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1.
Environ Sci Pollut Res Int ; 30(31): 77593-77604, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37261683

RESUMO

The current global greenhouse gas (GHG) emission rates will increase the average global temperature by 1.5 °C by 2050. This will be detrimental for organisms and ecosystems, as well as human well-being. Many countries have pledged to halve their emissions by 2030 and reach net zero targets by 2050. Optimum generation of electricity from sustainable green sources and its use to charge electric vehicle (EV) batteries will solve this problem to greater extent. The best places to capture solar energy, use it to meet load demand and charge EV batteries are the large open car parking areas near retail stores, academic institutes, industrial areas, and offices. This study targets the open parking areas of an academic campus (King Saud University, Riyadh) to meet the load demand of 25,000 kWh/day with a peak load of 4180 kW and charging the batteries of parked EVs. Four system designs, simple grid, standalone photovoltaic (PV), simple grid and PV, and smart grid and PV, are compared. Currently, the cost of energy (COE) of the grid is US $ 0.085 in KSA. In comparison, the COE of standalone PV is almost 4.5 folds higher and in simple grid with PV, it is around 58% higher. However, a renewable penetration of 53.8% is achieved. In the third option, smart grid with PV, the COE is 24% lower compared to the base case. A 54.3% of the total energy produced is sold back to the grid, and the total renewable penetration of 77.7% is achieved. To observe the effect of energy sale limit on project parameters, the sensitivity analysis is performed. It can be observed that with a 1 MW increase in the limit, the COE decreases by around 20% and net present cost (NPC) by around 6%. The proposed models for the solar car parks can be used elsewhere with similar climatic conditions.


Assuntos
Biodiversidade , Gases de Efeito Estufa , Humanos , Ecossistema , Temperatura , Eletricidade
2.
J Microbiol Methods ; 208: 106709, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37015313

RESUMO

The poultry industry in developing countries is still combating mortality and economic loss due to Salmonella contamination. Salmonella Gallinarum is a common pathogen of poultry birds, being the etiologic agent of fowl typhoid, which specifically infects adult birds via the oral-fecal route. Timely detection of S. Gallinarum in poultry flocks can allow early treatment intervention leading to a decrease in economic losses. Detection of S. Gallinarum is challenging, while its PCR-based detection is a promising strategy, however, due to its high genomic similarity with other commonly existing Salmonella spp., identification of S. Gallinarum from poultry samples with high specificity is still a challenge. The current study was conducted to isolate S. Gallinarum from different districts of Pakistan, assess their antibiotic susceptibility profile, and develop a method for its early detection. A total of 20 strains were isolated using buffer peptone water, selenite cysteine broth, and Xylose Lysine Tergitol-4 (XLT-4) agar supplemented with tergitol and characterized by biochemical procedures. The antibiotic sensitivity profile highlighted the highest resistance of isolates towards novobiocin and nalidixic acid, commonly used antibiotics in Pakistan Poultry production. The primers designed to amplify a unique genomic region of S. Gallinarum, showed successful detection of twenty S. Gallinarum strains, while no amplification with genomic DNA from other common Salmonella spp. The reported method can be utilized to detect S. Gallinarum from tissue samples of infected birds in a short time leading to early diagnosis and timely treatment intervention.


Assuntos
Doenças das Aves Domésticas , Salmonelose Animal , Animais , Aves Domésticas , Paquistão , Poloxaleno , Doenças das Aves Domésticas/diagnóstico , Salmonella/genética , Aves , Reação em Cadeia da Polimerase/veterinária , Resistência Microbiana a Medicamentos , Antibacterianos/farmacologia , Diagnóstico Precoce , Salmonelose Animal/diagnóstico , Galinhas
3.
Virus Res ; 329: 199107, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36996938

RESUMO

Klebsiella pneumoniae is an opportunistic pathogen responsible for nearly one-third of all Gram-negative infections. Increasing antibiotic resistance has pushed scientists to look for alternative therapeutics. Bacteriophages have emerged as one of the promising alternatives. In the current study, the Klebsiella phage JKP2 was isolated from a sewage sample and characterized against the K-17 serotype of K. pneumoniae. It produced bulls-eye-shaped clear plaques and has a latent period of 45 min with a burst size of 70 pfu/cell. It remained stable at tested pH (5 to 10) and temperatures (37 to 60 °C). Its optimum temperature for long-term storage is 4 °C and -80 °C. The JKP2 showed its infectivity against the K. pneumoniae K-17 serotype only. It controlled planktonic cells of K. pneumoniae 12 h post-incubation. At MOI-1, it efficiently eliminated 98% of 24 and 96% of 48-hour-old biofilm and 86% and 82% of mature biofilm of day 3 and 4, respectively. The JKP2 has an icosahedral capsid of 54 ± 0.5 nm with a short, non-contractile tail, measuring 12 ± 0.2 nm. It possesses a double-stranded DNA genome of 43.2 kbp with 54.1% GC content and encodes 54 proteins, including 29 with known functions and 25 with unknown functions. JKP2 was classified as Drulisvirus within the Autographiviridae family. It uses a T7-like direct terminal repeat strategy for genome packaging. JKP2 can be applied safely for therapeutic purposes as it does not encode an integrase or repressor genes, antibiotic resistance genes, bacterial virulence factors, and mycotoxins.


Assuntos
Bacteriófagos , Caudovirales , Bacteriófagos/genética , Klebsiella/genética , Sorogrupo , Klebsiella pneumoniae , Biofilmes
4.
Environ Sci Pollut Res Int ; 30(44): 99147-99159, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36279064

RESUMO

To combat the adverse environmental effects of fossil fuel burning for power generation and to conserve it for strategic use, new, clean, and renewable energy sources are being utilized for power generation. The study presents techno-economic analysis of a grid-connected solar photovoltaic (PV) power plant to partially meet the energy consumption of the people of Kuttiady village in Kerala, India. The proposed 2315.5 kW installed capacity PV is found to be feasible for the village and can produce 3878.3 MWh of energy annually while the demand is 4044.86 MWh at a plant capacity factor of 19.1% and cost of energy of 290.73 $/MWh. The performance of the proposed PV plant measured in terms of final yield (4.59 h), reference yield (5.64 h), and performance ratio (82%) is compatible and even higher with many such plants in India and other countries. Economic sensitivity analysis is also performed by varying the interest, discount, and inflation rates to check their effect on cost of energy, benefit cost ratio, and payback period. As the interest and discount rates decrease, the cost of energy and payback period also decreases while benefit cost ratio increases. The proposed plant can help in avoiding around 785 tons of greenhouse gases entering the local atmosphere of the Kuttiady village.


Assuntos
Energia Solar , Humanos , Clima , Índia
5.
Microsc Res Tech ; 85(10): 3397-3410, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35796298

RESUMO

In this study, 34 species belonging to the class Nostocophyceae order Nostocales and family Oscillatoriaceae were identified based on light microscopy (LM) and scanning electron microscopy (SEM). All species belong to nine genera of which two species belong to Arthrospira, six species to Lyngbya, ten species belongs to Oscillatoria, six species belong to Spirulina, seven species to Phormidium, three species to Microcoleus. The morpho-anatomical characters were identified among different species using LM and SEM. These studies highlighted that north-eastern area of Punjab was blessed with the diversity of algae. These outcomes also indicated that for internal examination along with LM, SEM was necessary for correct identification of algal sample up to specie level. RESEARCH HIGHLIGHTS: The different Oscillatoria species abundance in waste-water of four different areas. The sampling was carried out randomly in different seasons from the water bodies especially from waste-water. The morpho-anatomical characters were recognized using light microscopy (LM) and scanning electron microscopy (SEM). Thirty-four species belonging to the class Nostocophyceae order Nostocales and family Oscillatoriaceae were identified based on LM and SEM.


Assuntos
Pólen , Água , Microscopia Eletrônica de Varredura , Paquistão
6.
Infect Disord Drug Targets ; 22(5): e030322201654, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35240967

RESUMO

BACKGROUND: Hepatitis C viral (HCV) infection is a major clinical burden globally. Pegylated IFN-α-2a (PEG-IFN-α-2a) with ribavirin (RIB) therapy induces an array of cellular antiviral responses, including dsRNA kinases (PKR), chemokines, and cytokines to tackle the HCV infection. However, many HCV patients develop resistance to PEG-IFN/RIB therapy rendering the therapy ineffective. OBJECTIVES: Here, we assess the significance of chemokines in response to PEG-IFN-α-2a with ribavirin (PEG-IFN/RIB) therapy. METHODS: Twenty patients with HCV infection and ten healthy controls were enrolled in this study and patients were categorized into two groups 1), HCV-Responder (HCV-R), and 2) HCV-non-responder (HCV-NR). We analyzed IP-10, MIG, MCP-1, EOTAXIN, RANTES, IL-8, MIP-1a, and MIP-1b by a magnetic bead-based multiplex immunoassay approach based on Luminex X-MAP multiplex technology, using a MAGPIX instrument (Luminex Corporation, USA). RESULTS: A significant elevation of ALT and AST enzymes was observed in HCV-NR. Besides, the PEG-IFN/RIB therapy in both MIG and MCP-1 in HCV-NR patients was significantly induced. PEGIFN/ RIB therapy significantly increased the levels of chemokines, such as IL-8, IP-10, EOTAXIN, MIG, RANTES, and MIP-1ß, in HCV-R, indicating the chemokine response to PEG-IFN/RIB therapy. CONCLUSION: Hence, MCP-1 and MIG could be the potential biomarkers in HCV-NR and might be associated with the development of liver fibrosis, liver failure, and hepatocellular carcinoma. LIMITATIONS: Our study has only twenty samples of PEG-IFN/RIB treated HCV patients. This might be the reason for the lack of association between some of the inflammatory markers evaluated and the SVR, therefore, the association found between the chemokine levels observed in the plasma of HCV-R and HCV-NR and EVR cannot be extrapolated to patients infected with other HCV genotypes.


Assuntos
Antivirais , Hepatite C Crônica , Ribavirina , Antivirais/uso terapêutico , Biomarcadores , Quimiocina CCL5/sangue , Quimiocina CXCL10/sangue , Quimioterapia Combinada , Genótipo , Hepatite C Crônica/tratamento farmacológico , Humanos , Interferon alfa-2/uso terapêutico , Interleucina-8/sangue , Polietilenoglicóis , Prognóstico , Proteínas Recombinantes/uso terapêutico , Ribavirina/uso terapêutico , Resultado do Tratamento
7.
Environ Sci Pollut Res Int ; 29(57): 85842-85854, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33945095

RESUMO

The objective of this work is to understand the fluctuating nature of wind speed characteristics on different time scales and to find the long-term annual trends of wind speed at different locations in South Africa. The hourly average mean wind speed values over a period of 20 years are used to achieve the set objective. Wind speed frequency, directional availability of maximum mean wind speed, total energy, annual energy yield and plant capacity factors are determined for seven locations situated both inland and along the coast of South Africa. The highest mean wind speed (6.01 m/s) is obtained in Port Elizabeth and the lowest mean wind speed (3.86 m/s) is obtained in Bloemfontein. Wind speed increased with increasing latitudes at coastal sites (Cape Town, Durban, East London and Port Elizabeth), while the reverse trend was observed at inland locations (Bloemfontein, Johannesburg and Pretoria). Noticeable annual changes and relative wind speed values are found at coastal locations compared to inland sites. The energy pattern factor, also known as the cube factor, varied between a minimum of 1.489 in Pretoria and a maximum of 1.858 in Cape Town. Higher energy pattern factor (EPF) values correspond to sites with fair to good wind power potential. Finally, Cape Town, East London and Port Elizabeth are found to be good sites for wind power deployments based on the wind speed and power characteristics presented in this study.


Assuntos
Vento , África do Sul , Cidades , Londres
8.
Environ Sci Pollut Res Int ; 29(57): 85855-85868, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33988843

RESUMO

The optimal design and performance monitoring of wind farms depend on the precise assessment of spatial and temporal distribution of wind speed. The aim of this research is to investigate the appropriateness of nine popular probability distribution models (exponential, gamma, generalised extreme value, inverse Gaussian, Kumaraswamy, log-logistic, lognormal, Nakagami, and Weibull) for the assessment of wind speed distribution (WSD) at 10 sites situated at topographically distinct locations in Tamil Nadu, India, based on 39 years of data. The results suggest that a single distribution cannot produce best fit for all the stations. On an individual level, the generalised extreme value distribution provided the most suitable fit for majority of the stations, followed by the Kumaraswamy distribution. The Kumaraswamy distribution has performed well even if the WSD of the station is negatively skewed. Hence, based on the ranking and performance consistency, the Kumaraswamy distribution can be preferred irrespective of the topographical heterogeneity of the stations.


Assuntos
Fontes Geradoras de Energia , Vento , Índia , Distribuição Normal , Probabilidade
9.
Anaerobe ; 73: 102499, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34890812

RESUMO

BACKGROUND AND OBJECTIVES: Clostridium perfringens is a causative agent of enteric infections in animals including poultry by producing twenty different types of toxins. A single strain produces only a subset of these toxins, which form the basis of its classification into seven toxinotypes (A-G). C. perfringens toxinotype A is a widespread cause of necrotic enteritis (NE) in poultry. The current study was conducted to determine the prevalence of different toxins and antimicrobial susceptibility of C. perfringens isolated from Pakistan NE affected poultry. METHODS: A total of 134 intestinal samples of the diseased birds were collected postmortem and processed for isolation of C. perfringens using tryptose sulphite cycloserine (TSC) agar supplemented with d-cycloserine. Isolates were confirmed by Gram's staining, biochemical and molecular analyses. Toxinotyping was performed by multiplex PCR. Antimicrobial susceptibility profile of isolates was performed by Kirby Bauer disc diffusion method. RESULTS: A total of 34 strains of C. perfringens were isolated from 134 samples with prevalence rate of 25.37%. All the isolated strains were toxinotype A, as they were positive for alpha toxin (CPA) and negative for other tested toxins such as beta (CPB), epsilon (ETX), iota (ITX), enterotoxin (CPE), toxin perfringens large (TpeL) and necrotic B-like toxin (NetB). Interestingly, all the isolated strains of C. perfringens were multidrug resistant. The highest resistance was observed against Neomycin, Trimethoprim, Tetracycline and Lincomycin which are routinely used at Pakistan poultry production. CONCLUSION: C. perfringens toxinotype A is prevalent in Pakistan poultry. Incidence of C. perfringens with prevalence rate of 25.37% can pose serious threat to Pakistan's poultry industry given that all the isolated strains were multidrug resistant. Our findings highlight the need for new antibiotics and antibiotic alternatives to overcome multidrug resistance.


Assuntos
Toxinas Bacterianas , Infecções por Clostridium , Enterite , Doenças das Aves Domésticas , Animais , Antibacterianos/farmacologia , Toxinas Bacterianas/análise , Toxinas Bacterianas/genética , Galinhas , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/veterinária , Clostridium perfringens/genética , Enterite/veterinária , Enterotoxinas/genética , Paquistão , Aves Domésticas , Doenças das Aves Domésticas/epidemiologia
10.
APMIS ; 129(8): 461-469, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33950561

RESUMO

Enterobacter cloacae (E. cloacae) is an emerging nosocomial pathogen that had acquired antibiotic resistance against multiple classes of antibiotics. The current study was aimed to isolate and characterize lytic bacteriophage against E. cloacae. The bacteriophage EBP was isolated from a sewage water sample using E. cloacae as a host strain by double-layer agar technique. EBP was found stabile at a wide range of temperatures (25, 37, 60, and 80°C) and pH (5, 6, 7, 8, and 9) with antibacterial activity up to 24 h of infection. The latent period of EBP was 20 min with a burst size of 252 phages per cell. It showed a narrow host range and infected 12/21 (57%) isolates of E. cloacae tested. It has helical symmetry with a head size of 105 and 120 nm long tail with contractile sheath. The EBP has 179.1 kb long double-stranded DNA genome with 44.8% GC content. Majority of identified ORFs (187/281) were encoding putative proteins with unknown function. Necessary replication enzymes, structural proteins, and lytic enzymes were detected in the genome of EBP. Phylogenetic analysis revealed that EBP closely resembles with Coronobacter phage vB_CsaM_IeN, vB_CsaM_IeE, vB_CsaM_IeB, and Citrobacter phage Margaery. Based on electron microscopy and molecular characterization, EBP was classified as a Myoviridae phage.


Assuntos
Bacteriófagos/isolamento & purificação , Genoma Viral , Myoviridae/isolamento & purificação , Bacteriófagos/classificação , Bacteriófagos/genética , Bacteriófagos/fisiologia , Enterobacter cloacae/virologia , Tamanho do Genoma , Especificidade de Hospedeiro , Myoviridae/classificação , Myoviridae/genética , Myoviridae/fisiologia , Filogenia , Esgotos/virologia
11.
J Mol Graph Model ; 100: 107665, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32682308

RESUMO

The present study explores a series of novel donor-π-acceptor (D-π-A) molecules containing 4,4'-dimethyldiphenylamine moiety as donor, 4,4'-dinitrodiphenylborane as acceptor while different π-bridges as efficient linkers between them, which comprises of (-HCCH-)n, (-Ph-)n and (-Ph ̶ HCCH-)n combinations for compounds in series 1, 2 and 3, respectively. Quantum chemical computations are applied to calculate the linear polarizability (α), first (ß) and second (γ) hyperpolarizabilities. A comparative analysis is performed considering an increase of NLO polarizabilities as a function of different π-linkers. Among the investigated compounds, 3c shows the largest first and second hyperpolarizabilities of 1378 × 10-30 and 34971 × 10-36 esu, respectively. Interestingly, an increase in NLO polarizability is observed by modifying the π-conjugated bridges and the largest NLO polarizability is observed for series 3 possessing (Ph ̶ HCCH-)n π-linker which is found due to its lower transition energy and higher oscillator strengths. Furthermore, TD-DFT investigations, frontier molecular orbitals (FMOs) and electron density difference (EDD) maps analysis have shown a more efficient intramolecular charge transfer character from donor to acceptor moieties through (Ph ̶ HCCH-)n π-linkers. The density of states (DOS) maps are showing explicit contributions of electronic states from different fragments of a molecular system where the partial contributions of (Ph ̶ HCCH-)n π-linkers is seen significant in HOMO-LUMO orbitals of all the systems in series number 3. Thus, we believe that our study will highlight the importance of different D-π-A chromophores having variant types of π-conjugation cores as discussed in the present investigation.

12.
Pak J Pharm Sci ; 29(5): 1535-1540, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27731809

RESUMO

A lot of treatment strategies available for diabetes but its complications are still a medical problem around the globe. It demands to find out some alternative therapeutic measures. In order to investigate the anti-diabetic potential of probiotics and natural extracts, this study was designed. Accordingly, a local source of yogurt probiotic strain Lactobacillus fermentum was isolated and characterized that showed its probiotic properties. Besides this, natural extracts of plants fruits like java plum (Syzygium cumini) and bitter gourd (M. charantia) were made. Lactobacillus fermentum and the extracts were administered individually as well as in combination to diabetes induced mice. Different parameters like body weight, blood glucose level and lipid profile including total cholesterol, HDL & LDL were analyzed before and after treatment. The results showed that Lactobacillus fermentum and natural extracts have hypoglycemic as well hypolipidemic activity against diabetic mice. This study can further investigated to screen potential compounds from these extracts to control the glucose and the lipid levels in diabetic patients.


Assuntos
Glicemia/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Hipoglicemiantes/farmacologia , Hipolipemiantes/farmacologia , Limosilactobacillus fermentum/fisiologia , Lipídeos/sangue , Extratos Vegetais/farmacologia , Probióticos , Syzygium , Animais , Biomarcadores/sangue , Glicemia/metabolismo , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/microbiologia , Feminino , Frutas , Hipoglicemiantes/isolamento & purificação , Hipolipemiantes/isolamento & purificação , Camundongos , Momordica charantia/química , Fitoterapia , Extratos Vegetais/isolamento & purificação , Plantas Medicinais , Estreptozocina , Syzygium/química
13.
Ecotoxicol Environ Saf ; 73(7): 1820-7, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20810165

RESUMO

This study was conducted to investigate the concentrations of heavy metals in soil and vegetables, and human health risks through ingestion of contaminated vegetables. Soil and vegetable samples were collected from different locations in Gilgit, northern Pakistan, and analyzed for Cd, Cu, Ni, Pb and Zn. Plant transfer factors (PTF), daily intake of metals (DIM) and health risk index (HRI) were also calculated. The concentrations of Cd, Cu and Zn exceeded their respective permissible limits in soil samples. The highest concentrations of Cu, Ni, Pb and Zn were observed in the edible parts of Malva neglecta, Brassica oleracea, Mintha sylvestris and Brassica campestris, respectively. PTF values were lower for all the selected heavy metals, except for Cd. Furthermore, the HRI values were within the safe limit (<1) except for Pb; therefore, the health risks of metals through ingestion of vegetables were of great concern in the study area.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Monitoramento Ambiental/estatística & dados numéricos , Contaminação de Alimentos/estatística & dados numéricos , Metais Pesados/análise , Solo/química , Verduras/química , Análise de Variância , Exposição Ambiental/normas , Humanos , Paquistão , Saúde Pública , Medição de Risco , Especificidade da Espécie , Espectrofotometria Atômica
14.
Environ Sci Pollut Res Int ; 17(2): 288-96, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19333640

RESUMO

BACKGROUND, AIM, AND SCOPE: Soil contamination with heavy metals occurs as a result of both anthropogenic and natural activities. Heavy metals could have long-term hazardous impacts on the health of soil ecosystems and adverse influences on soil biological processes. Soil enzymatic activities are recognized as sensors towards any natural and anthropogenic disturbance occurring in the soil ecosystem. Similarly, microbial biomass carbon (MBC) is also considered as one of the important soil biological activities frequently influenced by heavy metal contamination. The polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) has recently been used to investigate changes in soil microbial community composition in response to environmental stresses. Soil microbial community structure and activities are difficult to elucidate using single monitoring approach; therefore, for a better insight and complete depiction of the soil microbial situation, different approaches need to be used. This study was conducted in a greenhouse for a period of 12 weeks to evaluate the changes in indigenous microbial community structure and activities in the soil amended with different application rates of Cd, Pb, and Cd/Pb mix. In a field environment, soil is contaminated with single or mixed heavy metals; so that, in this research, we used the selected metals in both single and mixed forms at different application rates and investigated their toxic effects on microbial community structure and activities, using soil enzyme assays, plate counting, and advanced molecular DGGE technique. Soil microbial activities, including acid phosphatase (ACP), urease (URE), and MBC, and microbial community structure were studied. MATERIALS AND METHODS: A soil sample (0-20 cm) with an unknown history of heavy metal contamination was collected and amended with Cd, Pb, and Cd/Pb mix using the CdSO(4) and Pb(NO(3))(2) solutions at different application rates. The amended soils were incubated in the greenhouse at 25 +/- 4 degrees C and 60% water-holding capacity for 12 weeks. During the incubation period, samples were collected from each pot at 0, 2, 9, and 12 weeks for enzyme assays, MBC, numeration of microbes, and DNA extraction. Fumigation-extraction method was used to measure the MBC, while plate counting techniques were used to numerate viable heterotrophic bacteria, fungi, and actinomycetes. Soil DNAs were extracted from the samples and used for DGGE analysis. RESULTS: ACP, URE, and MBC activities of microbial community were significantly lower (p < 0.05) in the metal-amended samples than those in the control. The enzyme inhibition extent was obvious between different incubation periods and varied as the incubation proceeded, and the highest rate was detected in the samples after 2 weeks. However, the lowest values of ACP and URE activities (35.6% and 36.6% of the control, respectively) were found in the Cd(3)/Pb(3)-treated sample after 2 weeks. Similarly, MBC was strongly decreased in both Cd/Pb-amended samples and highest reduction (52.4%) was detected for Cd(3)/Pb(3) treatment. The number of bacteria and actinomycetes were significantly decreased in the heavy metal-amended samples compared to the control, while fungal cells were not significantly different (from 2.3% to 23.87%). In this study, the DGGE profile indicated that the high dose of metal amendment caused a greater change in the number of bands. DGGE banding patterns confirmed that the addition of metals had a significant impact on microbial community structure. DISCUSSION: In soil ecosystem, heavy metals exhibit toxicological effects on soil microbes which may lead to the decrease of their numbers and activities. This study demonstrated that toxicological effects of heavy metals on soil microbial community structure and activities depend largely on the type and concentration of metal and incubation time. The inhibition extent varied widely among different incubation periods for these enzymes. Furthermore, the rapid inhibition in microbial activities such as ACP, URE, and MBC were observed in the 2 weeks, which should be related to the fact that the microbes were suddenly exposed to heavy metals. The increased inhibition of soil microbial activities is likely to be related to tolerance and adaptation of the microbial community, concentration of pollutants, and mechanisms of heavy metals. The DGGE profile has shown that the structure of the bacterial community changed in amended heavy metal samples. In this research, the microbial community structure was highly affected, consistent with the lower microbial activities in different levels of heavy metals. Furthermore, a great community change in this study, particularly at a high level of contamination, was probably a result of metal toxicity and also unavailability of nutrients because no nutrients were supplied during the whole incubation period. CONCLUSIONS: The added concentrations of heavy metals have changed the soil microbial community structure and activities. The highest inhibitory effects on soil microbial activities were observed at 2 weeks of incubation. The bacteria were more sensitive than actinomycetes and fungi. The DGGE profile indicated that bacterial community structure was changed in the Cd/Pb-amended samples, particularly at high concentrations. RECOMMENDATIONS AND PERSPECTIVES: The investigation of soil microbial community structure and activities together could give more reliable and accurate information about the toxic effects of heavy metals on soil health.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Microbiologia do Solo , Poluentes do Solo/toxicidade , Solo/análise , Fosfatase Ácida/análise , Fosfatase Ácida/metabolismo , Bactérias/classificação , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Biomassa , Cádmio/metabolismo , Contagem de Colônia Microbiana , Ecossistema , Fungos/classificação , Fungos/efeitos dos fármacos , Fungos/metabolismo , Chumbo/metabolismo , RNA Ribossômico 16S/metabolismo , Poluentes do Solo/metabolismo , Urease/análise , Urease/metabolismo
15.
J Environ Manage ; 90(11): 3451-7, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19535201

RESUMO

This study was conducted to investigate the effectiveness of a continuous free surface flow wetland for removal of heavy metals from industrial wastewater, in Gadoon Amazai Industrial Estate (GAIE), Swabi, Pakistan. Industrial wastewater samples were collected from the in-let, out-let and all cells of the constructed wetland (CW) and analyzed for heavy metals such as lead (Pb), cadmium (Cd), iron (Fe), nickel (Ni), chromium (Cr) and copper (Cu) using standard methods. Similarly, samples of aquatic macrophytes and sediments were also analyzed for selected heavy metals. Results indicate that the removal efficiencies of the CW for Pb, Cd, Fe, Ni, Cr, and Cu were 50%, 91.9%, 74.1%, 40.9%, 89%, and 48.3%, respectively. Furthermore, the performance of the CW was efficient enough to remove the heavy metals, particularly Cd, Fe, and Cu, from the industrial wastewater fed to it. However, it is suggested that the metal removal efficiency of the CW can be further enhanced by using proper management of vegetation and area expansion of the present CW.


Assuntos
Resíduos Industriais , Metais Pesados/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Áreas Alagadas
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