scholarly journals Dynamics of Heterotrophic Bacterial Assemblages withinSynechococcusCultures

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Qiang Zheng ◽  
Yu Wang ◽  
Rui Xie ◽  
Andrew S. Lang ◽  
Yanting Liu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Heterotrophic Bacteria ◽  
Biogeochemical Cycling ◽  
Distribution Patterns ◽  
Culture Period ◽  
Interspecies Interactions ◽  
Carbon Utilization ◽  
Free Living ◽  
Content Type ◽  
Culture Growth

ABSTRACTInteractions between photoautotrophic and heterotrophic microorganisms are central to the marine microbial ecosystem. Lab cultures of one of the dominant marine photoautotrophs,Synechococcus, have historically been difficult to render axenic, presumably because these bacteria depend upon other organisms to grow under these conditions. These tight associations betweenSynechococcusand heterotrophic bacteria represent a good relevant system to study interspecies interactions. Ten individualSynechococcusstrains, isolated from eutrophic and oligotrophic waters, were chosen for investigation. Four to six dominant associated heterotrophic bacteria were detected in the liquid cultures of eachSynechococcusisolate, comprising members of theCytophaga-Flavobacteria-Bacteroides(CFB) group (mainly fromFlavobacterialesandCytophagales),Alphaproteobacteria(mainly from theRoseobacterclade),Gammaproteobacteria(mainly from theAlteromonadalesandPseudomonadales), andActinobacteria. The presence of the CFB group,Gammaproteobacteria, andActinobacteriashowed clear geographic patterns related to the isolation environments of theSynechococcusbacteria. An investigation of the population dynamics within a growing culture (XM-24) of one of the isolates, including an evaluation of the proportions of cells that were free-living versus aggregated/attached, revealed interesting patterns for different bacterial groups. InSynechococcussp. strain XM-24 culture, flavobacteria, which was the most abundant group throughout the culture period, tended to be aggregated or attached to theSynechococcuscells, whereas the actinobacteria demonstrated a free-living lifestyle, and roseobacters displayed different patterns depending on the culture growth phase. Factors contributing to these succession patterns for the heterotrophs likely include interactions among the culture community members, their relative abilities to utilize different compounds produced bySynechococcuscells and changes in the compounds released as culture growth proceeds, and their responses to other changes in the environmental conditions throughout the culture period.IMPORTANCEMarine microbes exist within an interactive ecological network, and studying their interactions is an important part of understanding their roles in global biogeochemical cycling and the determinants of microbial diversity. In this study, the dynamic relationships betweenSynechococcusspp. and their associated heterotrophic bacteria were investigated.Synechococcus-associated heterotrophic bacteria had similar geographic distribution patterns as their “host” and displayed different lifestyles (free-living versus attached/aggregated) according to theSynechococcusculture growth phases. Combined organic carbon composition and bacterial lifestyle data indicated a potential for succession in carbon utilization patterns by the dominant associated heterotrophic bacteria. Comprehending the interactions between photoautotrophs and heterotrophs and the patterns of organic carbon excretion and utilization is critical to understanding their roles in oceanic biogeochemical cycling.

scholarly journals Transcriptional Control in Marine Copiotrophic and Oligotrophic Bacteria with Streamlined Genomes

2016 ◽  
Vol 82 (19) ◽  
pp. 6010-6018 ◽  
Author(s):  
Matthew T. Cottrell ◽  
David L. Kirchman
Keyword(s):  
Marine Bacteria ◽  
Environmental Conditions ◽  
Transcriptional Control ◽  
Heterotrophic Bacteria ◽  
Content Type ◽  
Oligotrophic Bacteria ◽  
Protein Encoding ◽  
Culture Growth ◽  
Ruegeria Pomeroyi ◽  
And Shifts

ABSTRACTBacteria often respond to environmental stimuli using transcriptional control, but this may not be the case for marine bacteria such as “CandidatusPelagibacter ubique,” a cultivated representative of the SAR11 clade, the most abundant organism in the ocean. This bacterium has a small, streamlined genome and an unusually low number of transcriptional regulators, suggesting that transcriptional control is low inPelagibacterand limits its response to environmental conditions. Transcriptome sequencing during batch culture growth revealed that only 0.1% of protein-encoding genes appear to be under transcriptional control inPelagibacterand in another oligotroph (SAR92) whereas >10% of genes were under transcriptional control in the copiotrophsPolaribactersp. strain MED152 andRuegeria pomeroyi. When growth levels changed, transcript levels remained steady inPelagibacterand SAR92 but shifted in MED152 andR. pomeroyi. Transcript abundances per cell, determined using an internal RNA sequencing standard, were low (<1 transcript per cell) for all but a few of the most highly transcribed genes in all four taxa, and there was no correlation between transcript abundances per cell and shifts in the levels of transcription. These results suggest that low transcriptional control contributes to the success ofPelagibacterand possibly other oligotrophic microbes that dominate microbial communities in the oceans.IMPORTANCEDiverse heterotrophic bacteria drive biogeochemical cycling in the ocean. The most abundant types of marine bacteria are oligotrophs with small, streamlined genomes. The metabolic controls that regulate the response of oligotrophic bacteria to environmental conditions remain unclear. Our results reveal that transcriptional control is lower in marine oligotrophic bacteria than in marine copiotrophic bacteria. Although responses of bacteria to environmental conditions are commonly regulated at the level of transcription, metabolism in the most abundant bacteria in the ocean appears to be regulated by other mechanisms.

scholarly journals Thermoanaerobacter thermohydrosulfuricus WC1 Shows Protein Complement Stability during Fermentation of Key Lignocellulose-Derived Substrates

2013 ◽  
Vol 80 (5) ◽  
pp. 1602-1615 ◽  
Author(s):  
Tobin J. Verbeke ◽  
Vic Spicer ◽  
Oleg V. Krokhin ◽  
Xiangli Zhang ◽  
John J. Schellenberg ◽  
...  
Keyword(s):  
Consolidated Bioprocessing ◽  
Expression Patterns ◽  
Distribution Patterns ◽  
Product Distribution ◽  
Biofuel Production ◽  
Gene Products ◽  
Label Free ◽  
Carbon Utilization ◽  
Content Type ◽  
Lignocellulosic Biofuel

ABSTRACTThermoanaerobacterspp. have long been considered suitableClostridium thermocellumcoculture partners for improving lignocellulosic biofuel production through consolidated bioprocessing. However, studies using “omic”-based profiling to better understand carbon utilization and biofuel producing pathways have been limited to only a few strains thus far. To better characterize carbon and electron flux pathways in the recently isolated, xylanolytic strain,Thermoanaerobacter thermohydrosulfuricusWC1, label-free quantitative proteomic analyses were combined with metabolic profiling. SWATH-MS proteomic analysis quantified 832 proteins in each of six proteomes isolated from mid-exponential-phase cells grown on xylose, cellobiose, or a mixture of both. Despite encoding genes consistent with a carbon catabolite repression network observed in other Gram-positive organisms, simultaneous consumption of both substrates was observed. Lactate was the major end product of fermentation under all conditions despite the high expression of gene products involved with ethanol and/or acetate synthesis, suggesting that carbon flux in this strain may be controlled via metabolite-based (allosteric) regulation or is constrained by metabolic bottlenecks. Cross-species “omic” comparative analyses confirmed similar expression patterns for end-product-forming gene products across diverseThermoanaerobacterspp. It also identified differences in cofactor metabolism, which potentially contribute to differences in end-product distribution patterns between the strains analyzed. The analyses presented here improve our understanding ofT. thermohydrosulfuricusWC1 metabolism and identify important physiological limitations to be addressed in its development as a biotechnologically relevant strain in ethanologenic designer cocultures through consolidated bioprocessing.

scholarly journals Proteomic Response of Three Marine Ammonia-Oxidizing Archaea to Hydrogen Peroxide and Their Metabolic Interactions with a Heterotrophic Alphaproteobacterium

mSystems ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Barbara Bayer ◽  
Claus Pelikan ◽  
Meriel J. Bittner ◽  
Thomas Reinthaler ◽  
Martin Könneke ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Carbon ◽  
Heterotrophic Bacteria ◽  
Global Ocean ◽  
Physiological Status ◽  
Marine Environments ◽  
Content Type ◽  
Ammonia Oxidizing Archaea ◽  
Metabolic Interactions ◽  
Detoxifying Enzyme

ABSTRACT Ammonia-oxidizing archaea (AOA) play an important role in the nitrogen cycle and account for a considerable fraction of the prokaryotic plankton in the ocean. Most AOA lack the hydrogen peroxide (H2O2)-detoxifying enzyme catalase, and some AOA have been shown to grow poorly under conditions of exposure to H2O2. However, differences in the degrees of H2O2 sensitivity of different AOA strains, the physiological status of AOA cells exposed to H2O2, and their molecular response to H2O2 remain poorly characterized. Further, AOA might rely on heterotrophic bacteria to detoxify H2O2, and yet the extent and variety of costs and benefits involved in these interactions remain unclear. Here, we used a proteomics approach to compare the protein profiles of three Nitrosopumilus strains grown in the presence and absence of catalase and in coculture with the heterotrophic alphaproteobacterium Oceanicaulis alexandrii. We observed that most proteins detected at a higher relative abundance in H2O2-exposed Nitrosopumilus cells had no known function in oxidative stress defense. Instead, these proteins were putatively involved in the remodeling of the extracellular matrix, which we hypothesize to be a strategy limiting the influx of H2O2 into the cells. Using RNA-stable isotope probing, we confirmed that O. alexandrii cells growing in coculture with the Nitrosopumilus strains assimilated Nitrosopumilus-derived organic carbon, suggesting that AOA could recruit H2O2-detoxifying bacteria through the release of labile organic matter. Our results contribute new insights into the response of AOA to H2O2 and highlight the potential ecological importance of their interactions with heterotrophic free-living bacteria in marine environments. IMPORTANCE Ammonia-oxidizing archaea (AOA) are the most abundant chemolithoautotrophic microorganisms in the oxygenated water column of the global ocean. Although H2O2 appears to be a universal by-product of aerobic metabolism, genes encoding the hydrogen peroxide (H2O2)-detoxifying enzyme catalase are largely absent in genomes of marine AOA. Here, we provide evidence that closely related marine AOA have different degrees of sensitivity to H2O2, which may contribute to niche differentiation between these organisms. Furthermore, our results suggest that marine AOA rely on H2O2 detoxification during periods of high metabolic activity and release organic compounds, thereby potentially attracting heterotrophic prokaryotes that provide this missing function. In summary, this report provides insights into the metabolic interactions between AOA and heterotrophic bacteria in marine environments and suggests that AOA play an important role in the biogeochemical carbon cycle by making organic carbon available for heterotrophic microorganisms.

scholarly journals Influence of Light on Carbon Utilization in Aerobic Anoxygenic Phototrophs

2012 ◽  
Vol 78 (20) ◽  
pp. 7414-7419 ◽  
Author(s):  
Dzmitry Hauruseu ◽  
Michal Koblížek
Keyword(s):  
Organic Carbon ◽  
Carbon Fixation ◽  
Electron Flow ◽  
High Irradiance ◽  
Carbon Utilization ◽  
Additional Energy ◽  
Content Type ◽  
Anoxygenic Phototrophs ◽  
Aerobic Anoxygenic Phototrophs ◽  
Light Intensities

ABSTRACTAerobic anoxygenic phototrophs contain photosynthetic reaction centers composed of bacteriochlorophyll. These organisms are photoheterotrophs, as they require organic carbon substrates for their growth whereas light-derived energy has only an auxiliary function. To establish the contribution of light energy to their metabolism, we grew the phototrophic strainErythrobactersp. NAP1 in a carbon-limited chemostat regimen on defined carbon sources (glutamate, pyruvate, acetate, and glucose) under conditions of different light intensities. When grown in a light-dark cycle, these bacteria accumulated 25% to 110% more biomass in terms of carbon than cultures grown in the dark. Cultures grown on glutamate accumulated the most biomass at moderate light intensities of 50 to 150 μmol m−2s−1but were inhibited at higher light intensities. In the case of pyruvate, we did not find any inhibition of growth by high irradiance. The extent of anaplerotic carbon fixation was detemined by radioactive bicarbonate incorporation assays. While the carboxylation activity provided 4% to 11% of the cellular carbon in the pyruvate-grown culture, in the glutamate-grown cells it provided only approximately 1% of the carbon. Additionally, we tested the effect of light on respiration and photosynthetic electron flow. With increasing light intensity, respiration decreased to approximately 25% of its dark value and was replaced by photophosphorylation. The additional energy from light allows the aerobic anoxygenic phototrophs to accumulate the supplied organic carbon which would otherwise be respired. The higher efficiency of organic carbon utilization may provide an important competitive advantage during growth under carbon-limited conditions.

scholarly journals Pseudomonas aeruginosa PA14 Enhances the Efficacy of Norfloxacin against Staphylococcus aureus Newman Biofilms

2020 ◽  
Vol 202 (18) ◽  
Author(s):  
Giulia Orazi ◽  
Fabrice Jean-Pierre ◽  
George A. O’Toole
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Respiratory Infections ◽  
Multiple Infection ◽  
Bacterial Biofilms ◽  
Interspecies Interactions ◽  
Chronic Infections ◽  
Content Type

ABSTRACT The thick mucus within the airways of individuals with cystic fibrosis (CF) promotes frequent respiratory infections that are often polymicrobial. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent pathogens that cause CF pulmonary infections, and both are among the most common etiologic agents of chronic wound infections. Furthermore, the ability of P. aeruginosa and S. aureus to form biofilms promotes the establishment of chronic infections that are often difficult to eradicate using antimicrobial agents. In this study, we found that multiple LasR-regulated exoproducts of P. aeruginosa, including 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), siderophores, phenazines, and rhamnolipids, likely contribute to the ability of P. aeruginosa PA14 to shift S. aureus Newman norfloxacin susceptibility profiles. Here, we observe that exposure to P. aeruginosa exoproducts leads to an increase in intracellular norfloxacin accumulation by S. aureus. We previously showed that P. aeruginosa supernatant dissipates the S. aureus membrane potential, and furthermore, depletion of the S. aureus proton motive force recapitulates the effect of the P. aeruginosa PA14 supernatant on shifting norfloxacin sensitivity profiles of biofilm-grown S. aureus Newman. From these results, we hypothesize that exposure to P. aeruginosa PA14 exoproducts leads to increased uptake of the drug and/or an impaired ability of S. aureus Newman to efflux norfloxacin. Surprisingly, the effect observed here of P. aeruginosa PA14 exoproducts on S. aureus Newman susceptibility to norfloxacin seemed to be specific to these strains and this antibiotic. Our results illustrate that microbially derived products can alter the ability of antimicrobial agents to kill bacterial biofilms. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are frequently coisolated from multiple infection sites, including the lungs of individuals with cystic fibrosis (CF) and nonhealing diabetic foot ulcers. Coinfection with P. aeruginosa and S. aureus has been shown to produce worse outcomes compared to infection with either organism alone. Furthermore, the ability of these pathogens to form biofilms enables them to cause persistent infection and withstand antimicrobial therapy. In this study, we found that P. aeruginosa-secreted products dramatically increase the ability of the antibiotic norfloxacin to kill S. aureus biofilms. Understanding how interspecies interactions alter the antibiotic susceptibility of bacterial biofilms may inform treatment decisions and inspire the development of new therapeutic strategies.

scholarly journals Impact of aquaculture on distribution of dissolved organic matter in coastal Jeju Island, Korea, based on absorption and fluorescence spectroscopy

2021 ◽  
Author(s):  
Jeonghyun Kim ◽  
Yeseul Kim ◽  
Sung Eun Park ◽  
Tae-Hoon Kim ◽  
Bong-Guk Kim ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Fluorescence Spectroscopy ◽  
Dissolved Organic Matter ◽  
Coastal Water ◽  
Coastal Region ◽  
Principal Component ◽  
Distribution Patterns ◽  
Organic Pollution ◽  
Jeju Island

AbstractIn Jeju Island, multiple land-based aquafarms were fully operational along most coastal region. However, the effect of effluent on distribution and behaviours of dissolved organic matter (DOM) in the coastal water are still unknown. To decipher characteristics of organic pollution, we compared physicochemical parameters with spectral optical properties near the coastal aquafarms in Jeju Island. Absorption spectra were measured to calculate the absorption coefficient, spectral slope coefficient, and specific UV absorbance. Fluorescent DOM was analysed using fluorescence spectroscopy coupled with parallel factor analysis. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were measured using high-temperature catalytic oxidation. The DOC concentration near the discharge outlet was twice higher than that in natural groundwater, and the TDN concentration exponentially increased close to the outlet. These distribution patterns indicate that aquafarms are a significant source of DOM. Herein, principal component analysis was applied to categorise the DOM origins. There were two distinct groups, namely, aquaculture activity for TDN with humic-like and high molecular weights DOM (PC1: 48.1%) and natural biological activity in the coastal water for DOC enrichment and protein-like DOM (PC2: 18.8%). We conclude that the aquafarms significantly discharge organic nitrogen pollutants and provoke in situ production of organic carbon. Furthermore, these findings indicate the potential of optical techniques for the efficient monitoring of anthropogenic organic pollutants from aquafarms worldwide.

scholarly journals Function of the Pyruvate Oxidase-Lactate Oxidase Cascade in Interspecies Competition between Streptococcus oligofermentans and Streptococcus mutans

2012 ◽  
Vol 78 (7) ◽  
pp. 2120-2127 ◽  
Author(s):  
Lei Liu ◽  
Huichun Tong ◽  
Xiuzhu Dong
Keyword(s):  
Stationary Phase ◽  
Streptococcus Mutans ◽  
Growth Phase ◽  
Large Degree ◽  
Interspecies Interactions ◽  
Lactate Oxidase ◽  
Interspecies Competition ◽  
Pyruvate Oxidase ◽  
Content Type

ABSTRACTComplex interspecies interactions occur constantly between oral commensals and the opportunistic pathogenStreptococcus mutansin dental plaque. Previously, we showed that oral commensalStreptococcus oligofermentanspossesses multiple enzymes for H2O2production, especially lactate oxidase (Lox), allowing it to out-competeS. mutans. In this study, through extensive biochemical and genetic studies, we identified a pyruvate oxidase (pox) gene inS. oligofermentans. Apoxdeletion mutant completely lost Pox activity, while ectopically expressedpoxrestored activity. Pox was determined to produce most of the H2O2in the earlier growth phase and log phase, while Lox mainly contributed to H2O2production in stationary phase. Bothpoxandloxwere expressed throughout the growth phase, while expression of theloxgene increased by about 2.5-fold when cells entered stationary phase. Since lactate accumulation occurred to a large degree in stationary phase, the differential Pox- and Lox-generated H2O2can be attributed to differential gene expression and substrate availability. Interestingly, inactivation ofpoxcauses a dramatic reduction in H2O2production from lactate, suggesting a synergistic action of the two oxidases in converting lactate into H2O2. In anin vitrotwo-species biofilm experiment, thepoxmutant ofS. oligofermentansfailed to inhibitS. mutanseven thoughloxwas active. In summary,S. oligofermentansdevelops a Pox-Lox synergy strategy to maximize its H2O2formation so as to win the interspecies competition.

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