@article {1561, title = {4-methylphenol produced in freshwater sediment microcosms is not a bisphenol A metabolite.}, journal = {Chemosphere}, volume = {117}, year = {2014}, month = {2014 Dec}, pages = {521-6}, abstract = {

4-Methylphenol (4-MP), a putative bisphenol A (BPA) degradation intermediate, was detected at concentrations reaching 2.1 mg L(-1) in anoxic microcosms containing 10 mg L(-1) BPA and 5 g of freshwater sediment material collected from four geographically distinct locations and amended with nitrate, nitrite, ferric iron, or bicarbonate as electron acceptors. 4-MP accumulation was transient, and 4-MP degradation was observed under all redox conditions tested. 4-MP was not detected in microcosms not amended with BPA. Unexpectedly, incubations with (13)C-labeled BPA failed to produce (13)C-labeled 4-MP suggesting that 4-MP was not derived from BPA. The detection of 4-MP in live microcosms amended with lactate, but not containing BPA corroborated that BPA was not the source of 4-MP. These findings demonstrate that the transient formation of 4-MP as a possible BPA degradation intermediate must be interpreted cautiously, as microbial activity in streambed microcosms may generate 4-MP from sediment-associated organic material.

}, keywords = {Anaerobiosis, Benzhydryl Compounds, Biodegradation, Environmental, Chromatography, High Pressure Liquid, Cresols, Environmental Monitoring, Fresh Water, Gas Chromatography-Mass Spectrometry, Geologic Sediments, Phenols, Water Pollutants, Chemical}, issn = {1879-1298}, doi = {10.1016/j.chemosphere.2014.09.008}, author = {Im, Jeongdae and Prevatte, Carson W and Lee, Hong Geun and Campagna, Shawn R and L{\"o}ffler, Frank E} } @article {1564, title = {A field trial of nutrient stimulation of methanotrophs to reduce greenhouse gas emissions from landfill cover soils.}, journal = {J Air Waste Manag Assoc}, volume = {63}, year = {2013}, month = {2013 Mar}, pages = {300-9}, abstract = {

UNLABELLED: Landfills are among the major sources of anthropogenic methane (CH4) estimated to reach 40 x 10(9) kg per year worldwide by 2015 (IPCC, 2007). A 2 1/2-year field experiment was conducted at a closed landfill in western Michigan where methanotrophs, methane-consuming bacteria, were stimulated by nutrient addition to the soil without significantly increasing biogenic nitrous oxide (N2O) production. The effects of the nitrogen amendments (KNO3 and NH4Cl), phenylacetylene (a selective inhibitor of nitrifying bacteria that contribute to N2O production), and a canopy (to reduce direct water infiltration) on the vertical soil gas profiles of CH4, CO2, and O2 were measured in the top meter of the soil. Methane and nitrous oxide fluxes were calculated from the corresponding soil gas concentration gradients with respect to depth and a Millington-Quirk diffusivity coefficient in soil derived empirically from soil porosity, water content, and diffusivity coefficients in air from the literature. Methane flux estimates were as high as 218.4 g m(-2) day(-1) in the fall and 12.8 g/m(-2) day(-1) in the summer. During the spring and summer CH4 fluxes were reduced by more than half by adding KNO3 and NH4Cl into the soil as compared to control plots, while N2O fluxes increased substantially. The concurrent addition of phenylacetylene to the amendment decreased peak N2O production by half and the rate of peak methane oxidation by about one-third. The seasonal average methane and N2O flux data were extrapolated to estimate the reduction of CH4 and N2O fluxes into the atmosphere by nitrogen and inhibitor addition to the cover soils. The results suggest that such additions coupled with soil moisture management may provide a potential strategy to significantly reduce greenhouse gas emissions from landfills.

IMPLICATIONS: The results of a 2 1/2-year study of effects of nutrient stimulation on methane oxidation in landfill cover soils demonstrates that nutrient addition does decrease methane emissions. The work further underscores the control which soil moisture exerts on methane oxidation. Water management is critical to the success of methane oxidation strategies.

}, keywords = {Biodegradation, Environmental, Gases, Greenhouse Effect, Methane, Oxidation-Reduction, Soil, Soil Microbiology, Waste Management}, issn = {1096-2247}, author = {Lizik, William and Im, Jeongdae and Semrau, Jeremy D and Barcelona, Michael J} } @article {1565, title = {Guided cobalamin biosynthesis supports Dehalococcoides mccartyi reductive dechlorination activity.}, journal = {Philos Trans R Soc Lond B Biol Sci}, volume = {368}, year = {2013}, month = {2013 Apr 19}, pages = {20120320}, abstract = {

Dehalococcoides mccartyi strains are corrinoid-auxotrophic Bacteria and axenic cultures that require vitamin B12 (CN-Cbl) to conserve energy via organohalide respiration. Cultures of D. mccartyi strains BAV1, GT and FL2 grown with limiting amounts of 1 {\textmu}g l(-1) CN-Cbl quickly depleted CN-Cbl, and reductive dechlorination of polychlorinated ethenes was incomplete leading to vinyl chloride (VC) accumulation. In contrast, the same cultures amended with 25 {\textmu}g l(-1) CN-Cbl exhibited up to 2.3-fold higher dechlorination rates, 2.8-9.1-fold increased growth yields, and completely consumed growth-supporting chlorinated ethenes. To explore whether known cobamide-producing microbes supply Dehalococcoides with the required corrinoid cofactor, co-culture experiments were performed with the methanogen Methanosarcina barkeri strain Fusaro and two acetogens, Sporomusa ovata and Sporomusa sp. strain KB-1, as Dehalococcoides partner populations. During growth with H2/CO2, M. barkeri axenic cultures produced 4.2 {\textpm} 0.1 {\textmu}g l(-1) extracellular cobamide (factor III), whereas the Sporomusa cultures produced phenolyl- and p-cresolyl-cobamides. Neither factor III nor the phenolic cobamides supported Dehalococcoides reductive dechlorination activity suggesting that M. barkeri and the Sporomusa sp. cannot fulfil Dehalococcoides{\textquoteright} nutritional requirements. Dehalococcoides dechlorination activity and growth occurred in M. barkeri and Sporomusa sp. co-cultures amended with 10 {\textmu}M 5{\textquoteright},6{\textquoteright}-dimethylbenzimidazole (DMB), indicating that a cobalamin is a preferred corrinoid cofactor of strains BAV1, GT and FL2 when grown with chlorinated ethenes as electron acceptors. Even though the methanogen and acetogen populations tested did not produce cobalamin, the addition of DMB enabled guided biosynthesis and generated a cobalamin that supported Dehalococcoides{\textquoteright} activity and growth. Guided cobalamin biosynthesis may offer opportunities to sustain and enhance Dehalococcoides activity in contaminated subsurface environments.

}, keywords = {Bacteriological Techniques, Benzimidazoles, Biodegradation, Environmental, Chloroflexi, Chromatography, High Pressure Liquid, Coculture Techniques, Culture Media, Dichloroethylenes, Halogenation, Oxidation-Reduction, Trichloroethylene, Vitamin B 12}, issn = {1471-2970}, doi = {10.1098/rstb.2012.0320}, author = {Yan, Jun and Im, Jeongdae and Yang, Yi and L{\"o}ffler, Frank E} } @article {1568, title = {Pollutant degradation by a Methylocystis strain SB2 grown on ethanol: bioremediation via facultative methanotrophy.}, journal = {FEMS Microbiol Lett}, volume = {318}, year = {2011}, month = {2011 May}, pages = {137-42}, abstract = {

A facultative methanotroph, Methylocystis strain SB2, was examined for its ability to degrade chlorinated hydrocarbons when grown on methane or ethanol. Strain SB2 grown on methane degraded vinyl chloride (VC), trans-dichloroethylene (t-DCE), trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), and chloroform (CF), but not dichloromethane (DCM). Growth on methane was reduced in the presence of any chlorinated hydrocarbon. Strain SB2 grown on ethanol degraded VC, t-DCE, and TCE, and 1,1,1-TCA, but not DCM or CF. With the exception of 1,1,1-TCA, the growth of strain SB2 on ethanol was not affected by any individual chlorinated hydrocarbon. No degradation of any chlorinated hydrocarbon was observed when acetylene was added to ethanol-grown cultures, indicating that this degradation was due to particulate methane monooxygenase (pMMO) activity. When mixtures of chlorinated alkanes or alkenes were added to cultures growing on methane or ethanol, chlorinated alkene degradation occurred, but chlorinated alkanes were not, and growth was reduced on both methane and ethanol. Collectively, these data indicate that competitive inhibition of pMMO activity limits methanotrophic growth and pollutant degradation. Facultative methanotrophy may thus be useful to extend the utility of methanotrophs for bioremediation as the use of alternative growth substrates allows for pMMO activity to be focused on pollutant degradation.

}, keywords = {Autotrophic Processes, Biodegradation, Environmental, Environmental Pollutants, Ethanol, Hydrocarbons, Chlorinated, Methane, Methylocystaceae}, issn = {1574-6968}, doi = {10.1111/j.1574-6968.2011.02249.x}, author = {Im, Jeongdae and Semrau, Jeremy D} }