Substrate interactions during aerobic biodegradation of methane, ethene, vinyl chloride and 1,2-dichloroethenes

2001 ◽  
Vol 43 (5) ◽  
pp. 333-340 ◽  
Author(s):  
D. L. Freedman ◽  
A. S. Danko ◽  
M. F. Verce
Keyword(s):  
Vinyl Chloride ◽  
Natural Attenuation ◽  
Enrichment Culture ◽  
Active Role ◽  
Aerobic Biodegradation ◽  
Aerobic Conditions ◽  
Lag Period ◽  
Anaerobic Zone ◽  
Set Up ◽  
Cis And Trans

Intrinsic biodegradation of trichloroethene and 1,1,1-trichloroethane in groundwater at a Superfund site in California has been observed. An anaerobic zone exists in the area closest to the source location, yielding the expected complement of reductive dechlorination daughter products, including cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC). Significant levels of methane and ethene were also generated in the anaerobic zone. The groundwater returns to aerobic conditions downgradient of the source, with methane, ethene, VC, and several other compounds still present. Attenuation of VC in the aerobic zone suggests that it is being biodegraded. In this study microcosms were used to evaluate the role of methane and ethene as primary substrates for aerobic biodegradation of VC. Biodegradation of VC was fastest in the bottles containing ethene, with 40 μmol of VC consumed over a 150 day period, compared to approximately 15–20 μmol with methane or a mixture of methane and ethene. VC did not noticeably inhibit ethene biodegradation but did slow the rate of methane use. Methane inhibited ethene metabolism, which apparently caused a reduction in VC biodegradation when methane was present with ethene. These results suggest that ethene plays an important role during in situ natural attenuation of VC under aerobic conditions. Microcosms were also set up with VC alone. Following a 75 day lag period, VC consumption began and subsequent additions were consumed without a lag, suggesting the presence of organisms capable of using VC as a growth substrate. After providing VC alone for nearly 400 days, aliquots of the enrichment culture were used to evaluate its ability to biodegrade cis- and trans-DCE. Both compounds were readily consumed, although addition of VC as the primary substrate was needed to sustain biodegradation of repeated additions. This result suggests that organisms capable of using VC as a sole substrate may play an active role in aerobic natural attenuation of DCEs.

Robustness of an aerobic metabolically vinyl chloride degrading bacterial enrichment culture

2011 ◽  
Vol 64 (9) ◽  
pp. 1796-1803 ◽  
Author(s):  
He-Ping Zhao ◽  
Kathrin R. Schmidt ◽  
Svenja Lohner ◽  
Andreas Tiehm
Keyword(s):  
Vinyl Chloride ◽  
Natural Attenuation ◽  
Enrichment Culture ◽  
Contaminated Sites ◽  
Contaminated Groundwater ◽  
Chlorinated Ethene ◽  
Equimolar Concentration ◽  
Bacterial Enrichment ◽  
Ph Tolerance

Degradation of the lower chlorinated ethenes is crucial to the application of natural attenuation or in situ bioremediation on chlorinated ethene contaminated sites. Recently, within mixtures of several chloroethenes as they can occur in contaminated groundwater inhibiting effects on aerobic chloroethene degradation have been shown. The current study demonstrated that metabolic vinyl chloride (VC) degradation by an enrichment culture originating from groundwater was not affected by an equimolar concentration (50 μM) of cis-1,2-dichloroethene (cDCE). Only cDCE concentrations at a ratio of 2.4:1 (initial cDCE to VC concentration) caused minor inhibition of VC degradation. Furthermore, the degradation of VC was not affected by the presence of trans-1,2-dichloroethene (tDCE), 1,1-dichloroethene (1,1-DCE), trichloroethene (TCE), and tetrachloroethene (PCE) in equimolar concentrations (50 μM). Only cDCE and tDCE were cometabolically degraded in small amounts. The VC-degrading culture demonstrated a broad pH tolerance from 5 to 9 with an optimum between 6 and 7. Results also showed that the culture could degrade VC concentrations up to 1,800 μM (110 mg/L).

scholarly journals Characterization of an Isolate That Uses Vinyl Chloride as a Growth Substrate under Aerobic Conditions

2000 ◽  
Vol 66 (8) ◽  
pp. 3535-3542 ◽  
Author(s):  
Matthew F. Verce ◽  
Ricky L. Ulrich ◽  
David L. Freedman
Keyword(s):  
Vinyl Chloride ◽  
Suspended Solids ◽  
Specific Growth ◽  
Enrichment Culture ◽  
Initial Step ◽  
Aerobic Biodegradation ◽  
Utilization Rate ◽  
Rrna Gene ◽  
Donor Source

ABSTRACT An aerobic enrichment culture was developed by using vinyl chloride (VC) as the sole organic carbon and electron donor source. VC concentrations as high as 7.3 mM were biodegraded without apparent inhibition. VC use did not occur when nitrate was provided as the electron acceptor. A gram-negative, rod-shaped, motile isolate was obtained from the enrichment culture and identified based on biochemical characteristics and the sequence of its 16S rRNA gene asPseudomonas aeruginosa, designated strain MF1. The observed yield of MF1 when it was grown on VC was 0.20 mg of total suspended solids (TSS)/mg of VC. Ethene, acetate, glyoxylate, and glycolate also served as growth substrates, while ethane, chloroacetate, glycolaldehyde, and phenol did not. Stoichiometric release of chloride and minimal accumulation of soluble metabolites following VC consumption indicated that the predominant fate for VC is mineralization and incorporation into cell material. MF1 resumed consumption of VC after at least 24 days when none was provided, unlike various mycobacteria that lost their VC-degrading ability after brief periods in the absence of VC. When deprived of oxygen for 2.5 days, MF1 did not regain the ability to grow on VC, and a portion of the VC was transformed into VC-epoxide. Acetylene inhibited VC consumption by MF1, suggesting the involvement of a monooxygenase in the initial step of VC metabolism. The maximum specific VC utilization rate for MF1 was 0.41 μmol of VC/mg of TSS/day, the maximum specific growth rate was 0.0048/day, and the Monod half-saturation coefficient was 0.26 μM. A higher yield and faster kinetics occurred when MF1 grew on ethene. When grown on ethene, MF1 was able to switch to VC as a substrate without a lag. It therefore appears feasible to grow MF1 on a nontoxic substrate and then apply it to environments that do not exhibit a capacity for aerobic biodegradation of VC.

The Role of Higher Education in Developing Effective Support Structures for Technology Entrepreneurs

1997 ◽  
Vol 11 (4) ◽  
pp. 204-210
Author(s):  
Gerry Carroll ◽  
Colette Henry
Keyword(s):  
Technical College ◽  
Technological Development ◽  
Active Role ◽  
Technology Support ◽  
Support Structure ◽  
North East ◽  
The North ◽  
Set Up ◽  
Level Institution ◽  
Support Facility

The authors examine the active role which a third-level institution in the North East of Ireland has taken in the development of a regional support structure for new and existing technology-based businesses. The specific experiences of Dundalk Regional Technical College (Dundalk RTC) are related and their response to the new RTC Act is described. The paper focuses on the technological aspect of the new regional development role and describes how the College's incubator was set up and developed into a comprehensive support facility for technology-based businesses. The main objective of the paper is to identify the key components of an effective technology support structure. The advantages of a campus-based support facility are underlined, as is the need for a comprehensive approach to regional technological development.

scholarly journals En dynamisk kulturarv – Dybbøls 12 metamorfoser

1970 ◽  
pp. 55
Author(s):  
Inge Andriansen
Keyword(s):  
Cultural Heritage ◽  
Cultural Landscape ◽  
Local Population ◽  
Active Role ◽  
Large Mass ◽  
Mass Graves ◽  
North East ◽  
The World ◽  
Set Up ◽  
The Many

Dybbøl is the brow of a hill located about 30 km north-east of the border between Denmark and Germany. This area was once the former Danish Duchy of Schleswig, which was under German rule in the period from 1864 to 1920. Dybbøl was also the site of intense fighting during the Schleswig-Holstein Revolt of 1848–50 and the Danish-German War of 1864. There are remains of both Danish and German fortifications and earthworks, along with large mass graves in which troops from Denmark, Schleswig-Holstein and Germany lie buried. After a plebiscite about the placing of the border was held in 1920, Schleswig was divided up, and the northern part – which included Dybbøl – became part of Denmark. This was followed by a comprehensive ”Danishification” of the cultural landscape, which had previously been dominated by a large Prussian victory monument and numerous German memorial stones. A Danish national park was set up at Dybbøl in 1924, with the backing of the local population and financial sup- port from a national collection appeal, and formally opened by the Danish prime minister. After this, Dybbøl became the epitome of the institutionalised cultural heritage of the state of Denmark, and would almost certainly be included in any ”cultural canon” of the most significant geographical locations that have helped shape the Danish sense of national identity. However, Dybbøl also features another – less comfortable – aspect of the Danish cultural heritage, bearing witness to Danish acts of vandalism perpetrated against the German monuments found here. Any study of the use of the history associated with Dybbøl uncovers layer upon layer of episodes that speak of conflicting interests and countless metamorphoses that led to the site being imbued with new values and a sequence of new identities. And in step with the resurgence of nationalist sentiments in Denmark since the mid-1980s, there has been a corresponding, strengthened re-annexation of the cultural heritage associated with Dybbøl. The need to cling on to and retain establis- hed, familiar positions and a fundamental sense of belonging are well-known aspects of the process of globalisation, and are seen throughout the world. In Dybbøl, this deep-felt need has resulted in the construction of a Danish fortification, and the Danish flag flying atop the many flagpoles has become more frequent sight. This process can also be interpreted as an expression of Danish foreign policy taking on a more active role in the world.

Aerobic biodegradation of vinyl chloride and cis-1,2-dichloroethylene in aquifer sediments

Chemosphere ◽  
2005 ◽  
Vol 60 (11) ◽  
pp. 1555-1564 ◽  
Author(s):  
Kim Broholm ◽  
Liselotte Ludvigsen ◽  
Thorkild Feldthusen Jensen ◽  
Henrik Østergaard
Keyword(s):  
Vinyl Chloride ◽  
Aerobic Biodegradation ◽  
Aquifer Sediments

Sequential anaerobic/aerobic biodegradation of chlorinated hydrocarbons in activated carbon barriers

2002 ◽  
Vol 2 (2) ◽  
pp. 51-58 ◽  
Author(s):  
A. Tiehm ◽  
M. Gozan ◽  
A. Müller ◽  
H. Schell ◽  
H. Lorbeer ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Biological Activity ◽  
Activated Carbon ◽  
Vinyl Chloride ◽  
Reductive Dechlorination ◽  
Chlorinated Hydrocarbons ◽  
Aerobic Biodegradation ◽  
Anaerobic Conditions ◽  
Biological Activated Carbon ◽  
Batch Tests

The aim of this study is to develop a long lasting, sequential anaerobic/aerobic biological activated carbon barrier. In the biobarrier, pollutant adsorption on granular activated carbon (GAC) and biodegradation occur simultaneously. Trichloroethene (TCE), chlorobenzene (CB), and benzene were used as model pollutants. In the first barrier, that was operated under anaerobic conditions with sucrose and ethanol as auxiliary substrates, TCE was completely converted to lower chlorinated metabolites, predominantly cis-dichloroethene (cis-DCE). The reductive dechlorination process was stable for about 300 d, although the concomitant sulphate-reducing and methanogenic processes varied considerably. In the second barrier, that was operated with addition of hydrogen peroxide and nitrate, dechlorination was limited by a lack of oxygen and restricted mainly to CB biodegradation. Additional aerobic batch tests revealed that the metabolites of anaerobic TCE dechlorination, i.e. cis-DCE and vinyl chloride, were oxidatively dechlorinated in the presence of suitable auxiliary substrates such as ethene, CB, benzene, or sucrose and ethanol. During periods of low biological activity, elimination of TCE and CB occurred by adsorption in the GAC barriers. The pre-sorbed pollutants were available for subsequent biodegradation resulting in a bioregeneration of the activated carbon barriers.

scholarly journals Oxidative Stress and NO Signalling in the Root Apex as an Early Response to Changes in Gravity Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Sergio Mugnai ◽  
Camilla Pandolfi ◽  
Elisa Masi ◽  
Elisa Azzarello ◽  
Emanuela Monetti ◽  
...  
Keyword(s):  
Transition Zone ◽  
Root Apex ◽  
Active Role ◽  
Early Response ◽  
Real Microgravity ◽  
Microgravity Conditions ◽  
Auxin Redistribution ◽  
Set Up ◽  
No Fluxes

Oxygen influx showed an asymmetry in the transition zone of the root apex when roots were placed horizontally on ground. The influx increased only in the upper side, while no changes were detected in the division and in the elongation zone. Nitric oxide (NO) was also monitored after gravistimulation, revealing a sudden burst only in the transition zone. In order to confirm these results in real microgravity conditions, experiments have been set up by using parabolic flights and drop tower. The production of reactive oxygen species (ROS) was also monitored. Oxygen, NO, and ROS were continuously monitored during normal and hyper- and microgravity conditions in roots of maize seedlings. A distinct signal in oxygen and NO fluxes was clearly detected only in the apex zone during microgravity, with no significant changes in normal and in hypergravity conditions. The same results were obtained by ROS measurement. The detrimental effect of D’orenone, disrupting the polarised auxin transport, on the onset of the oxygen peaks during the microgravity period was also evaluated. Results indicates an active role of NO and ROS as messengers during the gravitropic response, with probable implications in the auxin redistribution.

Mechanism controlling the extended lag period associated with vinyl chloride starvation in Nocardioides sp. strain JS614

2006 ◽  
Vol 187 (3) ◽  
pp. 217-226 ◽  
Author(s):  
Timothy E. Mattes ◽  
Nicholas V. Coleman ◽  
Adina S. Chuang ◽  
Andrea J. Rogers ◽  
Jim C. Spain ◽  
...  
Keyword(s):  
Vinyl Chloride ◽  
Lag Period

The sorption and degradation of the rice pesticides fipronil and thiobencarb on two Australian rice soils

Soil Research ◽  
2006 ◽  
Vol 44 (6) ◽  
pp. 599 ◽  
Author(s):  
Gregory Doran ◽  
Philip Eberbach ◽  
Stuart Helliwell
Keyword(s):  
Organic Carbon ◽  
Absolute Amount ◽  
Anaerobic Conditions ◽  
Rice Soils ◽  
Aerobic Conditions ◽  
Soil Microbial ◽  
Layer Analysis ◽  
Lag Period ◽  
The Difference ◽  
Soil Microbial Population

The sorption and degradation of the rice pesticides fipronil and thiobencarb on 2 Australian rice-growing soils were investigated. Greater sorption of both pesticides occurred on the soil containing less organic carbon, possibly as a result of the type of organic carbon present, rather than the absolute amount. While sorption tended to appear greater in the 0–10 mm layer than the 10–20 mm layer, analysis showed the difference was not significant (P > 0.05). Under aerobic conditions, a lag period of 20 days in the degradation of thiobencarb occurred on the Yanco soil, but rapid degradation occurred on the Coleambally soil, and, while unlikely, may have been a consequence of preconditioning of the Coleambally soil microbial population. Degradation of thiobencarb under both non-flooded anaerobic and flooded anaerobic conditions differed significantly (P < 0.05) compared to aerobic conditions. Conversely, fipronil degraded rapidly over the first few days and then slowed, and was attributed to the co-metabolism of fipronil by soil microbes. While fipronil sulfide was produced under all oxic/anoxic conditions, its concentration was greatest under flooded anaerobic conditions, possibly as a result of greater exclusion of oxygen from the soil by the floodwater.

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