Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 40.101
Filtrar
1.
Rev Environ Contam Toxicol ; 249: 71-131, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30806802

RESUMO

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders, and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physicochemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metal-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches; evaluates their efficacy to remove toxic metals from our natural environment; explores current scientific progresses, field experiences, and sustainability issues; and revises world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in the twenty-first century.


Assuntos
Biodegradação Ambiental , Metais Pesados , Poluentes do Solo , Plantas , Solo
2.
Rev Environ Contam Toxicol ; 251: 25-108, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31011832

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) are a class of hazardous organic contaminants that are widely distributed in nature, and many of them are potentially toxic to humans and other living organisms. Biodegradation is the major route of detoxification and removal of PAHs from the environment. Aerobic biodegradation of PAHs has been the subject of extensive research; however, reports on anaerobic biodegradation of PAHs are so far limited. Microbial degradation of PAHs under anaerobic conditions is difficult because of the slow growth rate of anaerobes and low energy yield in the metabolic processes. Despite the limitations, some anaerobic bacteria degrade PAHs under nitrate-reducing, sulfate-reducing, iron-reducing, and methanogenic conditions. Anaerobic biodegradation, though relatively slow, is a significant process of natural attenuation of PAHs from the impacted anoxic environments such as sediments, subsurface soils, and aquifers. This review is intended to provide comprehensive details on microbial degradation of PAHs under various reducing conditions, to describe the degradation mechanisms, and to identify the areas that should receive due attention in further investigations.


Assuntos
Bactérias Anaeróbias/metabolismo , Biodegradação Ambiental , Poluentes Ambientais/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Nitratos
3.
J Environ Manage ; 252: 109675, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31614261

RESUMO

Microbial degradation is the main responsible for polycyclic aromatic hydrocarbons (PAHs) removal from contaminated soils, and the understanding of this process is pivotal to define effective bioremediation approaches. To evaluate the contribution of several microbial groups in soil anthracene and benzo[a]pyrene degradation, the analysis of phospholipid fatty acid (PLFA) profiles and machine learning techniques were employed. To this end, PLFAs and PAH concentrations were analysed, along 274 days of incubation in mesocosms, in soils artificially contaminated with anthracene and benzo[a]pyrene, subjected to different treatments: untreated soil and soils treated with biowaste compost or fungal consortium. Random forest models, figuring anthracene or benzo[a]pyrene concentrations as dependent variables and PLFAs as predictors, were then built to evaluate the contribution of each variable in PAH degradation. PLFA profiles varied substantially among soil treatments and along time, with the increase of Actinomycetes in soils added with fungi and other Gram+ bacteria in compost amended soils. The former, together with fungi, are primarily responsible for anthracene and benzo[a]pyrene degradation in both treated soils, a process in which also metanotrophs and other Gram+ and Gram- bacteria participate. In untreated soil, the cooperation of a multitude of different microorganisms was, instead, responsible for PAH removal, a process with lower efficiency in respect to treated soils.


Assuntos
Compostagem , Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Biodegradação Ambiental , Fungos , Solo , Microbiologia do Solo
4.
Bioresour Technol ; 294: 122185, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31569046

RESUMO

Due to the toxicological nature of N-methylpyrrolidone (NMP), the conventional anaerobic bioprocess is quite ineffective for NMP removal from wastewater. In order to achieve effective NMP biodegradation under anoxic condition, Paracoccus pantotrophus NJUST38 was isolated for the first time. The supplementation of nitrate into anoxic system resulted in complete removal of 5 mM NMP by NJUST38 within 11 h compared to 24% in the anaerobic control system in the absence of nitrate. Genome characterization revealed that NMP biodegradation catalyzed by several key enzymes/genes, including N-methylhydantoin amidohydrolase (hyuB), methyltransferase (cobA), 4-aminobutyrate-2-oxoglutarate transaminase (gabT), succinate-semialdehyde dehydrogenase (gabD) and so on. NMP biodegradation pathway was proposed based on several intermediates, where NMP was biodegraded mainly for providing electrons and reducing power to support microbial denitrification through tricarboxylic acid (TCA) cycle. The proposed mechanism should aid our mechanistic understanding of NMP biodegradation by Paracoccus pantotrophus and the development of sustainable bioremediation strategies.


Assuntos
Paracoccus pantotrophus , Paracoccus , Biodegradação Ambiental , Genômica , Nitratos , Pirrolidinonas
5.
Cell Host Microbe ; 26(4): 446-448, 2019 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-31600496

RESUMO

The diet-microbiome interaction can positively or negatively affect our health depending on dietary habits. In this issue of Cell Host & Microbe, Wolf et al. (2019) highlight the beneficial roles of gut commensal Collinsella in degrading potentially toxic food contaminants, called Maillard reaction products, found in processed foods.


Assuntos
Microbioma Gastrointestinal , Bactérias , Biodegradação Ambiental , Dieta , Manipulação de Alimentos , Humanos
6.
An Acad Bras Cienc ; 91(3): e20180694, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31618412

RESUMO

The strains CM-Z19 and CM-Z6, which are capable of highly degrading chlorpyrifos-methyl, were isolated from soil. They were identified as Bacillus megaterium CM-Z19 and Pseudomonas syringae CM-Z6, respectively, based on the 16S rRNA and an analysis of their morphological, physiological and biochemical characteristics. The strain CM-Z19 showed 92.6% degradation of chlorpyrifos-methyl (100 mg/L) within 5 days of incubation, and the strain CM-Z6 was 99.1% under the same conditions. In addition, the degradation characteristics of the two strains were compared and studied, and the results showed that the strain CM-Z19 had higher phosphoesterase activity and ability to degrade the organophosphorus pesticide than did the strain CM-Z6. However, the strain CM-Z19 could not degrade its first hydrolysis metabolite 3,5,6-trichloro-2-pyridinol (TCP) and could not completely degrade chlorpyrifos-methyl. The strain CM-Z6 could effectively degrade TCP and could degrade chlorpyrifos-methyl more quickly than strain CM-Z19.


Assuntos
Bacillus megaterium/metabolismo , Biodegradação Ambiental , Clorpirifos/análogos & derivados , Praguicidas/metabolismo , Pseudomonas syringae/metabolismo , Bacillus megaterium/isolamento & purificação , Clorpirifos/isolamento & purificação , Clorpirifos/metabolismo , Inseticidas/isolamento & purificação , Inseticidas/metabolismo , Praguicidas/isolamento & purificação , Pseudomonas syringae/isolamento & purificação , RNA Ribossômico 16S/metabolismo , Microbiologia do Solo
7.
Bioresour Technol ; 294: 122190, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31585342

RESUMO

This study report kinetics of PAHs and crude oil degradation by a newly isolated multiple heavy metal tolerant Novosphingobium panipatense P5:ABC. The isolate showed hydrocarbon degrading enzyme activities namely alkane hydroxylase, catechol 1,2-dioxygenase and catechol 2,3-dioxygenase. The level of C23O activity was 9.63 times higher than C12O thus suggesting active involvement of meta-cleavage pathway. The data of biodegradation of hydrocarbons fitted well to the first order kinetic model. The degradation rate was highest for phenanthrene followed by crude oil, and fluoranthene. We have further reported the estimate of fundamental kinetic parameters, half-saturation constant (Ks) and maximum degradation rates (Vmax) for biodegradation of phenanthrene and fluoranthene. Overall characterization underscores the potential of Novosphingobium in bioremediation of crude oil polluted sites.


Assuntos
Metais Pesados , Petróleo , Biodegradação Ambiental , Hidrocarbonetos , Cinética
9.
Water Environ Res ; 91(10): 1326-1341, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31523907

RESUMO

This survey of 2018 literature on substratum-associated microbiota presents brief highlights on research findings from primarily freshwaters, but includes those from a variety of aquatic ecosystems. Coverage of topics associated with benthic algae and cyanobacteria, though not comprehensive, includes new methods, taxa new to science, nutrient dynamics, trophic interactions, herbicides and other pollutants, metal contaminants, nuisance, bloom-forming and harmful algae, bioassessment, and bioremediation. Coverage of bacteria, also not comprehensive, focused on methylation of mercury, metal contamination, toxins, and other environmental pollutants, including oil, as well as the use of benthic bacteria as bioindicators, in bioassessment tools and in biomonitoring. Additionally, we cover trends in recent and emerging topics on substratum-associated microbiota of relevance to the Water Environment Federation. PRACTITIONER POINTS: This review of literature from 2018 on substratum-associated microbiota presents highlights of findings on algae, cyanobacteria, and bacteria from primarily freshwaters. Topics covered that focus on algae and cyanobacteria include findings on new methods, taxa new to science, nutrient dynamics, trophic interactions, herbicides and other pollutants, metal contaminants, nuisance, bloomforming and harmful algae, bioassessment, and bioremediation. Topics covered that focus on bacteria include findings on methylation of mercury, metal contamination, toxins and other environmental pollutants, including oil, as well as the us e of benthic bacteria as bioindicators, in bioassessment tools and in biomonitoring. A brief presentation of new, noteworthy and emerging topics on substratum-associated microbiota, build on those from 2017, to highlight those of particular relevance to the Water Environment Federation.


Assuntos
Cianobactérias , Microbiota , Biodegradação Ambiental , Monitoramento Ambiental , Água Doce
10.
Chemosphere ; 235: 1154-1161, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561306

RESUMO

A MBBR-MBR system has been developed with marine microorganisms enriched for saline wastewater treatment in this work, showing high COD and NH3-N removals. The behaviour of fouling-related components (EPS and SMP) has been studied as functions of operating time (40-90 days), salinity (0-30 g/L NaCl) and backflow ratio (0-300%, from MBR to MBBR). High biodegradability of the MBBR-MBR at optimal conditions can induce more biodegradation of humic acid-like (λex/λem: 350nm/430 nm) and fulvic acid-like (260nm/445 nm) molecules to soluble microbial by-product-like molecules (275nm/325 nm), reducing the membrane biofouling rate. The biodegradation process is suggested by the excitation-emission matrix (EEM) images. In the study of sudden salinity shock, results show that real-time monitoring the concentration of biofoulants is more effective (operative time extended by 60%) than monitoring the transmembrane pressure (operative time extended by 33%) to prevent membrane fouling. Due to an early warning from the real-time monitoring, the coming membrane-fouling is predictable and the operating conditions, such as backflow ratio, can be changed to minimize the biofouling rate.


Assuntos
Biofilmes , Incrustação Biológica/prevenção & controle , Reatores Biológicos , Membranas Artificiais , Águas Residuárias/química , Biodegradação Ambiental , Salinidade , Análise Espectral , Purificação da Água/métodos
11.
J Agric Food Chem ; 67(41): 11373-11379, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31539240

RESUMO

Cadmium bioremediation with metal-binding proteins is primarily conducted using metallothioneins (MTs). However, in the present study, we investigated a non-MT cadmium-binding protein from Lentinula edodes (LECBP) as a remediation tool for cadmium biosorption in Escherichia coli. The results indicated that the expression of LECBP significantly enhanced the cadmium biosorption capacity of transgenic E. coli. The secondary structure and conformation of LECBP were changed after binding with cadmium as evidenced by circular dichroism and fluorescence spectroscopy. The results of Fourier transform infrared spectroscopy indicated that carboxyl oxygen and amino nitrogen atoms were involved in the interaction between LECBP and cadmium. The results further demonstrated that glutamic acid and histidine residues are the potential binding sites. Our results have thus provided new insights into cadmium bioremediation in an aquatic environment.


Assuntos
Cádmio/metabolismo , Metalotioneína/metabolismo , Proteínas de Plantas/metabolismo , Cogumelos Shiitake/genética , Sítios de Ligação , Biodegradação Ambiental , Cádmio/química , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Metalotioneína/química , Metalotioneína/genética , Proteínas de Plantas/química , Proteínas de Plantas/genética , Cogumelos Shiitake/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier
12.
J Environ Manage ; 249: 109408, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31513965

RESUMO

The aim of this study was to assess the effects of soil amendments (organic and inorganic) on phytoavailability and leaching of cadmium (Cd) and lead (Pb) during enhanced phytoextraction. The vertical column study was carried out to investigate the metal leaching meanwhile studying plant biomass and metals uptake for phytoextraction by Pelargonium hortroum. For this purpose, soil amendments at several concentration levels, such as ethylene diaminetetraacetic acid (EDTA 0, 4, 5 mmol kg-1), ammonium nitrate (0, 8, 10 mmol kg-1), citric acid (0, 8, 10 mmol kg-1), compost (0, 8%, 10%) and titanium dioxide nanoparticles (TNPs, 0, 80, 100 mg kg-1) were used. Results revealed that EDTA efficiently improved Cd and Pb accumulation (mg kg-1) in shoots and roots. Cd accumulation was significantly increased by 270%, 44%, 145%, and 6.4% in shoot and 94%, 19%, 48% and 14% in root upon EDTA, ammonium nitrate, citric acid and TNPs application, respectively compared to the control without amendment (WA). Similarly, Pb accumulation was significantly increased by 71%, 58% and 52% in shoot and 88.8%, 70.6% and 64.6% in root upon exposure to higher levels of EDTA, citric acid and ammonium nitrate, respectively when compared to the WA control. Application of TNPs reduced the Pb-accumulation in shoots and roots by 33% and 28%, respectively. Similarly, the Pb-accumulation in shoots and roots was decreased by 39% and 35%, respectively upon compost addition. Plant biomass was significantly increased upon application of soil amendments, with the exception of EDTA. The maximum Cd and Pb uptake was found in citric acid amended soil. Leachate analysis revealed that the concentrations of Cd and Pb were increased by 109% and 101% in leachates upon EDTA application as compared to other amendments. In comparison with other amendments, citric acid may be recommended as an environmentally friendly alternative for non-biodegradable EDTA for enhanced phytoextraction of Cd and Pb.


Assuntos
Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Cádmio , Ácido Edético , Chumbo , Solo
13.
Sci Total Environ ; 690: 1100-1109, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470473

RESUMO

Jarosite is an iron-hydroxysulfate mineral commonly found in acid mine drainage (AMD). Given its strong adsorption capacity and its ability to co-precipitation with heavy metals, jarosite is considered a potent scavenger of contaminants in AMD-impacted environments. Sulfate-reducing bacteria (SRB) play an important role in the reductive dissolution of jarosite; however, the mechanism involved has yet to be elucidated. In this study, an indigenous SRB community enriched from the Dabaoshan mine area (Guangdong, China) was employed to explore the mechanism of the microbial reduction of jarosite. Different cultures, with or without dissolved sulfate and the physical separation of jarosite from bacteria by dialysis bags, were examined. Results indicate that the reduction of jarosite by SRB occurred via an indirect mechanism. In systems with dissolved sulfate, lactate was incompletely oxidized to acetate coupled with the reduction of SO42- to S2-, which subsequently reduced the Fe3+ in jarosite, forming secondary minerals including vivianite, mackinawite and pyrite. In systems without dissolved sulfate, jarosite dissolution occurred prior to reduction, and similar secondary minerals formed as well. Extracellular polymeric substances secreted by SRB appeared to facilitate the release of sulfate from jarosite. Structural sulfate in the solid phase of jarosite may not be available for SRB respiration. Although direct contact between SRB and jarosite is not necessary for mineral reduction, wrapping jarosite into dialysis bags suppressed the reduction to a certain extent. Microbial community composition differed in direct contact treatments and physical separation treatments. Physical separation of the SRB community from jarosite mineral supported the growth of Citrobacter, while Desulfosporosinus dominated in direct contact treatments.


Assuntos
Biodegradação Ambiental , Microbiologia Ambiental , Compostos Férricos , Metais Pesados , Mineração , Sulfatos , Poluentes Químicos da Água
14.
J Environ Manage ; 250: 109476, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31476519

RESUMO

Exploiting synergism between plants and microbes offers a potential means of remediating soils contaminated with petroleum hydrocarbons (PHCs). Salinity alters the physicochemical characteristics of soils and suppresses the growth of both plants and soil microbes, so the bioremediation of saline soils requires the use of plants and in microbes which can tolerate salinity. This review focuses on the management of PHC-contaminated saline soils, surveying what is currently known with respect to the potential of halophytes (plants adapted to saline environments) acting in concert with synergistic microbes to degrade PHCs. The priority is to identify optimal combinations of halophyte(s) and the bacteria present as endophytes and/or associated with the rhizosphere, and to determine what are the factors which most strongly affect their viability.


Assuntos
Petróleo , Poluentes do Solo , Biodegradação Ambiental , Hidrocarbonetos , Solo , Microbiologia do Solo
15.
J Environ Manage ; 250: 109475, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31491716

RESUMO

In this study, commercial products formulated from polyethylene (PE) with pro-oxidant additives, were subjected to abiotic and biotic environments. The materials were presumed to be oxo-biodegradable plastics with thicknesses varying between 30 and 70 µm, and calcium carbonate (CaCO3) filler content reaching up to 11 wt%. Accelerated (aging) weathering tests conducted revealed that UV radiation triggered the biodegradation mechanism. Weight loss reached 50% after exposure to weathering which was attributed to triggering the fragmentation of the plastic films. Furthermore, some 83% of weight loss was estimated after 12 months of soil burial. Fluctuation of weight in mid exposure time spans was related to the cross-linking reaction within the polymeric matrix. The mechanical properties investigated along with the thermal stability profile determined for the materials showed that weathering was more severe than soil burial. Thermogravimetry revealed that onset temperature (Tos) was lower than conventional PO products by 25 °C. This could be attributed to the thermal response of the materials due to presence of ion salts and sterates within their composition. The claims by the manufacturing companies which provided the original specimens under an environmentally friendly pretence is disputed due to the fact that none of the products actually showed evidence of major fragmentation or deterioration after exposure to harsh environments. The work also paves the way in standardising assessment methodology for examining biodegradable plastics.


Assuntos
Plásticos , Polietileno , Biodegradação Ambiental , Espécies Reativas de Oxigênio , Solo
16.
J Environ Manage ; 250: 109455, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31491718

RESUMO

Because of the high production of oil and gas in Qatar, the likelihood of oil spill occurrence is most probably susceptible to happen. Contaminated soil treatment is very expensive. Cost effective mechanisms are investigated to treat this threatening issue. For that reason, bioremediation and biotechnology tools are introduced to help accelerate and remove the pollution caused by the contamination process. This paper demonstrated the importance of optimising the treatment conditions to the indigenous bacterial strain to obtain the highest biodegradation efficiency rates. The usage of biopile system technology was used with biostimulation and bioaugmentation processes. The indigenous Bacillus sonorensis (B. sonorensis) D1 bacterium played a crucial role in the biodegradation process when introduced to optimized conditions; carbon/nitrogen/phosphorus (C/N/P) (100/10/1), temperature (37 °C), surfactant tween 80 (0.12% (v/w)), and moisture (10%). Gas chromatography (mass spectrometry/flame ionization detector) (GC- (MS/FID)), Fourier transform infrared (FTIR), and colony-forming unit (CFU) analyses were performed. The diesel range organics (DRO) and polycyclic aromatic hydrocarbons (PAH) removal (%) of the weathered oil contaminated soil reached, after 160 days, 39.2% and 32.4% simultaneously when ammonium nitrate was used as a nitrogen source. Whereas urea inhibited the oil degradation process and caused the pH to rise to 9.55.


Assuntos
Bacillus , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Biodegradação Ambiental , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos , Microbiologia do Solo
17.
J Environ Manage ; 250: 109409, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31521033

RESUMO

The purpose of this study was to analyze the rate of sporulation, richness, and spore diversity of dematiaceous and Ingoldian fungi colonizing Typha latifolia leaves during a 40-day period of decomposition, as well as the loss of mass in Typha latifolia, in four riverine wetlands of Pampean plain (Argentina) with different water quality. Higher sporulation rates, richness, and diversity of the fungi as well as loss of mass of the leaves that they colonized were associated with lower water quality. Anguilospora longissima, Arthrinium sp., Margaritispora aquatica, and Tricellula botryosa were dominant taxa. Redundancy analysis showed two fungal assemblages related to different environmental conditions. One assemblage was related to higher nutrient levels and higher temperature, characterized mainly by dematiaceous fungi. The other assemblage was related to higher levels of pH and dissolved oxygen, which was mainly represented by Ingoldian fungi. The results obtained in our study demonstrated the link between these fungal assemblages and changes in water quality, revealing their potential as indicators of environmental changes in rivers exposed to different types of land use.


Assuntos
Typhaceae , Argentina , Biodegradação Ambiental , Fungos , Folhas de Planta , Qualidade da Água , Áreas Alagadas
18.
J Environ Manage ; 250: 109385, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31521920

RESUMO

In this study, bamboo carrier based lab scale compost biofilter was evaluated to treat synthetic waste air containing trichloroethylene (TCE) under continuous operation mode. The effect of inlet TCE concentration and gas flow rate and its removal was investigated. Maximum TCE removal efficiency was found to be 89% under optimum conditions of inlet 0.986 g/m3 TCE concentration corresponding to a loading rate of 43 g/m3 h and 0.042 m3/h gas flow rate at empty bed residence time (EBRT) of 2 min. For the first time, Artificial Neural Network (ANN) was applied to predict the performance of the compost biofilter in terms of TCE removal. The ANN model used a three layer feed forward based Levenberg-Marquardt algorithm, and its topology consisted of 3-25-1 as the optimum number for the three layers (input, hidden and output). An excellent match between the experimental and ANN predicted the value of TCE removal was obtained with a coefficient of determination (R2) value greater than 0.99 during the model training, validation, testing and overall. Furthermore, statistical analysis of the ANN model performance mediated its prediction accuracy of the bioreactor to treat TCE contaminated systems.


Assuntos
Tricloroetileno , Biodegradação Ambiental , Reatores Biológicos , Filtração , Gases , Redes Neurais (Computação)
19.
J Environ Manage ; 250: 109530, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31521922

RESUMO

This work aimed at elucidating the role of bacteria present in the gut of the earthworm Metaphire posthuma in plant growth promotion and toxic trace elements (TTEs) bioremediation. We isolated and identified three bacterial strains Bacillus safensis (MF 589718), Bacillus flexus (MF 589717) and Staphylococcus haemolyticus (MF 589719) among which the Bacillus strains appeared to be significantly more potent than the Staphylococcus strain (P < 0.05) in promoting plant growth and removing TTE (Cr(VI), Cu(II) and Zn(II)) from aqueous media. These strains exhibited several plant growth promoting traits (e.g., indole acetic acid (IAA), gibberellic acid (GA) and ammonium ion production, 1-aminocyclopropane- 1-carboxylic acid (ACC) deaminase activity, and phosphate solubilizing potential). In a pot trial, the gut isolates improved Vigna radiata seed germination, and enhanced the leaf area (30-79%), total chlorophyll content (26-67%) and overall root-shoot biomass (32-83%) as compared to the control. Bacillus safensis and Bacillus flexus were equipotent in removing Cr(VI) (40.5 and 40.3%) from aqueous media; the former triumphed for Zn(II) removal (52.8%), while the latter performed better for Cu(II) removal (43.5%). The gut isolates successfully solubilized phosphate even in TTE-contaminated conditions. The results demonstrate that the earthworm's enteric bacteria possess inherent plant growth promoting, TTE resistance and phosphate solubilization (even under TTE stress) properties which can be further explored for their application in sustainable crop production and environmental management.


Assuntos
Microbioma Gastrointestinal , Oligoquetos , Oligoelementos , Animais , Biodegradação Ambiental , Ácidos Indolacéticos , Desenvolvimento Vegetal , Raízes de Plantas , Microbiologia do Solo
20.
J Environ Manage ; 250: 109549, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31545178

RESUMO

Treatment of raw textile effluent (RTE) is very difficult, due to its inherent heterogeneous, low-biodegradable and toxic compositions. Pure and mixed microbial cultures have limited metabolic capabilities in effective mineralization of complex RTE. Therefore, in this study a novel bacterial community DR4 was enriched directly into a complex RTE consisting of 27 different dyes using textile dye polluted soil as an inoculum. The rigorous enrichment process resulted in acclimatization of a taxonomically distinct bacterial population, with an abundance of the genus Comamonas in the bacterial community DR4 as compared to the abundance of Pseudomonas in the RTE respectively, as revealed by high-throughput 16S rRNA gene (V3-V4 region) sequencing. Microaerophilic treatment of RTE by enriched bacterial community DR4, in the presence of optimized electron donor (sucrose) and nitrogen source (yeast extract) resulted in 88% of American Dye Manufacturer's Institute (ADMI) removal and 98% of Chemical oxygen demand (COD) reduction within 32 h at 37 °C. In silico prediction of the functional genes within bacterial community DR4 was made by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. The PICRUSt analysis revealed high abundance of xenobiotic degradation and metabolism genes. The predicted functional genes and textile dye degradation pathways were further validated using Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FTIR) spectroscopy and High Resolution Liquid Chromatography coupled with Mass Spectrometry (HR-LCMS) based characterization of textile dye degradation metabolites. The activity of azoreductases in the cell-free extracts (CFE) of the enriched bacterial community DR4 was induced by 1.83-7.81 folds in the presence of representative textile dyes as compared to uninduced samples, which confirmed their role in textile effluent decolourization. The degradation of four representative azo dyes present in RTE such as Disperse orange 30, Reactive red 152, Direct blue 2 and Acid brown 15 depicted symmetric degradation of azo bonds by bacterial community DR4.


Assuntos
Indústria Têxtil , Têxteis , Compostos Azo , Biodegradação Ambiental , Corantes , Filogenia , RNA Ribossômico 16S , Espectroscopia de Infravermelho com Transformada de Fourier
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA