Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Environ Pollut ; : 113676, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31818614

RESUMO

CH4 oxidation in landfill cover soils plays a significant role in mitigating CH4 release to the atmosphere. Oxygen availability and the presence of co-contaminants are potentially important factors affecting CH4 oxidation rate and the fate of CH4-derived carbon. In this study, microbial populations that oxidize CH4 and the subsequent conversion of CH4-derived carbon into CO2, soil organic C and biomass C were investigated in landfill cover soils at two O2 tensions, i.e., O2 concentrations of 21% ("sufficient") and 2.5% ("limited") with and without toluene. CH4-derived carbon was primarily converted into CO2 and soil organic C in the landfill cover soils, accounting for more than 80% of CH4 oxidized. Under the O2-sufficient condition, 52.9%-59.6% of CH4-derived carbon was converted into CO2 (CECO2-C), and 29.1%-39.3% was converted into soil organic C (CEorganic-C). A higher CEorganic-C and lower CECO2-C occurred in the O2-limited environment, relative to the O2-sufficient condition. With the addition of toluene, the carbon conversion efficiency of CH4 into biomass C and organic C increased slightly, especially in the O2-limited environment. A more complex microbial network was involved in CH4 assimilation in the O2-limited environment than under the O2-sufficient condition. DNA-based stable isotope probing of the community with 13CH4 revealed that Methylocaldum and Methylosarcina had a higher relative growth rate than other type I methanotrophs in the landfill cover soils, especially at the low O2 concentration, while Methylosinus was more abundant in the treatment with both the high O2 concentration and toluene. These results indicated that O2-limited environments could prompt more CH4-derived carbon to be deposited into soils in the form of biomass C and organic C, thereby enhancing the contribution of CH4-derived carbon to soil community biomass and functionality of landfill cover soils (i.e. reduction of CO2 emission).

2.
Sci Total Environ ; 607-608: 23-31, 2017 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-28686892

RESUMO

Anaerobic oxidation of methane (AOM) is a biological process that plays an important role in reducing the CH4 emissions from a wide range of ecosystems. Arctic and sub-Arctic lakes are recognized as significant contributors to global methane (CH4) emission, since CH4 production is increasing as permafrost thaws and provides fuels for methanogenesis. Methanotrophy, including AOM, is critical to reducing CH4 emissions. The identity, activity, and metabolic processes of anaerobic methane oxidizers are poorly understood, yet this information is critical to understanding CH4 cycling and ultimately to predicting future CH4 emissions. This study sought to identify the microorganisms involved in AOM in sub-Arctic lake sediments using DNA- and phospholipid-fatty acid (PLFA)- based stable isotope probing. Results indicated that aerobic methanotrophs belonging to the genus Methylobacter assimilate carbon from CH4, either directly or indirectly. Other organisms that were found, in minor proportions, to assimilate CH4-derived carbon were methylotrophs and iron reducers, which might indicate the flow of CH4-derived carbon from anaerobic methanotrophs into the broader microbial community. While various other taxa have been reported in the literature to anaerobically oxidize methane in various environments (e.g. ANME-type archaea and Methylomirabilis Oxyfera), this report directly suggest that Methylobacter can perform this function, expanding our understanding of CH4 oxidation in anaerobic lake sediments.


Assuntos
Archaea/metabolismo , Sedimentos Geológicos/microbiologia , Lagos/microbiologia , Metano/metabolismo , Anaerobiose , Regiões Árticas , Oxirredução
3.
Arch Microbiol ; 199(6): 839-851, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28289787

RESUMO

Used lubricating oil (ULO) is a widespread contaminant, particularly throughout tropical regions, and may be a candidate for bioremediation. However, little is known about the biodegradation potential or basic microbial ecology of ULO-contaminated soils. This study aims to determine the effects of used ULO on bacterial community structure and diversity. Using a combination of culture-based (agar plate counts) and molecular techniques (16S rRNA gene sequencing and DGGE), we investigated changes in soil bacterial communities from three different ULO-contaminated soils collected from motorcycle mechanical workshops (soil A, B, and C). We further explored the relationship between bacterial community structure, physiochemical soil parameters, and ULO composition in three ULO-contaminated soils. Results indicated that the three investigated soils had different community structures, which may be a result of the different ULO characteristics and physiochemical soil parameters of each site. Soil C had the highest ULO concentration and also the greatest diversity and richness of bacteria, which may be a result of higher nutrient retention, organic matter and cation exchange capacity, as well as freshness of oil compared to the other soils. In soils A and B, Proteobacteria (esp. Gammaproteobacteria) dominated the bacterial community, and in soil C, Actinobacteria and Firmicutes dominated. The genus Enterobacter, a member of the class Gammaproteobacteria, is known to include ULO-degraders, and this genus was the only one found in all three soils, suggesting that it could play a key role in the in situ degradation of ULO-contaminated tropical Thai soils. This study provides insights into our understanding of soil microbial richness, diversity, composition, and structure in tropical ULO-contaminated soils, and may be useful for the development of strategies to improve bioremediation.


Assuntos
Bactérias/metabolismo , Biodiversidade , Lubrificantes/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biodegradação Ambiental , Lubrificantes/análise , RNA Ribossômico 16S/genética , Solo/química , Poluentes do Solo/análise , Clima Tropical
4.
Front Microbiol ; 7: 837, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27313574

RESUMO

Despite decades of research there is limited understanding of how vegetation impacts the ability of microbial communities to process organic contaminants in soil. Using a combination of traditional and molecular assays, we examined how phytoremediation with willow and/or fertilization affected the microbial community present and active in the transformation of diesel contaminants. In a pot study, willow had a significant role in structuring the total bacterial community and resulted in significant decreases in diesel range organics (DRO). However, stable isotope probing (SIP) indicated that fertilizer drove the differences seen in community structure and function. Finally, analysis of the total variance in both pot and SIP experiments indicated an interactive effect between willow and fertilizer on the bacterial communities. This study clearly demonstrates that a willow native to Alaska accelerates DRO degradation, and together with fertilizer, increases aromatic degradation by shifting microbial community structure and the identity of active naphthalene degraders.

5.
Sci Rep ; 6: 22145, 2016 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-26915282

RESUMO

Aerobic mineralization of PCBs, which are toxic and persistent organic pollutants, involves the upper (biphenyl, BP) and lower (benzoate, BZ) degradation pathways. The activity of different members of the soil microbial community in performing one or both pathways, and their synergistic interactions during PCB biodegradation, are not well understood. This study investigates BP and BZ biodegradation and subsequent carbon flow through the microbial community in PCB-contaminated soil. DNA stable isotope probing (SIP) was used to identify the bacterial guilds involved in utilizing (13)C-biphenyl (unchlorinated analogue of PCBs) and/or (13)C-benzoate (product/intermediate of BP degradation and analogue of chlorobenzoates). By performing SIP with two substrates in parallel, we reveal microbes performing the upper (BP) and/or lower (BZ) degradation pathways, and heterotrophic bacteria involved indirectly in processing carbon derived from these substrates (i.e. through crossfeeding). Substrate mineralization rates and shifts in relative abundance of labeled taxa suggest that BP and BZ biotransformations were performed by microorganisms with different growth strategies: BZ-associated bacteria were fast growing, potentially copiotrophic organisms, while microbes that transform BP were oligotrophic, slower growing, organisms. Our findings provide novel insight into the functional interactions of soil bacteria active in processing biphenyl and related aromatic compounds in soil, revealing how carbon flows through a bacterial community.


Assuntos
Bactérias/metabolismo , Benzoatos/metabolismo , Poluição Ambiental , Hidrocarbonetos Aromáticos/metabolismo , Bifenilos Policlorados/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Bactérias/genética , Biodegradação Ambiental , Compostos de Bifenilo/metabolismo , Resíduos Perigosos , RNA Ribossômico 16S/genética , Solo/química
6.
Cold Reg Sci Technol ; 96: 129-137, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24501438

RESUMO

Phytoremediation is a potentially inexpensive method of detoxifying contaminated soils using plants and associated soil microorganisms. The remote locations and cold climate of Alaska provide unique challenges associated with phytoremediation such as finding effective plant species that can achieve successful site clean-up despite the extreme environmental conditions and with minimal site management. A long-term assessment of phytoremediation was performed which capitalized on a study established in Fairbanks in 1995. The original study sought to determine how the introduction of plants (Festuca rubra, Lolium multiflorum), nutrients (fertilizer), or their combination would affect degradation of petroleum hydrocarbon (TPH) contaminated soils (crude oil or diesel) over time. Within the year following initial treatments, the plots subjected to both planting and/or fertilization showed greater overall decreases in TPH concentrations in both the diesel and crude oil contaminated soils relative to untreated plots. We re-examined this field site after 15 years with no active site management to assess the long-term effects of phytoremediation on colonization by native and non-native plants, their rhizosphere microbial communities and on petroleum removal from soil. Native and non-native vegetation had extensively colonized the site, with more abundant vegetation found on the diesel contaminated soils than the more nutrient-poor, more coarse, and acidic crude oil contaminated soils. TPH concentrations achieved regulatory clean up levels in all treatment groups, with lower TPH concentrations correlating with higher amounts of woody vegetation (trees & shrubs). In addition, original treatment type has affected vegetation recruitment to each plot with woody vegetation and more native plants in unfertilized plots. Bacterial community structure also varies according to the originally applied treatments. This study suggests that initial treatment with native tree species in combination with grasses could be an effective means for phytoremediating petroleum contaminated soils and promoting ecological recovery in cold regions.

7.
Biotechnol Adv ; 31(2): 154-65, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23022353

RESUMO

Microbial biodegradation and biotransformation reactions are essential to most bioremediation processes, yet the specific organisms, genes, and mechanisms involved are often not well understood. Stable isotope probing (SIP) enables researchers to directly link microbial metabolic capability to phylogenetic and metagenomic information within a community context by tracking isotopically labeled substances into phylogenetically and functionally informative biomarkers. SIP is thus applicable as a tool for the identification of active members of the microbial community and associated genes integral to the community functional potential, such as biodegradative processes. The rapid evolution of SIP over the last decade and integration with metagenomics provide researchers with a much deeper insight into potential biodegradative genes, processes, and applications, thereby enabling an improved mechanistic understanding that can facilitate advances in the field of bioremediation.


Assuntos
Biodegradação Ambiental , Poluentes Ambientais/metabolismo , Marcação por Isótopo/métodos , Metagenômica/métodos , Carbono/metabolismo , Metagenômica/tendências , Filogenia
8.
Water Res ; 40(20): 3831-7, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17049581

RESUMO

While the US Environmental Protection Agency's (EPA) Beaches Environmental Assessment and Coastal Health (BEACH) Act requires coastal and Great Lakes' states to implement plans for monitoring bacterial contamination of recreational beach water, exactly how this monitoring should occur has not been regulated. This study examined differences in concentration of Escherichia coli in water collected from different depths and from different horizontal locations across the beach. E. coli concentrations were significantly different (p<0.05), when water from different depths was compared. Sampling water at depths of 30, 60, and 120 cm resulted in significantly lower E. coli concentrations as depth increased. Had the State of Wisconsin chosen to collect beach water monitoring samples at a shallower or deeper depth, numbers of beach closures and the potential risk to public health would have changed substantially. These data imply that a revised and standardized protocol for monitoring beach water should be adopted by all states of a monitoring region to better compare microbial contamination of beaches and protect public health.


Assuntos
Praias/normas , Monitoramento Ambiental/métodos , Escherichia coli/isolamento & purificação , Poluentes da Água/isolamento & purificação , Monitoramento Ambiental/normas , Água Doce , Michigan , Microbiologia da Água
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA