scholarly journals Distribution, Activities, and Interactions of Methanogens and Sulfate-Reducing Prokaryotes in the Florida Everglades

2015 ◽  
Vol 81 (21) ◽  
pp. 7431-7442 ◽  
Author(s):  
Hee-Sung Bae ◽  
M. Elizabeth Holmes ◽  
Jeffrey P. Chanton ◽  
K. Ramesh Reddy ◽  
Andrew Ogram
Keyword(s):  
Water Conservation ◽  
Specific Inhibitor ◽  
Florida Everglades ◽  
Conservation Areas ◽  
Content Type ◽  
Functional Activities ◽  
Sulfate Reducing ◽  
Nutrient Gradient ◽  
Reductase Gene ◽  
High Concentrations

ABSTRACTTo gain insight into the mechanisms controlling methanogenic pathways in the Florida Everglades, the distribution and functional activities of methanogens and sulfate-reducing prokaryotes (SRPs) were investigated in soils (0 to 2 or 0 to 4 cm depth) across the well-documented nutrient gradient in the water conservation areas (WCAs) caused by runoff from the adjacent Everglades Agricultural Area. The methyl coenzyme M reductase gene (mcrA) sequences that were retrieved from WCA-2A, an area with relatively high concentrations of SO42−(≥39 μM), indicated that methanogens inhabiting this area were broadly distributed within the ordersMethanomicrobiales,Methanosarcinales,Methanocellales,Methanobacteriales, andMethanomassiliicoccales. In more than 3 years of monitoring, quantitative PCR (qPCR) using newly designed group-specific primers revealed that the hydrogenotrophicMethanomicrobialeswere more numerous than theMethanosaetaceaeobligatory acetotrophs in SO42−-rich areas of WCA-2A, while theMethanosaetaceaewere dominant over theMethanomicrobialesin WCA-3A (with relatively low SO42−concentrations; ≤4 μM). qPCR ofdsrBsequences also indicated that SRPs are present at greater numbers than methanogens in the WCAs. In an incubation study with WCA-2A soils, addition of MoO42−(a specific inhibitor of SRP activity) resulted in increased methane production rates, lower apparent fractionation factors [αapp; defined as (amount of δ13CO2+ 1,000)/(amount of δ13CH4+ 1,000)], and higherMethanosaetaceaemcrAtranscript levels compared to those for the controls without MoO42−. These results indicate that SRPs play crucial roles in controlling methanogenic pathways and in shaping the structures of methanogen assemblages as a function of position along the nutrient gradient.

scholarly journals Syntrophs Dominate Sequences Associated with the Mercury Methylation-Related GenehgcAin the Water Conservation Areas of the Florida Everglades

2014 ◽  
Vol 80 (20) ◽  
pp. 6517-6526 ◽  
Author(s):  
Hee-Sung Bae ◽  
Forrest E. Dierberg ◽  
Andrew Ogram
Keyword(s):  
Water Conservation ◽  
Florida Everglades ◽  
Nutrient Concentrations ◽  
Mercury Methylation ◽  
Conservation Areas ◽  
Wildlife Health ◽  
Gene Encoding ◽  
Content Type ◽  
Sulfate Reducing ◽  
Aquatic Food

ABSTRACTThe mechanisms and rates of mercury methylation in the Florida Everglades are of great concern because of potential adverse impacts on human and wildlife health through mercury accumulation in aquatic food webs. We developed a new PCR primer set targetinghgcA, a gene encoding a corrinoid protein essential for Hg methylation across broad phylogenetic boundaries, and used this primer set to study the distribution ofhgcAsequences in soils collected from three sites along a gradient in sulfate and nutrient concentrations in the northern Everglades. The sequences obtained were distributed in diverse phyla, includingProteobacteria,Chloroflexi,Firmicutes, andMethanomicrobia; however,hgcAclone libraries from all sites were dominated by sequences clustering within the orderSyntrophobacteralesof theDeltaproteobacteria(49 to 65% of total sequences).dsrBmRNA sequences, representing active sulfate-reducing prokaryotes at the time of sampling, obtained from these sites were also dominated bySyntrophobacterales(75 to 89%). Laboratory incubations with soils taken from the site low in sulfate concentrations also suggested that Hg methylation activities were primarily mediated by members of the orderSyntrophobacterales, with some contribution by methanogens,Chloroflexi, iron-reducingGeobacter, and non-sulfate-reducingFirmicutesinhabiting the sites. This suggests that prokaryotes distributed within clades defined by syntrophs are the predominant group controlling methylation of Hg in low-sulfate areas of the Everglades. Any strategy for managing mercury methylation in the Everglades should consider that net mercury methylation is not limited to the action of sulfate reduction.

scholarly journals Methanogens Are Major Contributors to Nitrogen Fixation in Soils of the Florida Everglades

2018 ◽  
Vol 84 (7) ◽  
Author(s):  
Hee-Sung Bae ◽  
Elise Morrison ◽  
Jeffrey P. Chanton ◽  
Andrew Ogram
Keyword(s):  
Primary Productivity ◽  
Methane Production ◽  
Water Conservation ◽  
Significant Proportion ◽  
Florida Everglades ◽  
Freshwater Wetland ◽  
Rrna Genes ◽  
Content Type ◽  
N Cycle ◽  
N Limitation

ABSTRACTThe objective of this study was to investigate the interaction of the nitrogen (N) cycle with methane production in the Florida Everglades, a large freshwater wetland. This study provides an initial analysis of the distribution and expression of N-cycling genes in Water Conservation Area 2A (WCA-2A), a section of the marsh that underwent phosphorus (P) loading for many years due to runoff from upstream agricultural activities. The elevated P resulted in increased primary productivity and an N limitation in P-enriched areas. Results from quantitative real-time PCR (qPCR) analyses indicated that the N cycle in WCA-2A was dominated bynifHandnirK/S, with an increasing trend in copy numbers in P-impacted sites. ManynifHsequences (6 to 44% of the total) andnifHtranscript sequences (2 to 49%) clustered with the methanogenicEuryarchaeota, in stark contrast to the proportion of core gene sequences representingArchaea(≤0.27% of SSU rRNA genes) for the WCA-2A microbiota. Notably, archaealnifHgene transcripts were detected at all sites and comprised a significant proportion of totalnifHtranscripts obtained from the unimpacted site, indicating that methanogens are actively fixing N2. Laboratory incubations with soils taken from WCA-2A producednifHtranscripts with the production of methane from H2plus CO2and acetate as electron donors and carbon sources. Methanogenic N2fixation is likely to be an important, although largely unrecognized, route through which fixed nitrogen enters the anoxic soils of the Everglades and may have significant relevance regarding methane production in wetlands.IMPORTANCEWetlands are the most important natural sources of the greenhouse gas methane, and much of that methane emanates from (sub)tropical peatlands. Primary productivity in these peatlands is frequently limited by the availability of nitrogen or phosphorus; however, the response to nutrient limitations of microbial communities that control biogeochemical cycling critical to ecosystem function may be complex and may be associated with a range of processes, including methane production. We show that many, if not most, of the methanogens in the peatlands of the Florida Everglades possess thenifHgene and actively express it for N2fixation coupled with methanogenesis. These findings indicate that archaeal N2fixation would play crucial role in methane emissions and overall N cycle in subtropical wetlands suffering N limitation.

Biological Mechanisms of H2S Formation in Sewer Pipes

1992 ◽  
Vol 26 (3-4) ◽  
pp. 907-914 ◽  
Author(s):  
A. Attal ◽  
M. Brigodiot ◽  
P. Camacho ◽  
J. Manem
Keyword(s):  
Suspended Solid ◽  
Urban Wastewater ◽  
Biological Mechanisms ◽  
Sewer Pipes ◽  
Sulfate Reducing ◽  
Biological Phenomena ◽  
Low Concentrations ◽  
Production Of Hydrogen ◽  
High Concentrations ◽  
Reducing Bacteria

The purpose of this study is to gain a better understanding of the biological phenomena involved in the production of hydrogen sulfide in urban wastewater (UWW) systems. It is found that the UWW itself naturally possesses the biomass needed to consume the sulfates. These heterotrophic sulfate-reducing bacteria populations, though immediately active in strict anaerobic conditions, are present only in very low concentrations in the UWW. A concentration of them was studied within the pressure pipes, in the form of deposits, and this justifies the high concentrations of sulfides measured in certain wastewater networks. There are two reasons why the ferrous sulfate used as a treatment in any wastewater networks should not cause the production of additional sulfides. Firstly, the sulfate consumption kinetics are always too slow, relative to the residence time of the water in the pipe, for all of the sulfates to be consumed anyway. Secondly, the amount of assimilable carbon, soluble carbon, and carbon from suspended solid (SS) hydrolysis is insufficient.

Prostacyclin and cerebral vessel relaxation

1982 ◽  
Vol 57 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Kamal S. Paul ◽  
Eric T. Whalley ◽  
Christine Forster ◽  
Richard Lye ◽  
John Dutton
Keyword(s):  
Angiotensin Ii ◽  
Arterial Spasm ◽  
Cerebral Vessel ◽  
Content Type ◽  
Wide Range ◽  
Potent Vasodilator ◽  
Dose Dependent Fashion ◽  
Basilar Arteries ◽  
High Concentrations

✓ The authors have studied the ability of prostacyclin to reverse contractions of human basilar arteries in vitro that were induced by a wide range of substances implicated in the etiology of cerebral arterial spasm. Prostacyclin (10−10 to 10−6M) caused a dose-related reversal of contractions induced by 5-hydroxytryptamine, noradrenaline, angiotensin II, prostaglandin (PG)F2α, and U-46619 (a thromboxane-A2 mimetic). These agents were tested at concentrations or volumes that produced almost maximum or maximum responses and those that produced approximately 50% of the maximum response. Contractions induced by maximum concentrations of angiotensin II and U-46619 were least affected by prostacyclin. In addition, contractions induced by thromboxane-A2 generated from guinea-pig lung were reversed in a dose-dependent fashion by prostacyclin. This ability of prostacyclin to physiologically antagonize contractions of the human basilar artery in vitro induced by high concentrations of various spasmogenic agents suggests that such a potent vasodilator agent or more stable analogue may be of value in the treatment of such disorders as cerebral arterial spasm following subarachnoid hemorrhage.

scholarly journals Antibiotic Resistance Markers in Burkholderia pseudomallei Strain Bp1651 Identified by Genome Sequence Analysis

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Julia V. Bugrysheva ◽  
David Sue ◽  
Jay E. Gee ◽  
Mindy G. Elrod ◽  
Alex R. Hoffmaster ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Clavulanic Acid ◽  
Burkholderia Pseudomallei ◽  
Efflux Pump ◽  
Point Mutations ◽  
Comparative Genomic ◽  
Content Type ◽  
Reductase Gene ◽  
Amoxicillin Clavulanic Acid ◽  
Imipenem Resistance

ABSTRACT Burkholderia pseudomallei Bp1651 is resistant to several classes of antibiotics that are usually effective for treatment of melioidosis, including tetracyclines, sulfonamides, and β-lactams such as penicillins (amoxicillin-clavulanic acid), cephalosporins (ceftazidime), and carbapenems (imipenem and meropenem). We sequenced, assembled, and annotated the Bp1651 genome and analyzed the sequence using comparative genomic analyses with susceptible strains, keyword searches of the annotation, publicly available antimicrobial resistance prediction tools, and published reports. More than 100 genes in the Bp1651 sequence were identified as potentially contributing to antimicrobial resistance. Most notably, we identified three previously uncharacterized point mutations in penA, which codes for a class A β-lactamase and was previously implicated in resistance to β-lactam antibiotics. The mutations result in amino acid changes T147A, D240G, and V261I. When individually introduced into select agent-excluded B. pseudomallei strain Bp82, D240G was found to contribute to ceftazidime resistance and T147A contributed to amoxicillin-clavulanic acid and imipenem resistance. This study provides the first evidence that mutations in penA may alter susceptibility to carbapenems in B. pseudomallei. Another mutation of interest was a point mutation affecting the dihydrofolate reductase gene folA, which likely explains the trimethoprim resistance of this strain. Bp1651 was susceptible to aminoglycosides likely because of a frameshift in the amrB gene, the transporter subunit of the AmrAB-OprA efflux pump. These findings expand the role of penA to include resistance to carbapenems and may assist in the development of molecular diagnostics that predict antimicrobial resistance and provide guidance for treatment of melioidosis.

scholarly journals Regulatory Effect of SlyA onrcsBExpression inSalmonella entericaSerovar Typhimurium

2018 ◽  
Vol 201 (4) ◽  
Author(s):  
María F. Ballesteros ◽  
Mónica F. Torrez Lamberti ◽  
Juan V. Farizano ◽  
María M. Pescaretti ◽  
Mónica A. Delgado
Keyword(s):  
Virulence Gene ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Low Concentrations ◽  
Antagonistic Behavior ◽  
Serovar Typhimurium ◽  
Direct Binding ◽  
High Concentrations ◽  
Encoding Genes ◽  
Different Levels

ABSTRACTTheSalmonella entericaserovar Typhimurium RcsCDB system regulates the synthesis of colanic acid and the flagellum as well as the expression of virulence genes. We previously demonstrated that thercsC11mutant, which constitutively activates the RcsB regulator, attenuatesSalmonellavirulence in an animal model. This attenuated phenotype was also produced by deletion of theslyAgene. In this work, we investigated if this antagonistic behavior is produced by modulating the expression of both regulator-encoding genes. We demonstrated that SlyA overproduction negatively regulatesrcsBtranscription. A bioinformatics analysis enabled us to identify putative SlyA binding sites on both promoters, PrcsDBand PrcsB, which controlrcsBtranscriptional levels. We also determined that SlyA is able to recognize and bind to these predicted sites to modulate the activity of bothrcsBpromoters. According to these results, SlyA repressesrcsBtranscription by direct binding to specific sites located on thercsBpromoters, thus accounting for the attenuated/virulence antagonistic behaviors. Moreover, we showed that the opposite effect between both regulators also physiologically affects theSalmonellamotility phenotype. In this sense, we observed that under SlyA overproduction, PrcsBis repressed, and consequently, bacterial motility is increased. On the basis of these results, we suggest that during infection, the different RcsB levels produced act as a switch between the virulent and attenuated forms ofSalmonella. Thereby, we propose that higher concentrations of RcsB tilt the balance toward the attenuated form, while absence or low concentrations resulting from SlyA overproduction tilt the balance toward the virulent form.IMPORTANCEThe antagonistic behavior of RcsB and SlyA on virulence gene expression led us to hypothesize that there is interplay between both regulators in a regulatory network and these could be considered coordinators of this process. Here, we report that the SlyA virulence factor influences motility behavior by controllingrcsBtranscription from the PrcsBpromoter. We also demonstrate that SlyA negatively affects the expression of thercsBgene by direct binding to PrcsDBand PrcsBpromoters. We suggest that different levels of RcsB act as a switch between the virulent and attenuated forms ofSalmonella, where high concentrations of the regulator tend to tilt the balance toward the attenuated form and low concentrations or its absence tilt it toward the virulent form.

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