0786 - Metagenomic analysis of anaerobic phenanthrene-degradation by a bacterial enrichment culture

ABSTRACT We sequenced the metagenome of a microbial community enriched under strictly anaerobic conditions from wastewater treatment plant-derived digester sludge. The metagenomic analysis of the enrichment revealed that Acetobacterium and methanogenic archaea belonged to the dominant prokaryotes, and genes encoding components of the Wood-Ljungdahl pathway were identified.

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Robustness of an aerobic metabolically vinyl chloride degrading bacterial enrichment culture

Water Science & Technology ◽

10.2166/wst.2011.752 ◽

2011 ◽

Vol 64 (9) ◽

pp. 1796-1803 ◽

Cited By ~ 3

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).

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Biodegradation of munitions compounds by a sulfate reducing bacterial enrichment culture

10.2172/515534 ◽

1997 ◽

Author(s):

R. Boopathy ◽

J. Manning

Keyword(s):

Enrichment Culture ◽

Sulfate Reducing ◽

Bacterial Enrichment

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Comparative physiology of phenanthrene degradation by two dissimilar pseudomonads isolated from a creosote-contaminated soil

Canadian Journal of Microbiology ◽

10.1139/m94-071 ◽

1994 ◽

Vol 40 (6) ◽

pp. 432-438 ◽

Cited By ~ 37

Author(s):

William T. Stringfellow ◽

Michael D. Aitken

Keyword(s):

Contaminated Soil ◽

Genetic Relatedness ◽

Enrichment Culture ◽

Acid Methyl Ester ◽

Pseudomonas Stutzeri ◽

Maximum Activity ◽

Resting Cells ◽

Phenanthrene Degradation ◽

Naphthoic Acid ◽

P 16

Two species of bacteria, identified as Pseudomonas stutzeri (P-16) and Pseudomonas saccharophila (P-15) by fatty acid methyl ester analysis, were found in a phenanthrene enrichment culture of a creosote-contaminated soil. The organisms are shown to be physiologically dissimilar, and their genetic relatedness is discussed. Phenanthrene degradation by both organisms followed Michaelis–Menten kinetics, allowing for the determination of half-saturation (Ks) and maximum activity coefficients, using nonlinear regression. Both organisms utilized kinetically similar enzymes for phenanthrene uptake and oxidation, as evidenced by similar Ks coefficients of approximately 0.2 mg/L and temperature optima of 40 °C, but levels of expression differed with different media. Each organism degraded phenanthrene via salicylic acid, but patterns of intermediate metabolism were shown to differ. P-15 excreted 1-hydroxy-2-naphthoic acid during growth on phenanthrene and demonstrated Michaelis–Menten kinetics for the oxidation of 1-hydroxy-2-naphthoic acid by resting cells. P-16 excreted only trace amounts of 1-hydroxy-2-naphthoic acid and demonstrated linear kinetics in response to 1-hydroxy-2-naphthoic acid concentration. P-15 was found to form thick biofilms on phenanthrene crystals and was characterized by a hydrophobic cell surface, whereas P-16 grew mostly in suspension and was hydrophilic. Neither organism produced significant amounts of biosurfactants when grown on phenanthrene. The implications of these findings for the design of systems to remediate contaminated soil are discussed.Key words: phenanthrene, 1-hydroxy-2-naphthoic acid, biodegradation, kinetics, polycyclic aromatic hydrocarbons.

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Bacteriophages May Bias Outcome of Bacterial Enrichment Cultures

Applied and Environmental Microbiology ◽

10.1128/aem.71.8.4269-4275.2005 ◽

2005 ◽

Vol 71 (8) ◽

pp. 4269-4275 ◽

Cited By ~ 28

Author(s):

Maite Muniesa ◽

Anicet R. Blanch ◽

Francisco Lucena ◽

Juan Jofre

Keyword(s):

Growth Rates ◽

Enrichment Culture ◽

Inhibitory Effects ◽

Relative Growth ◽

Relative Growth Rates ◽

Bacterial Enrichment ◽

Enrichment Cultures ◽

Natural Settings ◽

Microbial Systems ◽

Enrichment Step

ABSTRACT Enrichment cultures are widely used for the isolation of bacteria in clinical, biotechnological, and environmental studies. However, competition, relative growth rates, or inhibitory effects may alter the outcome of enrichment cultures, causing the phenomenon known as enrichment bias. Bacteriophages are a major component in many microbial systems, and it abounds in natural settings. This abundance means that bacteriophages are likely to be present in many laboratory enrichment cultures. Our hypothesis was that bacteriophages present in the sample might bias the enriched subpopulation, since it can infect and lyse the target bacteria during the enrichment step once the bacteria reach a given density. Here we show that the presence of bacteriophages in Salmonella and Shigella enrichment cultures produced a significant reduction (more than 1 log unit) in the number of these bacteria compared with samples in which bacteriophages had been reduced by filtration through 0.45-μm non-protein-binding membranes. Furthermore, our data indicate that the Salmonella biotypes isolated after the enrichment culture change if bacteriophages are present, thus distorting the results of the analysis.

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Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Different Enrichment Conditions Influence Bioavailability and Selection of Phenanthrene-Degrading Isolates

Applied and Environmental Microbiology ◽

10.1128/aem.66.7.2695-2702.2000 ◽

2000 ◽

Vol 66 (7) ◽

pp. 2695-2702 ◽

Cited By ~ 61

Author(s):

Robert J. Grosser ◽

Michael Friedrich ◽

David M. Ward ◽

William P. Inskeep

Keyword(s):

Organic Contaminants ◽

Contaminated Soils ◽

Solid Phase ◽

Enrichment Culture ◽

Cation Exchange Resin ◽

Culture Conditions ◽

Phenanthrene Degradation ◽

Initial Inoculum ◽

Enrichment Cultures ◽

Degradation Rates

ABSTRACT The sorption of organic contaminants by natural organic matter (NOM) often limits substrate bioavailability and is an important factor affecting microbial degradation rates in soils and sediments. We hypothesized that reduced substrate bioavailability might influence which microbial assemblages are responsible for contaminant degradation under enrichment culture conditions. Our primary goal was to characterize enrichments in which different model organic solid phases were used to establish a range of phenanthrene bioavailabilities for soil microorganisms. Phenanthrene sorption coefficients (expressed as log KD values) ranged from 3.0 liters kg−1 for Amberlite carboxylic acid cation-exchange resin (AMB) to 3.5 liters kg−1 for Biobeads polyacrylic resin (SM7) and 4.2 liters kg−1 for Biobeads divinyl benzene resin (SM2). Enrichment cultures were established for control (no sorptive phase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (from Dover, Ohio, and Libby, Mont.) as the initial inocula. The effects of sorption by model phases on the degradation of phenanthrene were evaluated for numerous transfers in order to obtain stable microbial assemblages representative of sorptive and nonsorptive enrichment cultures and to eliminate the effects of the NOM present in the initial inoculum. Phenanthrene degradation rates were similar for each soil inoculum and ranged from 4 to 5 μmol day−1 for control and sand treatments to approximately 0.4 μmol day−1 in the presence of the SM7 sorptive phase. The rates of phenanthrene degradation in the highly sorptive SM2 enrichment culture were insignificant; consequently, stable microbial populations could not be obtained. Bacterial isolates obtained from serial dilutions of enrichment culture samples exhibited significant differences in rates of phenanthrene degradation performed in the presence of SM7, suggesting that enrichments performed in the presence of a sorptive phase selected for different microbial assemblages than control treatments containing solid phase phenanthrene.

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