scholarly journals Reductive Dechlorination of Tetrachloroethene tocis-1,2-Dichloroethene by a Thermophilic Anaerobic Enrichment Culture

1999 ◽  
Vol 65 (6) ◽  
pp. 2312-2316 ◽  
Author(s):  
Servé W. M. Kengen ◽  
Caroline G. Breidenbach ◽  
Andreas Felske ◽  
Alfons J. M. Stams ◽  
Gosse Schraa ◽  
...  
Keyword(s):  
Molecular Analysis ◽  
Electron Acceptor ◽  
Reductive Dechlorination ◽  
Dominant Species ◽  
Enrichment Culture ◽  
Microscopic Analysis ◽  
Dry Weight ◽  
Anaerobic Biodegradation ◽  
Optimum Temperature ◽  
Grown Culture

ABSTRACT Thermophilic anaerobic biodegradation of tetrachloroethene (PCE) was investigated with various inocula from geothermal and nongeothermal areas. Only polluted harbor sediment resulted in a stable enrichment culture that converted PCE via trichloroethene tocis-1,2-dichloroethene at the optimum temperature of 60 to 65°C. After several transfers, methanogens were eliminated from the culture. Dechlorination was supported by lactate, pyruvate, fructose, fumarate, and malate as electron donor but not by H2, formate, or acetate. Fumarate and l-malate led to the highest dechlorination rate. In the absence of PCE, fumarate was fermented to acetate, H2, CO2, and succinate. With PCE, less H2 was formed, suggesting that PCE competed for the reducing equivalents leading to H2. PCE dechlorination, apparently, was not outcompeted by fumarate as electron acceptor. At the optimum dissolved PCE concentration of ∼60 μM, a high dechlorination rate of 1.1 μmol h−1mg−1 (dry weight) was found, which indicates that the dechlorination is not a cometabolic activity. Microscopic analysis of the fumarate-grown culture showed the dominance of a long thin rod. Molecular analysis, however, indicated the presence of two dominant species, both belonging to the low-G+C gram positives. The highest similarity was found with the genus Dehalobacter (90%), represented by the halorespiring organism Dehalobacter restrictus, and with the genus Desulfotomaculum(86%).

scholarly journals Comparison of Energy and Growth Yields forDesulfitobacterium dehalogenans during Utilization of Chlorophenol and Various Traditional Electron Acceptors

1998 ◽  
Vol 64 (1) ◽  
pp. 352-355 ◽  
Author(s):  
M. Mackiewicz ◽  
J. Wiegel
Keyword(s):  
Electron Donor ◽  
Electron Acceptor ◽  
Reductive Dechlorination ◽  
Dry Weight ◽  
Electron Acceptors ◽  
Growth Yields ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor

ABSTRACT Desulfitobacterium dehalogenans grew with formate as the electron donor and 3-chloro-4-hydroxyphenylacetate (3-Cl-4-OHPA) as the electron acceptor, yielding Y X/formate,Y X/2e− , andY X/ATP ranging from 3.2 to 11.3 g of biomass (dry weight)/mol, thus indicating that energy was conserved through reductive dechlorination. Pyruvate was utilized as the electron donor and acceptor, yielding stoichiometric amounts of acetate and lactate, respectively, and a Y X/reduced acceptor of 13.0 g of biomass (dry weight)/mol. The supplementation of pyruvate-containing medium with additional electron acceptors, such as 3-Cl-4-OHPA, nitrate, fumarate, or sulfite, caused pyruvate to be replaced as the electron acceptor and nearly doubled theY X/ATP (Y X/acetate formed). A comparison of the yields for 3-Cl-4-OHPA with those for other traditional electron acceptors indicates that the dehalogenation reaction led to the formation of similar amounts of energy equivalents. The various electron acceptors were used concomitantly with 3-Cl-4-OHPA in nonacclimated cultures, but the utilization rates and amounts utilized differed.

scholarly journals Anaerobic biodegradation of chloroform and dichloromethane with a Dehalobacter enrichment culture

2021 ◽  
Author(s):  
Hao Wang ◽  
Rong Yu ◽  
Jennifer Webb ◽  
Peter Dollar ◽  
David L Freedman
Keyword(s):  
Organic Acids ◽  
Electron Donor ◽  
Reductive Dechlorination ◽  
Enrichment Culture ◽  
Reducing Power ◽  
Anaerobic Biodegradation ◽  
Anaerobic Conditions ◽  
Aliphatic Compounds ◽  
Predominant Product ◽  
Complete Dechlorination

Chloroform (CF) and dichloromethane (DCM) are among the more commonly identified chlorinated aliphatic compounds found in contaminated soil and groundwater. Complete dechlorination of CF has been reported under anaerobic conditions by microbes that respire CF to DCM and others that biodegrade DCM. The objectives of this study were to ascertain if a commercially available bioaugmentation enrichment culture (KB-1® Plus) uses an oxidative or fermentative pathway for biodegradation of DCM; and to determine if the products from DCM biodegradation can support organohalide respiration of CF to DCM in the absence of an exogenous electron donor. In various treatments with the KB-1® Plus culture to which 14C-CF was added, the predominant product was 14CO2, indicating that oxidation is the predominant  pathway for DCM. Recovery of 14C-DCM when biodegradation was still in progress confirmed that CF first undergoes reductive dechlorination to DCM. 14C-labeled organic acids, including acetate and propionate, were also recovered, suggesting that synthesis of organic acids provides a sink for the electron equivalents from oxidation of DCM. When the culture was washed to remove organic acids from prior additions of exogenous electron donor and only CF and DCM were added, the culture completely dechlorinated CF. The total amount of DCM added was not sufficient to provide the electron equivalents needed to reduce CF to DCM. Thus, the additional reducing power came via the DCM generated from CF reduction. Nevertheless, the rate of CF consumption was considerably slower in comparison to treatments that received an exogenous electron donor.

Enrichment and characterization of an anaerobic methyl ethyl ketoxime degrading culture from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor

1998 ◽  
Vol 37 (4-5) ◽  
pp. 95-98 ◽  
Author(s):  
Nancy G. Love ◽  
Mary E. Rust ◽  
Kathy C. Terlesky
Keyword(s):  
Energy Source ◽  
Activated Sludge ◽  
Electron Acceptor ◽  
Sequencing Batch Reactor ◽  
Enrichment Culture ◽  
Batch Reactor ◽  
Nitrification Inhibitor ◽  
Time Frame ◽  
Methyl Ethyl

An anaerobic enrichment culture was developed from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor using methyl ethyl ketoxime (MEKO), a potent nitrification inhibitor, as the sole carbon and energy source in the absence of molecular oxygen and nitrate. The enrichment culture was gradually fed decreasing amounts of biogenic organic compounds and increasing concentrations of MEKO over 23 days until the cultures metabolized the oxime as the sole carbon source; the cultures were maintained for an additional 41 days on MEKO alone. Turbidity stabilized at approximately 100 mg/l total suspended solids. Growth on selective media plates confirmed that the microorganisms were utilizing the MEKO as the sole carbon and energy source. The time frame required for growth indicated that the kinetics for MEKO degradation are slow. A batch test indicated that dissolved organic carbon decreased at a rate comparable to MEKO consumption, while sulfate was not consumed. The nature of the electron acceptor in anaerobic MEKO metabolism is unclear, but it is hypothesized that the MEKO is hydrolyzed intracellularly to form methyl ethyl ketone and hydroxylamine which serve as electron donor and electron acceptor, respectively.

Biotransformation of nitrocellulose under methanogenic conditions

1996 ◽  
Vol 34 (5-6) ◽  
pp. 327-334 ◽  
Author(s):  
David L. Freedman ◽  
Bryan M. Caenepeel ◽  
Byung J. Kim
Keyword(s):  
Biological Treatment ◽  
Enrichment Culture ◽  
Basal Medium ◽  
Anaerobic Biodegradation ◽  
Anaerobic Treatment ◽  
Acid Digestion ◽  
Energetic Compounds ◽  
Nitrate Ester ◽  
Digestion Technique ◽  
Aerobic And Anaerobic

Treatment of wastewater containing nitrocellulose (NC) fines is a significant hazardous waste problem currently facing manufacturers of energetic compounds. Previous studies have ruled out the use of biological treatment, since NC has appeared to be resistant to aerobic and anaerobic biodegradation. The objective of this study was to examine NC biotransformation in a mixed methanogenic enrichment culture. A modified cold-acid digestion technique was used to measure the percentage of oxidized nitrogen (N) remaining on the NC. After 11 days of incubation in cultures amended with NC (10 g/L) and methanol (9.9 mM), the % N (w/w) on the NC decreased from 13.3% to 10.1%. The presence of NC also caused a 16% reduction in methane output. Assuming the nitrate ester on NC was reduced to N2, the decrease in CH4 represented almost exactly the amount of reducing equivalents needed for the observed decrease in oxidized N. An increase in the heat of combustion of the transformed NC correlated with the decrease in % N. There was no statistically significant decrease in % N when only NC was added to the culture, or in controls that contained only the sulfide-reduced basal medium. The biotransformed NC has a % N comparable to nonexplosive nitrated celluloses, suggesting that anaerobic treatment may be a technically feasible process for rendering NC nonhazardous.

Temperature dependence of germinability of wheat (Triticum aestivum L.) grain in relation to pre-harvest sprouting

1984 ◽  
Vol 35 (2) ◽  
pp. 115 ◽  
Author(s):  
DJ Mares
Keyword(s):  
Dry Weight ◽  
Complete Removal ◽  
Triticum Aestivum L ◽  
Treatment Temperature ◽  
Preharvest Sprouting ◽  
Optimum Temperature ◽  
Grain Dormancy ◽  
Lag Period ◽  
Pre Treatment ◽  
Damage Tolerant

Germinability in harvest-mature wheat grain showed a marked dependence on temperature. The optimum temperature for the complete germination of all grains ranged from 20�C for the non-dormant variety, Timgalen, to 10�C for the strongly dormant red wheat RL 4137, whereas the optimum in terms of the shortest lag period ranged from 25� to 15�C for the same varieties. Germinability gradually increased during post-harvest storage and, for after-ripened grain, the optimum temperature for both complete germination and shortest lag period were greater than 30�C. Germinability could also be increased by pre-treating imbibing grains at temperatures of 5�, 10� or in some cases 15�C. This treatment was only effective for grain at moisture contents >25% (dry weight) and the effect was not reversed by redesiccation. The pre-treatment temperature required for maximum germinability decreased with increasing levels of grain dormancy. Complete removal of dormancy required a pre-treatment period of c. 48 h; however, lesser periods gave the shortest lag period in the case of the dormant varieties. The implications of these results for the utilization of dormancy in the development of preharvest sprouting damage tolerant varieties and their subsequent use in practice are discussed.

Anaerobic biodegradation of trimethoprim with sulfate as an electron acceptor

2019 ◽  
Vol 13 (6) ◽  
Author(s):  
Bin Liang ◽  
Deyong Kong ◽  
Mengyuan Qi ◽  
Hui Yun ◽  
Zhiling Li ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Anaerobic Biodegradation

Growth of Odontia bicolor in vitro

1970 ◽  
Vol 48 (3) ◽  
pp. 447-452
Author(s):  
Denis Lachance
Keyword(s):  
Mineral Soil ◽  
Dry Weight ◽  
Organic Soil ◽  
Balsam Fir ◽  
Natural Soil ◽  
Malt Extract ◽  
Optimum Temperature ◽  
Extract Medium ◽  
Mycelial Strands

The growth of Odontia bicolor in soil and in balsam fir wood was studied. In steam-sterilized organic soil, the fungus grows rapidly, producing a scanty and uniform growth, whereas in propylene oxide gas-treated or natural organic soil, it forms mycelial strands. In mineral soil, the fungus reacts as in organic soil except that growth is more sparse. The fungus grows through natural soil and colonizes new substrate more rapidly when mycelial strands are linked to an appropriate food base.The optimum temperature for growth on a 2.5% malt extract medium occurs between 22 and 27 °C. The fungus grows well in balsam fir wood at any moisture content above 42% of the oven-dry weight, and twice as fast in sapwood as in heartwood. Its growth is not influenced by previous storage of the wood, either frozen (−20 °C) or at a temperature of 2 °C for up to 16 weeks.

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