sinensis/química , Extratos Vegetais/farmacologia , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/toxicidade , Antioxidantes/isolamento & purificação , Antioxidantes/toxicidade , Células Cultivadas , Eritrócitos/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Humanos , Ácido Linoleico/química , Oxirredução , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/toxicidade , Folhas de Planta/química , Raízes de Plantas/química , Caules de Planta/química , Solventes/químicaRESUMO
A three-dimensional (3D) macroporous reduced graphene oxide/polypyrrole (rGO/Ppy) hydrogel assembled by bacterial cells was fabricated and applied for microbial fuel cells. By taking the advantage of electroactive cell-induced bioreduction of graphene oxide and in-situ polymerization of Ppy, a facile self-assembly by Shewanella oneidensis MR-1and in-situ polymerization approach for 3D rGO/Ppy hydrogel preparation was developed. This facile one-step self-assembly process enabled the embedding of living electroactive cells inside the hydrogel electrode, which showed an interconnected 3D macroporous structures with high conductivity and biocompatibility. Electrochemical analysis indicated that the self-assembly of cell-embedding rGO/Ppy hydrogel enhanced the electrochemical activity of the bioelectrode and reduced the electron charge transfer resistance between the cells and the electrode. Impressively, extremely high power output of 3366 ± 42 mW m-2 was achieved from the MFC with cell-embedding rGO/Ppy hydrogel rGO/Ppy, which was 8.6 times of that delivered from the MFC with bare electrode. Further analysis indicated that the increased cell loading by the hydrogel and improved electrochemical activity by the rGO/Ppy composite would be the underlying mechanism for this performance improvement. This study provided a facile approach to fabricate the biocompatible and electrochemical active 3D nanocomposites for MFC, which would also be promising for performance optimization of various bioelectrochemical systems.
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Fontes de Energia Bioelétrica , Fontes de Energia Bioelétrica/microbiologia , Polímeros/química , Pirróis/química , Hidrogéis , EletrodosRESUMO
BACKGROUND: While representing a model bacterium and one of the most used chassis in biomanufacturing, performance of Escherichia coli is often limited by severe stresses. A super-robust E. coli chassis that could efficiently tolerant multiple severe stresses is thus highly desirable. Sterols represent a featured composition that distinguishes eukaryotes from bacteria and all archaea, and play a critical role in maintaining the membrane integrity of eukaryotes. All sterols found in nature are directly synthesized from (S)-2,3-oxidosqualene. However, in E. coli, (S)-2,3-oxidosqualene is not present. RESULTS: In this study, we sought to introduce (S)-2,3-oxidosqualene into E. coli. By mining and recruiting heterologous enzymes and activation of endogenous pathway, the ability of E. coli to synthesize (S)-2,3-oxidosqualene was demonstrated. Further analysis revealed that this non-native chemical confers E. coli with a robust and stable cell membrane, consistent with a figurative analogy of wearing an "Iron Man's armor"-like suit. The obtained Iron Man E. coli (IME) exhibited improved tolerance to multiple severe stresses, including high temperature, low pH, high salt, high sugar and reactive oxygen species (ROS). In particular, the IME strain shifted its optimal growth temperature from 37 °C to 42-45 °C, which represents the most heat-resistant E. coli to the best of our knowledge. Intriguingly, this non-native chemical also improved E. coli tolerance to a variety of toxic feedstocks, inhibitory products, as well as elevated synthetic capacities of inhibitory chemicals (e.g., 3-hydroxypropionate and fatty acids) due to improved products tolerance. More importantly, the IME strain was effectively inhibited by the most commonly used antibiotics and showed no undesirable drug resistance. CONCLUSIONS: Introduction of the non-native (S)-2,3-oxidosqualene membrane lipid enabled E. coli to improve tolerance to various stresses. This study demonstrated the effectiveness of introducing eukaryotes-featured compound into bacteria for enhancing overall tolerance and chemical production.
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Cancer is among the major public health problems as well as a burden for Pakistan. About 148,000 new patients are diagnosed with cancer each year, and almost 100,000 patients die due to this fatal disease. Lung, breast, liver, cervical, blood/bone marrow, and oral cancers are the most common cancers in Pakistan. Perhaps smoking, physical inactivity, infections, exposure to toxins, and unhealthy diet are the main factors responsible for the spread of cancer. We preferred a novel four-component mixture model under Bayesian estimation to estimate the average number of incidences and death of both genders in different age groups. For this purpose, we considered 28 different kinds of cancers diagnosed in recent years. Data of registered patients all over Pakistan in the year 2012 were taken from GLOBOCAN. All the patients were divided into 4 age groups and also split based on genders to be applied to the proposed mixture model. Bayesian analysis is performed on the data using a four-component exponential mixture model. Estimators for mixture model parameters are derived under Bayesian procedures using three different priors and two loss functions. Simulation study and graphical representation for the estimates are also presented. It is noted from analysis of real data that the Bayes estimates under LINEX loss assuming Jeffreys' prior is more efficient for the no. of incidences in male and female. As far as no. of deaths are concerned again, LINEX loss assuming Jeffreys' prior gives better results for the male population, but for the female population, the best loss function is SELF assuming Jeffreys' prior.
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Teorema de Bayes , Neoplasias/epidemiologia , Biologia Computacional , Simulação por Computador , Modelos Epidemiológicos , Feminino , Humanos , Incidência , Funções Verossimilhança , Masculino , Modelos Estatísticos , Neoplasias/mortalidade , Paquistão/epidemiologiaRESUMO
Hexabromocyclododecanes (HBCDs) are the second-most widely used brominated flame retardants. They cause inappropriate antidiuretic hormone syndrome and can induce cancer. However, little information is available about bacterial degradation of HBCDs. In this study, HBCDs (α-, ß- and γ-HBCD) degrading strain Pseudomonas aeruginosa HS9 was isolated, identified, and characterized. The strain HS9 could remove 69% (± 0.05%) of 1.7 mg/L HBCDs in 14 days. Based on identification of metabolites, this bacterium could oxidize HBCDs by two pathways. In the first, HBCDs are sequentially debromized to tetrabromocyclododecene, dibromocyclododecadiene, and then debromized once more to cis, trans, trans-1, 5, 9-cyclododecatriene (CDT). After that, CDT is then oxidized to 1,2-epoxy-5,9-cyclododecadiene. The second identified pathway is a simultaneous debrominating and hydroxylating process based on the detection of 2,5,6,9,10-pentabromocyclododecanols, which were newly identified. The strain's effects on plant-maize growth were tested and bioremediation evaluation trials were performed. The addition of strain HS9 could decrease HBCDs of 4.08 mg/g (87.6% removed) and 0.1 mg/g (25% removed) in soil and plants, respectively. Microbial diversity analysis shows that the addition of strain HS9 can promote the abundance of plant-beneficial bacteria, such as Methylobacillus, Nitrosomonas, Plancoccus, Bacillus, and Rhodococcus. The results provide insights for the bioremediation of HBCDs-contaminated soils.
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Biodegradação Ambiental , Retardadores de Chama/metabolismo , Hidrocarbonetos Bromados/metabolismo , Pseudomonas/metabolismo , Poluentes do Solo/metabolismo , Zea mays/metabolismoRESUMO
Dibenzofuran (DBF) derivatives have caused serious environmental problems, especially those produced by paper pulp bleaching and incineration processes. Prominent for its resilient mutagenicity and toxicity, DBF poses a major challenge to human health. In the present study, a new strain of Pseudomonas aeruginosa, FA-HZ1, with high DBF-degrading activity was isolated and identified. The determined optimum conditions for cell growth of strain FA-HZ1 were a temperature of 30⯰C, pH 5.0, rotation rate of 200â¯rpm and 0.1â¯mM DBF as a carbon source. The biochemical and physiological features as well as usage of different carbon sources by FA-HZ1 were studied. The new strain was positive for arginine double hydrolase, gelatinase and citric acid, while it was negative for urease and lysine decarboxylase. It could utilize citric acid as its sole carbon source, but was negative for indole and H2S production. Intermediates of DBF 1,2-dihydroxy-1,2-dihydrodibenzofuran, 1,2-dihydroxydibenzofuran, 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, 2,3-dihydroxybenzofuran, 2-oxo-2-(2'-hydrophenyl)lactic acid, and 2-hydroxy-2-(2'-hydroxyphenyl)acetic acid were detected and identified through liquid chromatography-mass analyses. FA-HZ1 metabolizes DBF by both the angular and lateral dioxygenation pathways. The genomic study identified 158 genes that were involved in the catabolism of aromatic compounds. To identify the key genes responsible for DBF degradation, a proteomic study was performed. A total of 1459 proteins were identified in strain FA-HZ1, of which 100 were up-regulated and 104 were down-regulated. A novel enzyme "HZ6359 dioxygenase", was amplified and expressed in pET-28a in E. coli BL21(DE3). The recombinant plasmid was successfully constructed, and was used for further experiments to verify its function. In addition, the strain FA-HZ1 can also degrade halogenated analogues such as 2, 8-dibromo dibenzofuran and 4-(4-bromophenyl) dibenzofuran. Undoubtedly, the isolation and characterization of new strain and the designed pathways is significant, as it could lead to the development of cost-effective and alternative remediation strategies. The degradation pathway of DBF by P. aeruginosa FA-HZ1 is a promising tool of biotechnological and environmental significance.
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Benzofuranos/metabolismo , Poluentes Ambientais/metabolismo , Pseudomonas aeruginosa/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Dioxigenases/genética , Dioxigenases/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Resíduos Industriais , Redes e Vias Metabólicas/genética , Proteômica , Pseudomonas aeruginosa/química , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/crescimento & desenvolvimentoRESUMO
Environmental pollution caused by the release of industrial chemicals is currently one of the most important environmental harms. Manufacturing chemicals can be biodegraded, and valuable intermediates can be used as pharmacophores in drug targeting and have several other useful purposes. Hexabromocyclododecane (HBCD), a non-aromatic brominated flame retardant, is a toxic compound that consists of a cycloaliphatic ring of 12 carbon atoms to which six bromine atoms are attached. It is formed by bromination of cis-trans-trans-1,5,9-cyclododecatriene, but its use is now restricted in several countries, because it is an environmental pollutant. Little is known about whether bacteria can degrade HBCD. A bacterial strain that degrades HBCD was recently isolated using enrichment culture techniques. Based on morphological, biochemical and phylogenetic analysis this isolate was categorized as Bacillus cereus and named strain HBCD-sjtu. Maximum growth and HBCD-degrading activity were observed when this strain was grown at 30 °C, pH 7.0 and 200 RPM in mineral salt medium containing 0.5 mm HBCD. The genome of strain HBCD-sjtu, which consists of only one circular chromosome, was sequenced. This whole genome sequence will be crucial for illuminating the molecular mechanisms of HBCD degradation.