scholarly journals Evaluation of Toxic Effects of Aeration and Trichloroethylene Oxidation on Methanotrophic Bacteria Grown with Different Nitrogen Sources

1999 ◽  
Vol 65 (2) ◽  
pp. 766-772 ◽  
Author(s):  
Kung-Hui Chu ◽  
Lisa Alvarez-Cohen
Keyword(s):  
Respiratory Activity ◽  
Molecular Nitrogen ◽  
Nitrogen Sources ◽  
Viable Cell ◽  
Toxic Effects ◽  
Cellular Damage ◽  
Methanotrophic Bacteria ◽  
Oxidation Rates ◽  
Formate Oxidation ◽  
Soluble Methane Monooxygenase

ABSTRACT In this study we evaluated specific and nonspecific toxic effects of aeration and trichloroethylene (TCE) oxidation on methanotrophic bacteria grown with different nitrogen sources (nitrate, ammonia, and molecular nitrogen). The specific toxic effects, exerted directly on soluble methane monooxygenase (sMMO), were evaluated by comparing changes in methane uptake rates and naphthalene oxidation rates following aeration and/or TCE oxidation. Nonspecific toxic effects, defined as general cellular damage, were examined by using a combination of epifluorescent cellular stains to measure viable cell numbers based on respiratory activity and measuring formate oxidation activities following aeration and TCE transformation. Our results suggest that aeration damages predominantly sMMO rather than other general cellular components, whereas TCE oxidation exerts a broad range of toxic effects that damage both specific and nonspecific cellular functions. TCE oxidation caused sMMO-catalyzed activity and respiratory activity to decrease linearly with the amount of substrate degraded. Severe TCE oxidation toxicity resulted in total cessation of the methane, naphthalene, and formate oxidation activities and a 95% decrease in the respiratory activity of methanotrophs. The failure of cells to recover even after 7 days of incubation with methane suggests that cellular recovery following severe TCE product toxicity is not always possible. Our evidence suggests that generation of greater amounts of sMMO per cell due to nitrogen fixation may be responsible for enhanced TCE oxidation activities of nitrogen-fixing methanotrophs rather than enzymatic protection mechanisms associated with the nitrogenase enzymes.

scholarly journals Effect of Nitrogen Source on Growth and Trichloroethylene Degradation by Methane-Oxidizing Bacteria

1998 ◽  
Vol 64 (9) ◽  
pp. 3451-3457 ◽  
Author(s):  
Kung-Hui Chu ◽  
Lisa Alvarez-Cohen
Keyword(s):  
Nitrogen Source ◽  
Chemostat Culture ◽  
Molecular Nitrogen ◽  
Nitrogen Sources ◽  
Cellular Growth ◽  
Nitrogen Fixing ◽  
External Energy ◽  
Oxidation Rates ◽  
Methane Oxidizing Bacteria ◽  
Tce Degradation

ABSTRACT The effect of nitrogen source on methane-oxidizing bacteria with respect to cellular growth and trichloroethylene (TCE) degradation ability were examined. One mixed chemostat culture and two pure type II methane-oxidizing strains, Methylosinus trichosporium OB3b and strain CAC-2, which was isolated from the chemostat culture, were used in this study. All cultures were able to grow with each of three different nitrogen sources: ammonia, nitrate, and molecular nitrogen. Both M. trichosporium OB3b and strain CAC-2 showed slightly lower net cellular growth rates and cell yields but exhibited higher methane uptake rates, levels of poly-β-hydroxybutyrate (PHB) production, and naphthalene oxidation rates when grown under nitrogen-fixing conditions. The TCE-degrading ability of each culture was measured in terms of initial TCE oxidation rates and TCE transformation capacities (mass of TCE degraded/biomass inactivated), measured both with and without external energy sources. Higher initial TCE oxidation rates and TCE transformation capacities were observed in nitrogen-fixing mixed, M. trichosporium OB3b, and CAC-2 cultures than in nitrate- or ammonia-supplied cells. TCE transformation capacities were found to correlate with cellular PHB content in all three cultures. The results of this study suggest that the nitrogen-fixing capabilities of methane-oxidizing bacteria can be used to select for high-activity TCE degraders for the enhancement of bioremediation in fixed-nitrogen-limited environments.

scholarly journals Methylocella Species Are Facultatively Methanotrophic

2005 ◽  
Vol 187 (13) ◽  
pp. 4665-4670 ◽  
Author(s):  
Svetlana N. Dedysh ◽  
Claudia Knief ◽  
Peter F. Dunfield
Keyword(s):  
Methane Oxidation ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Methanotrophic Bacteria ◽  
Soluble Methane Monooxygenase ◽  
Cell Counts ◽  
Carbon Compounds ◽  
Methane Fluxes ◽  
The One ◽  
Pcr Targeting

ABSTRACT All aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carbon-carbon bonds. Here we demonstrate that members of the recently discovered genus Methylocella are an exception to this. These bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. To conclusively verify facultative growth, acetate and methane were used as model substrates in growth experiments with the type strain Methylocella silvestris BL2. Quantitative real-time PCR targeting the mmoX gene, which encodes a subunit of soluble methane monooxygenase, showed that copies of this gene increased in parallel with cell counts during growth on either acetate or methane as the sole substrate. This verified that cells possessing the genetic basis of methane oxidation grew on acetate as well as methane. Cloning of 16S rRNA genes and fluorescence in situ hybridization with strain-specific and genus-specific oligonucleotide probes detected no contaminants in cultures. The growth rate and carbon conversion efficiency were higher on acetate than on methane, and when both substrates were provided in excess, acetate was preferably used and methane oxidation was shut down. Our data demonstrate that not all methanotrophic bacteria are limited to growing on one-carbon compounds. This could have major implications for understanding the factors controlling methane fluxes in the environment.

Short term chronic toxicity of tributyltin on the testes of adult albino rats and the possible protective role of omega-3

2020 ◽  
pp. 096032712094745
Author(s):  
Marwa G Ahmed ◽  
Mona El-Demerdash Ibrahim ◽  
Hoda R El Sayed ◽  
Samah M Ahmed
Keyword(s):  
Treated Group ◽  
Toxic Effects ◽  
Cellular Damage ◽  
Antioxidant Defenses ◽  
Control Group ◽  
Albino Rats ◽  
Omega 3 ◽  
Group I

The declining rate of male fertility is a growing concern. Tributyltin (TBT) is a well-known endocrine disruptor (ED), that induces imposex in female gastropods and is widely used in various industrial applications. The aim of this study was to evaluate the toxic effects of TBT on the testes of adult albino rats and the possible role of omega-3. Forty two adult male albino rats were divided into five groups; control group (Group I) and four experimental groups: omega-3 treated group, TBT treated group, TBT & omega-3 treated group and follow up group. At the end of the study, the rats were subjected to biochemical, histological, immunohistochemical staining for Ki-67 and seminal examinations. Our results clarfied that TBT induced a significant decrease in testosterone, FSH, LH and serum glutathione peroxidase levels and a significant increase in the serum Malondialdehyde as compared to the control group. Tributyltin induced disorganization and shrinkage of seminiferous tubules, apoptosis, cellular damage and marked reduction in the germinal epithelium. A significant decrease in the cell proliferation and arrested spermatogenesis were also detected. Seminal analysis of TBT group showed a significant affection of all parameters as compared to other groups. Omega-3 ameliorated all of these hazardous effects. Follow up group still showed toxic effects. In conclusion, TBT has a toxic effect on the testis. Increased testicular oxidative stress, cellular damage and arrest of spermatogenesis with attenuation in antioxidant defenses are all contributing factors. Omega-3 can protect against TBT induced reproductive toxicity.

scholarly journals Gaseous VOCs rapidly modify particulate matter and its biological effects – Part 1: Simple VOCs and model PM

2012 ◽  
Vol 12 (2) ◽  
pp. 5065-5105 ◽  
Author(s):  
S. Ebersviller ◽  
K . Lichtveld ◽  
K. G. Sexton ◽  
J. Zavala ◽  
Y-H. Lin ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Gas Phase ◽  
Biological Effects ◽  
Toxic Effects ◽  
Cellular Damage ◽  
Lung Cells ◽  
Subsequent Work ◽  
Human Lung Cells ◽  
Air Stream ◽  
Organic Gases

Abstract. This is the first of a three-part study designed to demonstrate dynamic entanglements among gaseous organic compounds (VOC), particulate matter (PM), and their subsequent potential biological effects. We study these entanglements in increasingly complex VOC and PM mixtures in urban-like conditions in a large outdoor chamber. To the traditional chemical and physical characterizations of gas and PM, we added new measurements of gas-only- and PM-only-biological effects, using cultured human lung cells as model indicators. These biological effects are assessed here as increases in cellular damage or expressed irritation (i.e., cellular toxic effects) from cells exposed to chamber air relative to cells exposed to clean air. The exposure systems permit gas-only- or PM-only-exposures from the same air stream containing both gases and PM in equilibria, i.e., there are no extractive operations prior to cell exposure. Our simple experiments in this part of the study were designed to eliminate many competing atmospheric processes to reduce ambiguity in our results. Simple volatile and semi-volatile organic gases that have inherent cellular toxic properties were tested individually for biological effect in the dark (at constant humidity). Airborne mixtures were then created with each compound and PM that has no inherent cellular toxic properties for another cellular exposure. Acrolein and p-tolualdehyde were used as model VOCs and mineral oil aerosol (MOA) was selected as a surrogate for organic-containing PM. MOA is appropriately complex in composition to represent ambient PM, and it exhibits no inherent cellular toxic effects and thus did not contribute any biological detrimental effects on its own. Chemical measurements, combined with the responses of our biological exposures, clearly demonstrate that gas-phase pollutants can modify the composition of PM (and its resulting detrimental effects on lung cells) – even if the gas-phase pollutants are not considered likely to partition to the condensed phase: the VOC-modified-PM showed significantly more damage and inflammation to lung cells than did the original PM. Because gases and PM are transported and deposited differently within the atmosphere and the lungs, these results have significant consequences. For example, current US policies for research and regulation of PM do not recognize this "effect modification" phenomena (NAS, 2004). These results present an unambiguous demonstration that – even in these simple mixtures – physical and thermal interactions alone can cause a modification of the distribution of species among the phases of airborne pollution mixtures and can result in a non-toxic phase becoming toxic due to atmospheric thermal processes only. Subsequent work extends the simple results reported here to systems with photochemical transformations of complex urban mixtures and to systems with diesel exhaust produced by different fuels.

scholarly journals Gaseous VOCs rapidly modify particulate matter and its biological effects – Part 1: Simple VOCs and model PM

2012 ◽  
Vol 12 (24) ◽  
pp. 12277-12292 ◽  
Author(s):  
S. Ebersviller ◽  
K. Lichtveld ◽  
K. G. Sexton ◽  
J. Zavala ◽  
Y.-H. Lin ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Gas Phase ◽  
Biological Effects ◽  
Toxic Effects ◽  
Cellular Damage ◽  
Lung Cells ◽  
Subsequent Work ◽  
Human Lung Cells ◽  
Air Stream ◽  
Wide Range

Abstract. This is the first of a three-part study designed to demonstrate dynamic entanglements among gaseous organic compounds (VOC), particulate matter (PM), and their subsequent potential biological effects. We study these entanglements in increasingly complex VOC and PM mixtures in urban-like conditions in a large outdoor chamber. To the traditional chemical and physical characterizations of gas and PM, we added new measurements of biological effects, using cultured human lung cells as model indicators. These biological effects are assessed here as increases in cellular damage or expressed irritation (i.e., cellular toxic effects) from cells exposed to chamber air relative to cells exposed to clean air. The exposure systems permit virtually gas-only- or PM-only-exposures from the same air stream containing both gases and PM in equilibria, i.e., there are no extractive operations prior to cell exposure. Our simple experiments in this part of the study were designed to eliminate many competing atmospheric processes to reduce ambiguity in our results. Simple volatile and semi-volatile organic gases that have inherent cellular toxic properties were tested individually for biological effect in the dark (at constant humidity). Airborne mixtures were then created with each compound to which we added PM that has no inherent cellular toxic properties for another cellular exposure. Acrolein and p-tolualdehyde were used as model VOCs and mineral oil aerosol (MOA) was selected as a surrogate for organic-containing PM. MOA is appropriately complex in composition to represent ambient PM, and exhibits no inherent cellular toxic effects and thus did not contribute any biological detrimental effects on its own. Chemical measurements, combined with the responses of our biological exposures, clearly demonstrate that gas-phase pollutants can modify the composition of PM (and its resulting detrimental effects on lung cells). We observed that, even if the gas-phase pollutants are not considered likely to partition to the condensed phase, the VOC-modified-PM showed significantly more damage and inflammation to lung cells than did the original PM. Because gases and PM are transported and deposited differently within the atmosphere and the lungs, these results have significant consequences for a wide range of people. For example, current US policies for research and regulation of PM do not recognize this "effect modification" phenomena (NAS, 2004). These results present an unambiguous demonstration that – even in these simple mixtures – physical and thermal interactions alone can cause a modification of the distribution of species among the phases of airborne pollution mixtures that can result in a non-toxic phase becoming toxic due to atmospheric thermal processes only. Subsequent work (described in companion papers) extends the simple results reported here to systems with photochemical transformations of complex urban mixtures and to systems with diesel exhaust produced by different fuels.

Nitrogen Fixation and the Utilization of Other Inorganic Nitrogen Sources in a Subarctic Lake

1968 ◽  
Vol 25 (10) ◽  
pp. 2101-2110 ◽  
Author(s):  
Vera A. Billaud
Keyword(s):  
Nitrogen Source ◽  
Nitrate Uptake ◽  
Inorganic Nitrogen ◽  
Molecular Nitrogen ◽  
Nitrogen Sources ◽  
Lake Surface ◽  
Interior Alaska ◽  
Uptake Rates ◽  
Tracer Methods ◽  
Subarctic Lake

A year-round limnological study of the biological utilization of molecular nitrogen, ammonia, and nitrate in Smith Lake, a small subarctic lake in interior Alaska, showed that ammonia was consistently the most important nitrogen source. Of the two main algal production periods, the first took place under the ice in May, and depended on ammonia accumulated during the winter for a nitrogen source. The population at this time consisted largely of microflagellates. Chlamydomonas, Euglena, Chlorella, and Mellamonas were among the identified algae present. Immediately after the ice melted from the lake surface, a second population developed. These algae, consisting almost exclusively of Anabaena flos-aquae, used ammonia, nitrate, and molecular nitrogen simultaneously. During the remainder of the summer, uptake rates remained relatively low, with ammonia the most important nitrogen source; during the fall, nitrate uptake briefly approached the magnitude of ammonia uptake. 15N tracer methods were used to measure the uptake rates in this work.

scholarly journals Niche separation within aerobic methanotrophic bacteria across lakes and its link to methane oxidation rates

2019 ◽  
Vol 22 (2) ◽  
pp. 738-751
Author(s):  
Paula C. J. Reis ◽  
Shoji D. Thottathil ◽  
Clara Ruiz‐González ◽  
Yves T. Prairie
Keyword(s):  
Methane Oxidation ◽  
Niche Separation ◽  
Methanotrophic Bacteria ◽  
Oxidation Rates

scholarly journals Stable Isotope Probing Analysis of the Diversity and Activity of Methanotrophic Bacteria in Soils from the Canadian High Arctic

2010 ◽  
Vol 76 (17) ◽  
pp. 5773-5784 ◽  
Author(s):  
Christine Martineau ◽  
Lyle G. Whyte ◽  
Charles W. Greer
Keyword(s):  
Stable Isotope ◽  
16S Rrna ◽  
High Arctic ◽  
Stable Isotope Probing ◽  
Type I ◽  
Methanotrophic Bacteria ◽  
Gene Sequences ◽  
Canadian High Arctic ◽  
Oxidation Rates ◽  
Arctic Soils

ABSTRACT The melting of permafrost and its potential impact on CH4 emissions are major concerns in the context of global warming. Methanotrophic bacteria have the capacity to mitigate CH4 emissions from melting permafrost. Here, we used quantitative PCR (qPCR), stable isotope probing (SIP) of DNA, denaturing gradient gel electrophoresis (DGGE) fingerprinting, and sequencing of the 16S rRNA and pmoA genes to study the activity and diversity of methanotrophic bacteria in active-layer soils from Ellesmere Island in the Canadian high Arctic. Results showed that most of the soils had the capacity to oxidize CH4 at 4°C and at room temperature (RT), but the oxidation rates were greater at RT than at 4°C and were significantly enhanced by nutrient amendment. The DGGE banding patterns associated with active methanotrophic bacterial populations were also different depending on the temperature of incubation and the addition of nutrients. Sequencing of the 16S rRNA and pmoA genes indicated a low diversity of the active methanotrophic bacteria, with all methanotroph 16S rRNA and pmoA gene sequences being related to type I methanotrophs from Methylobacter and Methylosarcina. The dominance of type I methanotrophs over type II methanotrophs in the native soil samples was confirmed by qPCR of the 16S rRNA gene with primers specific for these two groups of bacteria. The 16S rRNA and pmoA gene sequences related to those of Methylobacter tundripaludum were found in all soils, regardless of the incubation conditions, and they might therefore play a role in CH4 degradation in situ. This work is providing new information supporting the potential importance of Methylobacter spp. in Arctic soils found in previous studies and contributes to the limited body of knowledge on methanotrophic activity and diversity in this extreme environment.

scholarly journals Nitrogen Metabolism of an Anoxygenic Filamentous Phototrophic Bacterium Oscillocholris trichoides Strain DG-6

Microbiology ◽  
2021 ◽  
Vol 90 (4) ◽  
pp. 428-434
Author(s):  
R. N. Ivanovsky ◽  
N. V. Lebedeva ◽  
O. I. Keppen ◽  
T. P. Tourova
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Source ◽  
Glutamate Dehydrogenase ◽  
Molecular Nitrogen ◽  
Single Gene ◽  
Nitrogen Sources ◽  
Entire Family ◽  
Ammonium N ◽  
Expression Product ◽  
Typical Strain

Abstract— The possible nitrogen sources for Osc. trichoides DG6, a typical strain of the Oscillochloridaceae family, are ammonium, N2, glutamate, asparagine, glycine, and glutamine. The assimilation of molecular nitrogen occurs with the participation of nitrogenase, the structural gene of which, nifH, is located in the gene cluster which also includes the genes of the nifD and nifK nitrogenase subunits and the auxiliary nifB gene. Considering that nifHBDK clusters have been also annotated in the genomes of other members of the Oscillochloridaceae family, including uncultured and candidate taxa, it can be assumed that the ability to fix nitrogen is a property immanent for this entire family. The pathways for assimilating ammonium in the cells grown using different nitrogen sources may differ. Osc. trichoides DG6 growing in a medium containing ammonium assimilated it with the participation of glutamate dehydrogenase, which is determined by a single gene. The expression product of this gene has dual functionality and can be used to implement the reaction with both NAD and NADP. With the growth of Osc. trichoides DG6 on a medium with glutamate as the only nitrogen source all the enzymes necessary for the implementation of the GS‑GOGAT pathway were found in the cells. However, for the glutamine synthetase reaction, ammonium, which was absent in the growth medium, was required. The source of ammonium may be glutamate metabolized through glutamate dehydrogenase.

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