scholarly journals Bacterial virulence against an oceanic bloom-forming phytoplankter is mediated by algal DMSP

2018 ◽  
Vol 4 (10) ◽  
pp. eaau5716 ◽  
Author(s):  
Noa Barak-Gavish ◽  
Miguel José Frada ◽  
Chuan Ku ◽  
Peter A. Lee ◽  
Giacomo R. DiTullio ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Bacterial Pathogen ◽  
Sulfur Cycle ◽  
Bacterial Virulence ◽  
Algicidal Bacteria ◽  
Specific Response ◽  
Algal Strain ◽  
Alternative Product ◽  
Unique Strain ◽  
Algicidal Effects

Emiliania huxleyiis a bloom-forming microalga that affects the global sulfur cycle by producing large amounts of dimethylsulfoniopropionate (DMSP) and its volatile metabolic product dimethyl sulfide. Top-down regulation ofE. huxleyiblooms has been attributed to viruses and grazers; however, the possible involvement of algicidal bacteria in bloom demise has remained elusive. We demonstrate that aRoseobacterstrain,SulfitobacterD7, that we isolated from a North AtlanticE. huxleyibloom, exhibited algicidal effects againstE. huxleyiupon coculturing. Both the alga and the bacterium were found to co-occur during a naturalE. huxleyibloom, therefore establishing this host-pathogen system as an attractive, ecologically relevant model for studying algal-bacterial interactions in the oceans. During interaction,SulfitobacterD7 consumed and metabolized algal DMSP to produce high amounts of methanethiol, an alternative product of DMSP catabolism. We revealed a unique strain-specific response, in whichE. huxleyistrains that exuded higher amounts of DMSP were more susceptible toSulfitobacterD7 infection. Intriguingly, exogenous application of DMSP enhanced bacterial virulence and induced susceptibility in an algal strain typically resistant to the bacterial pathogen. This enhanced virulence was highly specific to DMSP compared to addition of propionate and glycerol which had no effect on bacterial virulence. We propose a novel function for DMSP, in addition to its central role in mutualistic interactions among marine organisms, as a mediator of bacterial virulence that may regulateE. huxleyiblooms.

scholarly journals Bacterial virulence against an oceanic bloom-forming phytoplankter is mediated by algal DMSP

2018 ◽  
Author(s):  
Noa Barak-Gavish ◽  
Miguel José Frada ◽  
Peter A. Lee ◽  
Giacomo R. DiTullio ◽  
Chuan Ku ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Bacterial Pathogen ◽  
Sulfur Cycle ◽  
Bacterial Virulence ◽  
Algicidal Bacteria ◽  
Specific Response ◽  
Algal Strain ◽  
Alternative Product ◽  
Unique Strain ◽  
Algicidal Effects

AbstractEmiliania huxleyiis a bloom forming microalga that impacts the global sulfur cycle by producing large amounts of dimethylsulfoniopropionate (DMSP) and its volatile metabolic product dimethyl sulfide (DMS). Top-down regulation ofE. huxleyiblooms is attributed to viruses and grazers, however, the possible involvement of algicidal bacteria in bloom demise is still elusive. We isolated from a North AtlanticE. huxleyibloom aRoseobacterstrain,SulfitobacterD7, which exhibited algicidal effects againstE. huxleyiupon co-culturing. Both the alga and the bacterium were found to co-occur during a naturalE. huxleyibloom, therefore establishing this host-pathogen system as an attractive, ecologically relevant model for studying alga-bacterium interaction in the oceans. During interaction,SulfitobacterD7 consumed and metabolized algal DMSP to produce high amounts of methanethiol, an alternative product of DMSP catabolism. We revealed a unique strain-specific response, in whichE. huxleyistrains that exuded higher amounts of DMSP were more susceptible toSulfitobacterD7 infection. Intriguingly, exogenous application of DMSP enhanced bacterial virulence and induced susceptibility in a resistant algal strain to the bacterial pathogen. This DMSP-dependent pathogenicity was highly specific as compared to supplementation of propionate and glycerol. We propose a novel function for DMSP, in addition to its central role in mutualistic interactions, as a mediator of bacterial virulence that may regulateE. huxleyiblooms.

scholarly journals Implications of sea-ice biogeochemistry for oceanic production and emissions of dimethyl sulfide in the Arctic

2017 ◽  
Vol 14 (12) ◽  
pp. 3129-3155 ◽  
Author(s):  
Hakase Hayashida ◽  
Nadja Steiner ◽  
Adam Monahan ◽  
Virginie Galindo ◽  
Martine Lizotte ◽  
...  
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Dimethyl Sulfide ◽  
Phytoplankton Bloom ◽  
Model Simulation ◽  
Field Measurements ◽  
Sulfur Cycle ◽  
The Arctic ◽  
Model Parameters ◽  
Ocean Ecosystem

Abstract. Sea ice represents an additional oceanic source of the climatically active gas dimethyl sulfide (DMS) for the Arctic atmosphere. To what extent this source contributes to the dynamics of summertime Arctic clouds is, however, not known due to scarcity of field measurements. In this study, we developed a coupled sea ice–ocean ecosystem–sulfur cycle model to investigate the potential impact of bottom-ice DMS and its precursor dimethylsulfoniopropionate (DMSP) on the oceanic production and emissions of DMS in the Arctic. The results of the 1-D model simulation were compared with field data collected during May and June of 2010 in Resolute Passage. Our results reproduced the accumulation of DMS and DMSP in the bottom ice during the development of an ice algal bloom. The release of these sulfur species took place predominantly during the earlier phase of the melt period, resulting in an increase of DMS and DMSP in the underlying water column prior to the onset of an under-ice phytoplankton bloom. Production and removal rates of processes considered in the model are analyzed to identify the processes dominating the budgets of DMS and DMSP both in the bottom ice and the underlying water column. When openings in the ice were taken into account, the simulated sea–air DMS flux during the melt period was dominated by episodic spikes of up to 8.1 µmol m−2 d−1. Further model simulations were conducted to assess the effects of the incorporation of sea-ice biogeochemistry on DMS production and emissions, as well as the sensitivity of our results to changes of uncertain model parameters of the sea-ice sulfur cycle. The results highlight the importance of taking into account both the sea-ice sulfur cycle and ecosystem in the flux estimates of oceanic DMS near the ice margins and identify key uncertainties in processes and rates that should be better constrained by new observations.

scholarly journals In planta bacterial multi-omics analysis illuminates regulatory principles underlying plant-pathogen interactions

2019 ◽  
Author(s):  
Tatsuya Nobori ◽  
Yiming Wang ◽  
Jingni Wu ◽  
Sara Christina Stolze ◽  
Yayoi Tsuda ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Pseudomonas Syringae ◽  
Protein Level ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
Bacterial Pathogen ◽  
Bacterial Virulence ◽  
In Planta ◽  
Bacterial Gene ◽  
Global Food Security

AbstractUnderstanding how gene expression is regulated in plant pathogens is crucial for pest control and thus global food security. An integrated understanding of bacterial gene regulation in the host is dependent on multi-omic datasets, but these are largely lacking. Here, we simultaneously characterized the transcriptome and proteome of a foliar bacterial pathogen, Pseudomonas syringae, in Arabidopsis thaliana and identified a number of bacterial processes influenced by plant immunity at the mRNA and the protein level. We found instances of both concordant and discordant regulation of bacterial mRNAs and proteins. Notably, the tip component of bacterial type III secretion system was selectively suppressed by the plant salicylic acid pathway at the protein level, suggesting protein-level targeting of the bacterial virulence system by plant immunity. Furthermore, gene co-expression analysis illuminated previously unknown gene regulatory modules underlying bacterial virulence and their regulatory hierarchy. Collectively, the integrated in planta bacterial omics approach provides molecular insights into multiple layers of bacterial gene regulation that contribute to bacterial growth in planta and elucidate the role of plant immunity in controlling pathogens.

scholarly journals DMS oxidation and sulfur aerosol formation in the marine troposphere: a focus on reactive halogen and multiphase chemistry

2018 ◽  
Vol 18 (18) ◽  
pp. 13617-13637 ◽  
Author(s):  
Qianjie Chen ◽  
Tomás Sherwen ◽  
Mathew Evans ◽  
Becky Alexander
Keyword(s):  
Gas Phase ◽  
Dimethyl Sulfide ◽  
Transport Model ◽  
Removal Rate ◽  
Sulfur Cycle ◽  
Phase Reaction ◽  
Aerosol Formation ◽  
Cloud Droplets ◽  
Sulfur Chemistry ◽  
Marine Troposphere

Abstract. The oxidation of dimethyl sulfide (DMS) in the troposphere and subsequent chemical conversion into sulfur dioxide (SO2) and methane sulfonic acid (MSA) are key processes for the formation and growth of sulfur-containing aerosol and cloud condensation nuclei (CCN), but are highly simplified in large-scale models of the atmosphere. In this study, we implement a series of gas-phase and multiphase sulfur oxidation mechanisms into the Goddard Earth Observing System-Chemistry (GEOS-Chem) global chemical transport model – including two important intermediates, dimethyl sulfoxide (DMSO) and methane sulphinic acid (MSIA) – to investigate the sulfur cycle in the global marine troposphere. We found that DMS is mainly oxidized in the gas phase by OH (66 %), NO3 (16 %) and BrO (12 %) globally. DMS + BrO is important for the model's ability to reproduce the observed seasonality of surface DMS mixing ratio in the Southern Hemisphere. MSA is mainly produced from multiphase oxidation of MSIA by OH(aq) (66 %) and O3(aq) (30 %) in cloud droplets and aerosols. Aqueous-phase reaction with OH accounts for only 12 % of MSA removal globally, and a higher MSA removal rate is needed to reproduce observations of the MSA ∕ nssSO42- ratio. The modeled conversion yield of DMS into SO2 and MSA is 75 % and 15 %, respectively, compared to 91 % and 9 % in the standard model run that includes only gas-phase oxidation of DMS by OH and NO3. The remaining 10 % of DMS is lost via deposition of intermediates DMSO and MSIA. The largest uncertainties for modeling sulfur chemistry in the marine boundary layer (MBL) are unknown concentrations of reactive halogens (BrO and Cl) and OH(aq) concentrations in cloud droplets and aerosols. To reduce uncertainties in MBL sulfur chemistry, we should prioritize observations of reactive halogens and OH(aq).

scholarly journals Spatiotemporal proteomics uncovers cathepsin-dependent host cell death during bacterial infection

2018 ◽  
Author(s):  
Joel Selkrig ◽  
Nan Li ◽  
Jacob Bobonis ◽  
Annika Hausmann ◽  
Anna Sueki ◽  
...  
Keyword(s):  
Cell Death ◽  
Host Cell ◽  
Isotope Labeling ◽  
Bacterial Pathogen ◽  
Active Role ◽  
Specific Response ◽  
Proteomics Data ◽  
Macrophage Infection ◽  
Host Cell Death ◽  
Pathogen Destruction

SUMMARYImmune cells need to swiftly and effectively respond to invading pathogens. This response relies heavily on rapid protein synthesis and accurate cellular targeting to ensure pathogen destruction. In return, pathogens intercept this response to ensure their survival and proliferation. To gain insight into this dynamic interface, we combined click-chemistry with pulsed stable isotope labeling of amino acids (pSILAC-AHA) in cell culture to quantify the newly synthesised host proteome during macrophage infection with the model intracellular bacterial pathogen,Salmonella entericaTyphimurium (STm). We monitored newly synthesised proteins across different host cell compartments and infection stages, and used available proteomics data in response to lipopolysaccharide to deconvolute theSTm-specific response. Within this rich resource, we detected aberrant trafficking of lysosomal proteases to the extracellular space and the nucleus, the latter of which correlated with signatures of cell death. Pharmacological cathepsin inhibition suppressed Caspase-11 dependent macrophage cell death, thus demonstrating an active role for cathepsins duringSTm induced pyroptosis. Our study illustrates that resolving host proteome dynamics during infection can drive the discovery of biological mechanisms at the host-microbe interface.

scholarly journals Microbial conversion of inorganic carbon to dimethyl sulfide in anoxic lake sediment (Plußsee, Germany)

2010 ◽  
Vol 7 (8) ◽  
pp. 2433-2444 ◽  
Author(s):  
Y. S. Lin ◽  
V. B. Heuer ◽  
T. G. Ferdelman ◽  
K.-U. Hinrichs
Keyword(s):  
Inorganic Carbon ◽  
Dimethyl Sulfide ◽  
Dissolved Inorganic Carbon ◽  
Sulfur Cycle ◽  
Effect Of Temperature ◽  
Stoichiometric Ratio ◽  
Microbial Conversion ◽  
Methyl Group ◽  
Anoxic Environments ◽  
Reductive Pathway

Abstract. In anoxic environments, volatile methylated sulfides like methanethiol (MT) and dimethyl sulfide (DMS) link the pools of inorganic and organic carbon with the sulfur cycle. However, direct formation of methylated sulfides from reduction of dissolved inorganic carbon has previously not been demonstrated. When studying the effect of temperature on hydrogenotrophic microbial activity, we observed formation of DMS in anoxic sediment of Lake Plußsee at 55 °C. Subsequent experiments strongly suggested that the formation of DMS involves fixation of bicarbonate via a reductive pathway in analogy to methanogenesis and engages methylation of MT. DMS formation was enhanced by addition of bicarbonate and further increased when both bicarbonate and H2 were supplemented. Inhibition of DMS formation by 2-bromoethanesulfonate points to the involvement of methanogens. Compared to the accumulation of DMS, MT showed the opposite trend but there was no apparent 1:1 stoichiometric ratio between both compounds. Both DMS and MT had negative δ13C values of −62‰ and −55‰, respectively. Labeling with NaH13CO3 showed more rapid incorporation of bicarbonate into DMS than into MT. The stable carbon isotopic evidence implies that bicarbonate was fixed via a reductive pathway of methanogenesis, and the generated methyl coenzyme M became the methyl donor for MT methylation. Neither DMS nor MT accumulation were stimulated by addition of the methyl-group donors methanol and syringic acid or by the methyl-group acceptor hydrogen sulphide. The source of MT was further investigated in a H235S labeling experiment, which demonstrated a microbially-mediated process of hydrogen sulfide methylation to MT that accounted for only <10% of the accumulation rates of DMS. Therefore, the major source of the 13C-depleted MT was neither bicarbonate nor methoxylated aromatic compounds. Other possibilities for isotopically depleted MT, such as other organic precursors like methionine, are discussed. This DMS-forming pathway may be relevant for anoxic environments such as hydrothermally influenced sediments and fluids and sulfate-methane transition zones in marine sediments.

scholarly journals Dimethyl sulfide in the summertime Arctic atmosphere: measurements and source sensitivity simulations

2016 ◽  
Vol 16 (11) ◽  
pp. 6665-6680 ◽  
Author(s):  
Emma L. Mungall ◽  
Betty Croft ◽  
Martine Lizotte ◽  
Jennie L. Thomas ◽  
Jennifer G. Murphy ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Transport Model ◽  
Sulfur Cycle ◽  
Oxidation Products ◽  
The Arctic ◽  
High Time Resolution ◽  
Study Region ◽  
Baffin Bay ◽  
Mixing Ratios ◽  
Arctic Atmosphere

Abstract. Dimethyl sulfide (DMS) plays a major role in the global sulfur cycle. In addition, its atmospheric oxidation products contribute to the formation and growth of atmospheric aerosol particles, thereby influencing cloud condensation nuclei (CCN) populations and thus cloud formation. The pristine summertime Arctic atmosphere is strongly influenced by DMS. However, atmospheric DMS mixing ratios have only rarely been measured in the summertime Arctic. During July–August, 2014, we conducted the first high time resolution (10 Hz) DMS mixing ratio measurements for the eastern Canadian Archipelago and Baffin Bay as one component of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments (NETCARE). DMS mixing ratios ranged from below the detection limit of 4 to 1155 pptv (median 186 pptv) during the 21-day shipboard campaign. A transfer velocity parameterization from the literature coupled with coincident atmospheric and seawater DMS measurements yielded air–sea DMS flux estimates ranging from 0.02 to 12 µmol m−2 d−1. Air-mass trajectory analysis using FLEXPART-WRF and sensitivity simulations with the GEOS-Chem chemical transport model indicated that local sources (Lancaster Sound and Baffin Bay) were the dominant contributors to the DMS measured along the 21-day ship track, with episodic transport from the Hudson Bay System. After adjusting GEOS-Chem oceanic DMS values in the region to match measurements, GEOS-Chem reproduced the major features of the measured time series but was biased low overall (2–1006 pptv, median 72 pptv), although within the range of uncertainty of the seawater DMS source. However, during some 1–2 day periods the model underpredicted the measurements by more than an order of magnitude. Sensitivity tests indicated that non-marine sources (lakes, biomass burning, melt ponds, and coastal tundra) could make additional episodic contributions to atmospheric DMS in the study region, although local marine sources of DMS dominated. Our results highlight the need for both atmospheric and seawater DMS data sets with greater spatial and temporal resolution, combined with further investigation of non-marine DMS sources for the Arctic.

scholarly journals The Role of Dimethyl Sulfide(DMS) on the Global Sulfur Cycle and its Microbial Transformation.

1999 ◽  
Vol 73 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Masae HORINOUCHI ◽  
Hideaki NOJIRI ◽  
Hisakazu YAMANE ◽  
Toshio OMORI
Keyword(s):  
Dimethyl Sulfide ◽  
Microbial Transformation ◽  
Sulfur Cycle

Estimate of the Contribution of Biologically Produced Dimethyl Sulfide to the Global Sulfur Cycle

Science ◽  
1977 ◽  
Vol 196 (4290) ◽  
pp. 647-648 ◽  
Author(s):  
P. J. MAROULIS ◽  
A. R. BANDY
Keyword(s):  
Dimethyl Sulfide ◽  
Sulfur Cycle

scholarly journals Two Distinct Aerobic Methionine Salvage Pathways Generate Volatile Methanethiol inRhodopseudomonas palustris

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Anthony R. Miller ◽  
Justin A. North ◽  
John A. Wildenthal ◽  
F. Robert Tabita
Keyword(s):  
Rhodospirillum Rubrum ◽  
Dimethyl Sulfide ◽  
Rhodopseudomonas Palustris ◽  
Calvin Cycle ◽  
Sulfur Cycle ◽  
Dihydroxyacetone Phosphate ◽  
Content Type ◽  
Salvage Pathways ◽  
Sulfur Containing ◽  
Methionine Salvage

ABSTRACT5′-Methyl-thioadenosine (MTA) is a dead-end, sulfur-containing metabolite and cellular inhibitor that arises fromS-adenosyl-l-methionine-dependent reactions. Recent studies have indicated that there are diverse bacterialmethioninesalvagepathways (MSPs) for MTA detoxification and sulfur salvage. Here, via a combination of gene deletions and directed metabolite detection studies, we report that under aerobic conditions the facultatively anaerobic bacteriumRhodopseudomonas palustrisemploys both an MTA-isoprenoid shunt identical to that previously described inRhodospirillum rubrumand a second novel MSP, both of which generate a methanethiol intermediate. The additionalR. palustrisaerobic MSP, a dihydroxyacetone phosphate (DHAP)-methanethiol shunt, initially converts MTA to 2-(methylthio)ethanol and DHAP. This is identical to the initial steps of the recently reported anaerobic ethylene-forming MSP, the DHAP-ethylene shunt. The aerobic DHAP-methanethiol shunt then further metabolizes 2-(methylthio)ethanol to methanethiol, which can be directly utilized by O-acetyl-l-homoserine sulfhydrylase to regenerate methionine. This is in contrast to the anaerobic DHAP-ethylene shunt, which metabolizes 2-(methylthio)ethanol to ethylene and an unknown organo-sulfur intermediate, revealing functional diversity in MSPs utilizing a 2-(methylthio)ethanol intermediate. When MTA was fed to aerobically growing cells, the rate of volatile methanethiol release was constant irrespective of the presence of sulfate, suggesting a general housekeeping function for these MSPs up through the methanethiol production step. Methanethiol and dimethyl sulfide (DMS), two of the most important compounds of the global sulfur cycle, appear to arise not only from marine ecosystems but from terrestrial ones as well. These results reveal a possible route by which methanethiol might be biologically produced in soil and freshwater environments.IMPORTANCEBiologically available sulfur is often limiting in the environment. Therefore, many organisms have developed methionine salvage pathways (MSPs) to recycle sulfur-containing by-products back into the amino acid methionine. The metabolically versatile bacteriumRhodopseudomonas palustrisis unusual in that it possesses two RuBisCOs and two RuBisCO-like proteins. While RuBisCO primarily serves as the carbon fixation enzyme of the Calvin cycle, RuBisCOs and certain RuBisCO-like proteins have also been shown to function in methionine salvage. This work establishes that only one of theR. palustrisRuBisCO-like proteins functions as part of an MSP. Moreover, in the presence of oxygen, to salvage sulfur,R. palustrisemploys two pathways, both of which result in production of volatile methanethiol, a key compound of the global sulfur cycle. When total available sulfur was plentiful, methanethiol was readily released into the environment. However, when sulfur became limiting, methanethiol release decreased, presumably due to methanethiol utilization to regenerate needed methionine.

Sign in / Sign up

Export Citation Format

Share Document