Anaerobic Enrichment Cultures Research Articles

Comparative Kinetics of Hydrogen Utilization for Reductive Dechlorination of Tetrachloroethene and Methanogenesis in an Anaerobic Enrichment Culture

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTComparative Kinetics of Hydrogen Utilization for Reductive Dechlorination of Tetrachloroethene and Methanogenesis in an Anaerobic Enrichment CultureConcordia R. Smatlak, James M. Gossett, and Stephen H. ZinderCite this: Environ. Sci. Technol. 1997, 31, 4, 1252Publication Date (Web):March 27, 1997Publication History Published online27 March 1997Published inissue 1 April 1997https://doi.org/10.1021/es962023cCopyright © 1997 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views277Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (26 KB) Get e-Alerts Get e-Alerts

Comment on “Comparative Kinetics of Hydrogen Utilization for Reductive Dechlorination of Tetrachloroethene and Methanogenesis in an Anaerobic Enrichment Culture”

Comment on “Comparative Kinetics of Hydrogen Utilization for Reductive Dechlorination of Tetrachloroethene and Methanogenesis in an Anaerobic Enrichment Culture”

Degradative capacities and 16S rRNA-targeted whole-cell hybridization of sulfate-reducing bacteria in an anaerobic enrichment culture utilizing alkylbenzenes from crude oil.

A mesophilic sulfate-reducing enrichment culture growing anaerobically on crude oil was used as a model system to study which nutritional types of sulfate-reducing bacteria may develop on original petroleum constituents in oil wells, tanks, and pipelines. Chemical analysis of oil hydrocarbons during growth revealed depletion of toluene and o-xylene within 1 month and of m-xylene, o-ethyltoluene, m-ethyltoluene, m-propyltoluene, and m-isopropyltoluene within approximately 2 months. In anaerobic counting series, the highest numbers of CFU (6 x 10(6) to 8 x 10(6) CFU ml-1) were obtained with toluene and benzoate. Almost the same numbers were obtained with lactate, a substrate often used for detection of the vibrio-shaped, incompletely oxidizing Desulfovibrio sp. In the present study, however, lactate yielded mostly colonies of oval to rod-shaped, completely oxidizing, sulfate-reducing bacteria which were able to grow slowly on toluene or crude oil. Desulfovibrio species were detected only at low numbers (3 x 10(5) CFU ml-1). In agreement with this finding, a fluorescently labeled, 16S rRNA-targeted oligonucleotide probe described in the literature as specific for members of the Desulfovibrionaceae (suggested family) hybridized only with a small portion (< 5%) of the cells in the enrichment culture. These results are consistent with the observation that known Desulfovibrio species do not utilize aromatic hydrocarbons, the predominant substrates in the enrichment culture. All known sulfate-reducing bacteria which utilize aromatic compounds belong to a separate branch, the Desulfobacteriaceae (suggested family). Most members of this family are complete oxidizers. For specific hybridization with members of this branch, the probe had to be modified by a nucleotide exchange. Indeed, this modified probe hybridized with more than 95% of the cells in the enrichment culture. The results show that completely oxidizing, alkylbenzene-utilizing sulfate-reducing bacteria rather than Desulfovibrio species have to be considered in attempts to understand the microbiology of sulfide production in oil wells, tanks, and pipelines when no electron donors other than the indigenous oil constituents are available.

Comparative Kinetics of Hydrogen Utilization for Reductive Dechlorination of Tetrachloroethene and Methanogenesis in an Anaerobic Enrichment Culture

Anaerobic microorganisms that reductively dechlorinate tetrachloroethene (PCE) must often compete with methanogens for H2. This study compared the kinetics of H2 utilization between the two types of organisms at 35 °C under conditions of continuous agitation. Limiting levels of H2 were administered to 160-mL serum bottles seeded with a PCE/butyric acid enrichment culture; H2, methane, and vinyl chloride were tracked over time using headspace samples. Measured half-velocity constants with respect to H2 Ks(H2) values ± 95% CIfor methanogenesis and dechlorination were 960 ± 180 and 100 ± 50 nM, respectively. Mass-transfer equations were used to calculate aqueous H2 concentrations at the half-velocity point from headspace measurements. The possible effect on Ks(H2) values arising from interconversion between H2 and formate through an active formate/H2 lyase system was examined by comparing results from formate-fed and H2-fed bottles. Only methanogens in the culture were apparently capable of using formate; he...

Biotransformation of α-, β-, γ-, and δ-Hexachlorocyclohexane under Methanogenic Conditions

During the production of the pesticide lindane (γ-hexachlorocyclohexane; γ-HCH), large quantities of byproducts, like the α-, β-, and δ-HCH isomers, were discarded at dump sites. β-HCH was found to be extremely persistent in the environment under aerobic conditions. We studied the degradation of this isomer under methanogenic conditions in a flow-through column packed with polluted sediment. β-HCH was completely removed in this system. Chlorobenzene was detected in the effluent as a product. A β-HCH transforming anaerobic enrichment culture was obtained in batch cultures by using the column material as inoculum. 6-2,3,4,5-Tetrachlorocyclohexene is proposed as an intermediate during transformation, while benzene and chlorobenzene were formed as stable end products. The enrichment culture was also able to dechlorinate α-HCH at a comparable rate and y- and 6-HCH at lower rates. Dechlorination was inhibited by the addition of vancomycin, but not by the addition of bromoethanesulfonic acid. Pasteurization inhibited dechlorination completely. This is the first detailed description of the biodegradation of β-HCH, including intermediate and end product identification, under defined anaerobic conditions.

Extremely thermophilic cellulolytic anaerobes from Icelandic hot springs.

Anaerobic enrichment cultures with Avicel as substrate and inoculated with biomat samples from Icelandic hot springs were cultured at 70 degrees C or 78 degrees C and examined for the presence of microorganisms that produce extracellular cellulolytic and xylanolytic enzymes. From four enrichments grown at 78 degrees C eighteen strains were isolated. Five of the strains were screened for their substrate utilization, and on the basis of differences in morphology and substrates used, the two most unique strains were selected for further characterization. All cellulolytic cultures were rod-shaped and non-sporeforming. Motility was not observed. Cells stained gram-negative at various stages of the growth phase. During growth on Avicel, most cultures produced acetate as the major fermentation product, with smaller amounts of lactic acid and ethanol. Carbon dioxide and hydrogen were also produced. The phenotypic characteristics of the enrichment cultures and of isolates are described and assessed in relation to temperature and pH in the hot spring environment. A comparison is made between Icelandic strains isolated in our laboratory and strains isolated from hot springs from other parts of the world. The biotechnological potential of this group of bacteria is briefly discussed.

Cobalamin-enhanced anaerobic biotransformation of carbon tetrachloride

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Characterization of an H2-utilizing enrichment culture that reductively dechlorinates tetrachloroethene to vinyl chloride and ethene in the absence of methanogenesis and acetogenesis.

We have been studying an anaerobic enrichment culture which, by using methanol as an electron donor, dechlorinates tetrachloroethene (PCE) to vinyl chloride and ethene. Our previous results indicated that H2 was the direct electron donor for rductive dechlorination of PCE by the methanol-PCE culture. Most-probable-number counts performed on this culture indicated low numbers (< or equal to 10(4)/ml)) of methanogens and PCE dechlorinators using methanol and high numbers (> or equal to 10(6)/ml)) of sulfidogens, methanol-utilizing acetogens, fermentative heterotrophs, and PCE dechlorinators using H2. An anaerobic H2-PCE enrichment culture was derived from a 10(-6) dilution of the methanol-PCE culture. This H2-PCE culture used PCE at increasing rates over time when transferred to fresh medium and could be transferred indefinitely with H2 as the electron donor for the PCE dechlorination, indicating that H2-PCE can serve as an electron donor-acceptor pair for energy conservation and growth. Sustained PCE dechlorination by this culture was supported by supplementation with 0.05 mg of vitamin B12 per liter, 25% (vol/vol) anaerobic digestor sludge supernatant, and 2 mM acetate, which presumably served as a carbon source. Neither methanol nor acetate could serve as an electron donor for dechlorination by the H2-PCE culture, and it did not produce CH4 or acetate from H2-CO2 or methanol, indicating the absence of methanogenic and acetogenic bacteria. Microscopic observatios of the pruified H2-PCE culture showed only two major morphotypes: irregular cocci and small rods.

Reductive dechlorination of tetrachloroethene by a high rate anaerobic microbial consortium.

Tetrachloroethene (PCE) and other chloroethenes are major contaminants in groundwater, and PCE is particularly resistant to attack by aerobes. We have developed an anaerobic enrichment culture that carries out reductive dechlorination of chloroethenes to ethene at high rates, thereby detoxifying them. Although the electron donor added to the culture is methanol, our evidence indicates that H2 is the electron donor used directly for dechlorination. We have recently obtained a culture from 10(-6) dilution of the original methanol/PCE culture that uses H2 as an electron donor for PCE dechlorination. Because the culture can be transferred indefinitely and the rate of PCE dechlorination increases after inoculation, we suggest that dechlorinating organisms in the culture use the carbon-chlorine bonds in chloroethenes as electron acceptors for energy conservation.

Rapid dehalogenation of 2,4,6-trichlorophenol at alkaline pH by an anaerobic enrichment culture

An enrichment culture, derived from the anaerobic stage of a two-step sequential anaerobic-aerobic reactor system which mineralized 2,4,6-trichlorophenol, stoichiometrically converted 2,4,6-trichlorophenol to 4-chlorophenol. Dehalogenation occurred only in alkaline media (pH 8-9) at concentrations of substrate up to 1 mmol 1 -1 . Formate plus acetate or trypticase could serve as electron donors. Neither vitamins nor trace elements were required in a chloride-free defined medium. The dehalogenating organism was oxygen-resistant, but was not active in media which were oxidized with respect to resazurin indicator dye. Most probable number counts of the dehalogenating cultures showed that the dehalogenating organisms were present in very small numbers, yet catalysed dehalogenation at rates considerably faster than other dehalogenating organisms described in the literature.

ｃｉｓ‐１，２‐ジクロロエチレン分解嫌気性集積培養菌の水素利用機構

cis-1,2-Dichloroethylene (cis-DCE) is frequently found as a groundwater contaminant. cis-DCE can be biotransformed via reductive dechlorination to ethylene under anaerobic conditions. We have recently reported a high-rate transformation of cis-DCE to ethylene by anaerobic enrichment cultures. A small part of ethylene was further reduced to ethane. Hydrogen appeared to be the actual electron donor for reductive transformation of cis-DCE in these cultures. In this study, batch experiments were conducted for investigating the mechanism of cis-DCE transformation by these anaerobic enrichment cultures. Hydrogen was used as an electron donor. Addition of 2-bromoethanesulfonate (BES), a specific inhibitor of methanogenesis, did not inhibit reductive dechlorination of cis-DCE. The major organisms utilizing hydrogen were not methanogens but homoacetogens. These results suggest that the dechlorinating organisms were homoacetogens. On the other hand, reduction of ethylene to ethane was inhibited in the presence of BES, suggesting a role of methanogens in this transformation.Batch experiments examining the biodegradability of tetrachloroethylene (PCE) by these cultures were also conducted and it was found that the cultures were able to transform PCE to ethylene at high rates.

Biodegradation of the nitroaromatic herbicide dinoseb (2-sec-butyl-4,6-dinitrophenol) under reducing conditions.

The degradation pathway for dinoseb (2-sec-butyl-4,6-dinitrophenol) under reducing conditions was investigated. Cultures were inoculated with a dinoseb-degrading anaerobic enrichment culture used in field studies. Biotransformation intermediates were extracted with ethyl acetate and analyzed by high pressure liquid chromatography, gas chromatography, and mass spectrometry. Dinoseb degradation involves reduction of the nitro groups to amino groups followed by replacement with hydroxyl groups. Depending on the pH and redox potential in the culture, these intermediates may exist as quinones or hydroquinones.

Anaerobic dechlorination of trichloroethene, tetrachloroethene and 1,2-dichloroethane by an acetogenic mixed culture in a fixed-bed reactor

An anaerobic enrichment culture with glucose as the sole source of carbon and energy plus trichloroethene (TCE) as a potential electron acceptor was inoculated with material from a full size anaerobic charcoal reactor that biologically eliminated dichloromethane from contaminated groundwater (Stromeyer et al. 1991). In subcultures of this enrichment complete sequential transformation of 10 microM TCE via cis-dichloroethene and chloroethene to ethene was reproducibly observed. Maintenance of this activity on subcultivation required the presence of TCE in the medium. The enrichment culture was used to inoculate an anaerobic fixed-bed reactor containing sintered glass Raschig elements as support material. The reactor had a total volume of 1780 ml and was operated at 20 degrees C in an up-flow mode with a flow rate of 50 ml/h. It was fed continuously with 2 mM glucose and 55 microM TCE. Glucose was converted to acetate as the major product and to a minor amount of methane; TCE was quantitatively dehalogenated to ethene. When, in addition to TCE, tetrachloroethene or 1,2-dichloroethane were added to the system, these compounds were also dehalogenated to ethene. In contrast, 1,1,1-trichloroethane was not dehalogenated, but at 40 microM severely inhibited acetogenesis and methanogenesis. When the concentration of TCE in the feed was raised to 220 microM, chloroethene transiently accumulated, but after an adaptation period ethene was again the only volatile product detected in the effluent. The volumetric degradation rate at this stage amounted to 6.2 mumol/l/h.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotransformation of cis-1,2-dichloroethylene to ethylene and ethane under anaerobic conditions

cis-1,2-Dichloroethylene (cis-DCE) is frequently found at significant concentrations in groundwater which is contaminated with tetrachloroethylene or trichloroethylene. Under anaerobic conditions, cis-DCE can be biotransformed via reductive dechlorination to ethylene. Several factors affecting this transformation were investigated using anaerobic sewage sludge as an inoculum. The reductive dechlorination of cis-DCE was observed at 25°C and 15°C but not at 35°C. Supplying a suitable electron donor (organic substrate or hydrogen) was necessary to sustain reductive dechlorination. Glucose, yeast extract, propionate, and hydrogen stimulated dechlorination, while methanol and acetate did not. Anaerobic enrichment cultures capable of dechlorinating cis-DCE to ethylene were developed from the sludge. In the presence of either glucose, yeast extract or propionate (100 mgCOD/l), 0.46 mg/l of cis-DCE was almost completely dechlorinated to ethylene within 4 days by the cultures at 25°C. Transformation rate was somewhat lower in the culture fed with hydrogen. Dechlorinating ability was sustained even in the cultures fed with low concentrations (10 mgCOD/l) of glucose or hydrogen, although the transformation was sometimes insufficient. These results suggest that anaerobic bioremediation processes can be used for removal of chlorinated ethylenes from contaminated groundwater.

Reductive Dehalogenation of Chlorinated Ethenes and Halogenated Ethanes by a High-Rate Anaerobic Enrichment Culture

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReductive Dehalogenation of Chlorinated Ethenes and Halogenated Ethanes by a High-Rate Anaerobic Enrichment CultureValter. Tandoi, Thomas D. DiStefano, Patrick A. Bowser, James M. Gossett, and Stephen H. ZinderCite this: Environ. Sci. Technol. 1994, 28, 5, 973–979Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://doi.org/10.1021/es00054a033RIGHTS & PERMISSIONSArticle Views708Altmetric-Citations122LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (838 KB) Get e-Alerts Get e-Alerts

Bioavailability of Chlorocatechols in Naturally Contaminated Sediment Samples and of Chloroguaiacols Covalently Bound to C 2 -Guaiacyl Residues

Bacteria in anaerobic enrichment cultures that dechlorinated a range of chlorocatechols were used to examine the stability of endogenous chlorocatechols in a contaminated sediment sample and in interstitial water prepared from it. During incubation of the sediment sample for 450 days with or without added cells, there was a decrease in the concentration of solvent-extractable chlorocatechols but not in that of the total chlorocatechols, including sediment-associated components. In the presence of azide, the decrease in the concentrations of the former was eliminated or substantially decreased. Control experiments in which 3,4,5-trichlorocatechol was added to the sediment suspensions after 130 days showed that its dechlorination was accomplished not only by the added cells but also by the endemic microbial flora. It was concluded that the endogenous chlorocatechols in the sediment were not accessible to microorganisms with dechlorinating activity. On the other hand, microorganisms were apparently responsible for decreasing the solvent extractability of the chlorocatechols, and this effect decreased with increasing length of exposure time. Similar experiments carried out for 70 days with the sediment interstitial water showed that the chlorocatechols that were known to be associated with organic matter were also inaccessible to microbial dechlorination. Experiments with model compounds in which 4,5,6-trichloroguaiacol and tetrachloroguaiacol were covalently linked to C(2)-guaiacyl residues showed that these compounds were resistant to O demethylation or dechlorination during incubation with a culture having these activities. The only effect of microbial action was the quantitative reduction in 12 days of the C'1 keto group to an alcohol which was stable against further transformation for up to 65 days. The results of these experiments are consistent with the existence of chlorocatechols and chloroguaiacols in contaminated sediments and illustrate the cardinal significance of bioavailability in determining their recalcitrance to dechlorination and O demethylation, respectively. It is suggested that bioavailability is an important factor in determining the persistence of xenobiotics in natural ecosystems and that its omission represents a serious limitation in the interpretation of many laboratory experiments directed towards determining the persistence of xenobiotics in aquatic ecosystems.

Reduction of perchlorate by an anaerobic enrichment culture

A mixed bacterial culture capable of reducing perchlorate stoichiometrically to chloride under naerobic conditions was enriched from municipal digester sludge. The reduction of 10 mM perchlorate resulted in oxidation of the medium and cessation of perchlorate reduction. The activity was recovered on addition of a reducing agent. Addition of air to the culture during perchlorate reduction immediately terminated the process and aeration for 12 h permanently destroyed the ability of the culture to reduce perchlorate. The culture also reduced nitrite, nitrate, chlorite, chlorate and sulfate. The presence of 10 mM nitrite or chlorite completely inhibited perchlorate reduction, whereas the same concentration of chlorate decreased the reduction rate. Nitrate or sulfate did not affect perchlorate reduction. Chlorate and chlorite, suspected intermediates in the reduction of perchlorate to chloride, were not detected in any cultures during reduction of perchlorate.

Urea production by Thiosphaera pantotropha and by anaerobic enrichment cultures from marine sediments

Urea production by Thiosphaera pantotropha and by anaerobic enrichment cultures from marine sediments

Urea production by Thiosphaera pantotropha and by anaerobic enrichment cultures from marine sediments

The production of urea by Thiosphaera pantotropha was studied. Batch cultures were grown on acetate as energy source and with NO3− or O2 as terminal electron acceptor. Urea accumulated in the media during exponential growth in aerobic and anaerobic cultures of T. pantotropha. Urea production continued after the cells had entered the stationary growth phase. Bacterial ability to produce urea was supported by studies of cultures enriched for denitrifying, sulphate-reducing and fermenting bacteria. The results implied that urea production was common among bacteria normally considered to be important in marine sediments.

Determination of tetrathionate and thiosulfate in natural samples and microbial cultures by a new, fast and sensitive ion chromatographic technique

A new isocratic ion chromatographic technique is described for the sensitive measurement of tetrathionate, trithionate and thiosulfate. The sulfur oxyanions were separated on a polymer-coated, silica-based anion exchange column and directly detected by UV absorption at 216 nm. Aqueous saline acetonitrile/methanol mixtures were used as eluent. The three anions could be quantified in less than 10 min with detection limits of about 0.6 pmol for tetrathionate and of 40 and 10 pmol for trithionate and thiosulfate, respectively. The retention times of tetrathionate responded to changes of the solvent concentration, whereas the elution of thiosulfate depended predominatly on the ionic strenght of the eluent. Starting at the lowest detectable concentrations, calibration curves for all three compounds were linear over a concentration range of three orders of magnitude. The analysis of freshwater and saline samples worked equally well. Since contact of the eluent with metallic components caused shifts in retention times during operation, the solvent delivery system had to consist of plastic material. Examples of applicaton are given for determination of tetrathionate and thiosulfate in natural samples and for the turnover of these two compounds in sediment slurries and anaerobic enrichment cultures.