scholarly journals Microbial iron uptake in the naturally fertilized waters in the vicinity of the Kerguelen Islands: phytoplankton–bacteria interactions

2015 ◽  
Vol 12 (6) ◽  
pp. 1893-1906 ◽  
Author(s):  
M. Fourquez ◽  
I. Obernosterer ◽  
D. M. Davies ◽  
T. W. Trull ◽  
S. Blain
Keyword(s):  
Microbial Community ◽  
Iron Uptake ◽  
Heterotrophic Bacteria ◽  
Size Fraction ◽  
Kerguelen Islands ◽  
Carbon Cycles ◽  
Carbon Biomass ◽  
Uptake Rates ◽  
Fe Uptake ◽  
Tightly Coupled

Abstract. Iron (Fe) uptake by the microbial community and the contribution of three different size fractions was determined during spring phytoplankton blooms in the naturally Fe-fertilized area off the Kerguelen Islands (KEOPS2). Total Fe uptake in surface waters was on average 34 ± 6 pmol Fe L-1 d-1, and microplankton (> 25 μm size fraction; 40–69%) and pico-nanoplankton (0.8–25 μm size fraction; 29–59%) were the main contributors. The contribution of heterotrophic bacteria (0.2–0.8 μm size fraction) to total Fe uptake was low at all stations (1–2%). Iron uptake rates normalized to carbon biomass were highest for pico-nanoplankton above the Kerguelen Plateau and for microplankton in the downstream plume. We also investigated the potential competition between heterotrophic bacteria and phytoplankton for the access to Fe. Bacterial Fe uptake rates normalized to carbon biomass were highest in incubations with bacteria alone, and dropped in incubations containing other components of the microbial community. Interestingly, the decrease in bacterial Fe uptake rate (up to 26-fold) was most pronounced in incubations containing pico-nanoplankton and bacteria, while the bacterial Fe uptake was only reduced by 2- to 8-fold in incubations containing the whole community (bacteria + pico-nanoplankton + microplankton). In Fe-fertilized waters, the bacterial Fe uptake rates normalized to carbon biomass were positively correlated with primary production. Taken together, these results suggest that heterotrophic bacteria are outcompeted by small-sized phytoplankton cells for the access to Fe during the spring bloom development, most likely due to the limitation by organic matter. We conclude that the Fe and carbon cycles are tightly coupled and driven by a complex interplay of competition and synergy between different members of the microbial community.

scholarly journals Microbial iron uptake in the naturally fertilized waters in the vicinity of Kerguelen Islands: phytoplankton–bacteria interactions

2014 ◽  
Vol 11 (10) ◽  
pp. 15053-15086 ◽  
Author(s):  
M. Fourquez ◽  
I. Obernosterer ◽  
D. M. Davies ◽  
T. W. Trull ◽  
S. Blain
Keyword(s):  
Microbial Community ◽  
Iron Uptake ◽  
Heterotrophic Bacteria ◽  
Size Fraction ◽  
Kerguelen Islands ◽  
Carbon Cycles ◽  
Carbon Biomass ◽  
Uptake Rates ◽  
Fe Uptake ◽  
Tightly Coupled

Abstract. Iron (Fe) uptake by the microbial community and the contribution of three different size-fractions was determined during spring phytoplankton blooms in the naturally Fe fertilized area off Kerguelen Islands (KEOPS2). Total Fe uptake in surface waters was on average 34 ± 6 pmol Fe L−1 d−1, and microplankton (>25 μm size-fraction; 40–69%) and pico-nanoplankton (0.8–25 μm size-fraction; 29–59%) were the main contributors. The share of heterotrophic bacteria (0.2–0.8 μm size-fraction) to total Fe uptake was low at all stations (1–2%). Iron uptake rates normalized to carbon biomass were highest for pico-nanoplankton above the Kerguelen plateau and for microplankton in the downstream plume. We also investigated the potential competition between heterotrophic bacteria and phytoplankton for the access to Fe. Bacterial Fe uptake rates normalized to carbon biomass were highest when bacteria were incubated in the absence of both micro- and pico-nanoplankton. The absence of microplankton resulted in a decrease in bacterial Fe uptake rates by up to 20-fold, while in incubations with the whole microbial community bacterial uptake rates were reduced by 2- to 8-fold. In Fe-fertilized waters, the bacterial Fe uptake rates normalized to carbon biomass were positively correlated with primary production. Taken together, these results demonstrate that heterotrophic bacteria are outcompeted by small sized phytoplankton cells for the access to Fe during the spring bloom development, most likely due to the limitation by organic matter. We conclude that the Fe and carbon cycles are tightly coupled and driven by a~complex interplay of competition and synergy between different members of the microbial community.

scholarly journals Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off Kerguelen Islands

2014 ◽  
Vol 11 (11) ◽  
pp. 15733-15752 ◽  
Author(s):  
I. Obernosterer ◽  
M. Fourquez ◽  
S. Blain
Keyword(s):  
Trace Metal ◽  
Heterotrophic Bacteria ◽  
Surface Mixed Layer ◽  
Kerguelen Islands ◽  
Uptake Rates ◽  
Fe Uptake ◽  
Limiting Nutrient ◽  
Heterotrophic Metabolism ◽  
Heterotrophic Production

Abstract. It has univocally been shown that iron (Fe) is the primary limiting nutrient for phytoplankton metabolism in High Nutrient Low Chlorophyll (HNLC) oceans, yet, the question of how this trace metal affects heterotrophic microbial activity is far less understood. We investigated the role of Fe for bacterial heterotrophic production and growth at three contrasting sites in the naturally Fe-fertilized region east of Kerguelen Islands and at one site in HNLC waters during the KEOPS2 (Kerguelen Ocean and Plateau Compared Study 2) cruise in spring 2011. We performed dark incubations of natural microbial communities amended either with iron (Fe, as FeCl3), or carbon (C, as trace-metal clean glucose), or a combination of both, and followed bacterial abundance and heterotrophic production for up to 7 days. Our results show that single and combined additions of Fe and C stimulated bulk and cell-specific bacterial production at all sites, while bacterial growth was enhanced only in two out of four occasions. The extent of stimulation of bulk bacterial heterotrophic production by single Fe or C additions increased with increasing in situ bacterial Fe uptake rates in the surface mixed layer. Our results provide evidence that both Fe and C are present at limiting concentrations for bacterial heterotrophic activity, in HNLC and fertilized regions, in spring. The observation that the extent of stimulation by both elements was related to Fe-uptake rates highlights the tight interaction between the C- and Fe-cycles through bacterial heterotrophic metabolism in the Southern Ocean.

scholarly journals Iron Uptake by Toxic and Nontoxic Strains of Microcystis aeruginosa

2011 ◽  
Vol 77 (19) ◽  
pp. 7068-7071 ◽  
Author(s):  
Manabu Fujii ◽  
Andrew L. Rose ◽  
T. David Waite
Keyword(s):  
Microcystis Aeruginosa ◽  
Iron Uptake ◽  
Genetically Engineered ◽  
Uptake Kinetics ◽  
Wild Type ◽  
Short Term ◽  
Content Type ◽  
Uptake Rates ◽  
Fe Uptake

ABSTRACTIron uptake by microcystin-producing and non-microcystin-producing strains ofMicrocystis aeruginosawas investigated through short-term uptake assays. Although strain-specific differences were observed, the siderophore-independent Fe uptake kinetics were essentially similar (e.g., maximum uptake rates of 2.0 to 3.3 amol·cell−1·h−1) for the wild-type toxic strain PCC7806 and a genetically engineered mutant unable to produce microcystin.

scholarly journals Fe and C co-limitation of heterotrophic bacteria in the naturally fertilized region off the Kerguelen Islands

2015 ◽  
Vol 12 (6) ◽  
pp. 1983-1992 ◽  
Author(s):  
I. Obernosterer ◽  
M. Fourquez ◽  
S. Blain
Keyword(s):  
Trace Metal ◽  
Bacterial Production ◽  
Bacterial Abundance ◽  
Heterotrophic Bacteria ◽  
Kerguelen Islands ◽  
High Nutrient ◽  
Limiting Nutrient ◽  
Heterotrophic Metabolism ◽  
Heterotrophic Production

Abstract. It has been univocally shown that iron (Fe) is the primary limiting nutrient for phytoplankton metabolism in high-nutrient, low-chlorophyll (HNLC) waters, yet the question of how this trace metal affects heterotrophic microbial activity is far less understood. We investigated the role of Fe for bacterial heterotrophic production and growth at three contrasting sites in the naturally Fe-fertilized region east of the Kerguelen Islands and at one site in HNLC waters during the KEOPS2 (Kerguelen Ocean and Plateau Compared Study 2) cruise in spring 2011. We performed dark incubations of natural microbial communities amended either with iron (Fe, as FeCl3) or carbon (C, as trace-metal clean glucose), or a combination of both, and followed bacterial abundance and heterotrophic production for up to 7 days. Our results show that single and combined additions of Fe and C stimulated bulk and cell-specific bacterial production at the Fe-fertilized sites, while in HNLC waters only combined additions resulted in significant increases in these parameters. Bacterial abundance was enhanced in two out of the three experiments performed in Fe-fertilized waters but did not respond to Fe or C additions in HNLC waters. Our results provide evidence that both Fe and C are present at limiting concentrations for bacterial heterotrophic activity in the naturally fertilized region off the Kerguelen Islands in spring, while bacteria were co-limited by these elements in HNLC waters. These results shed new light on the role of Fe in bacterial heterotrophic metabolism in regions of the Southern Ocean that receive variable Fe inputs.

Heterotrophic Bacterial Community Structure of Multistage Biofilters in a Commercial Pufferfish Takifugu rubripes RAS

2013 ◽  
Vol 726-731 ◽  
pp. 1621-1627 ◽  
Author(s):  
Zhu Chen ◽  
Ying Liu ◽  
Liang Zi Liu ◽  
Xiao Jing Wang ◽  
Zhi Pei Liu ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Bacterial Community ◽  
Bacterial Community Structure ◽  
Heterotrophic Bacteria ◽  
Diversity Index ◽  
Community Diversity ◽  
Takifugu Rubripes ◽  
Recirculating Aquaculture ◽  
Microbial Resources

The success of a recirculating aquaculture system (RAS) greatly depends on the structure, dynamics and activities of microbial community. Heterotrophic bacteria as the major members play various roles. The heterotrophic bacterial community structure in threestaged biofilters was studied using four different media. 228 isolates belonging to 77species were obtained and affiliated toGammaproteobacteria,Alphaproteobacteria,Bacteroidetes,Firmicutes,ActinobacteriaandBetaproteobacteria.Gammaproteobacteriawas the predominant group. The concurrence was found between potential pathogens (VibrioandShewanella) and probiotics (BacillusandPseudomonas). On the basis of community diversity index, we could infer that differences existed between stages, and the diversity index increased along the biofilters. A comprehensive understanding of microbial community in RAS will be in favor of utilization of microbial resources and optimizing the culture systems' operation.

scholarly journals The influence of aggregate size fraction and horizon position on microbial community composition

2018 ◽  
Vol 127 ◽  
pp. 19-29 ◽  
Author(s):  
Aaron Fox ◽  
Israel Ikoyi ◽  
Gemma Torres-Sallan ◽  
Gary Lanigan ◽  
Achim Schmalenberger ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Microbial Community Composition ◽  
Size Fraction ◽  
Aggregate Size

scholarly journals The Combined Strategy for iron uptake is not exclusive to domesticated rice (Oryza sativa)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andriele Wairich ◽  
Ben Hur Neves de Oliveira ◽  
Ezequiel Barth Arend ◽  
Guilherme Leitão Duarte ◽  
Lucas Roani Ponte ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Iron Uptake ◽  
Wild Progenitor ◽  
Flooded Soils ◽  
Transcriptomic Response ◽  
Fe Uptake ◽  
Aa Genome ◽  
Combined Strategy ◽  
Strategy I ◽  
Uptake Mechanisms

Abstract Iron (Fe) is an essential micronutrient that is frequently inaccessible to plants. Rice (Oryza sativa L.) plants employ the Combined Strategy for Fe uptake, which is composed by all features of Strategy II, common to all Poaceae species, and some features of Strategy I, common to non-Poaceae species. To understand the evolution of Fe uptake mechanisms, we analyzed the root transcriptomic response to Fe deficiency in O. sativa and its wild progenitor O. rufipogon. We identified 622 and 2,017 differentially expressed genes in O. sativa and O. rufipogon, respectively. Among the genes up-regulated in both species, we found Fe transporters associated with Strategy I, such as IRT1, IRT2 and NRAMP1; and genes associated with Strategy II, such as YSL15 and IRO2. In order to evaluate the conservation of these Strategies among other Poaceae, we identified the orthologs of these genes in nine species from the Oryza genus, maize and sorghum, and evaluated their expression profile in response to low Fe condition. Our results indicate that the Combined Strategy is not specific to O. sativa as previously proposed, but also present in species of the Oryza genus closely related to domesticated rice, and originated around the same time the AA genome lineage within Oryza diversified. Therefore, adaptation to Fe2+ acquisition via IRT1 in flooded soils precedes O. sativa domestication.

scholarly journals Insights into the chemistry of the amphibactin–metal (M3+) interaction and its role in antibiotic resistance

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Vidya Kaipanchery ◽  
Anamika Sharma ◽  
Fernando Albericio ◽  
Beatriz G. de la Torre
Keyword(s):  
Metal Ions ◽  
Iron Uptake ◽  
Pathogenic Bacteria ◽  
Iron Acquisition ◽  
Transition Metal Ions ◽  
Low Molecular Weight ◽  
Acquisition Strategies ◽  
Iron Deficient ◽  
Fe Uptake ◽  
Vibrio Genus

AbstractWe have studied the diversity and specificity of interactions of amphibactin produced by Vibrio genus bacterium (Vibrio sp. HC0601C5) with iron and various metal ions in + 3 oxidation state in an octahedral (Oh) environment. To survive in the iron-deficient environment of their host, pathogenic bacteria have devised various efficient iron acquisition strategies. One such strategy involves the production of low molecular weight peptides called siderophores, which have a strong affinity and specificity to chelate Fe3+ and can thus facilitate uptake of this metal in order to ensure iron requirements. The Fe uptake by amphibactin and the release of iron inside the cell have been studied. Comparison of the interaction of different transition metal ions (M3+) with amphibactin has been studied and it reveals that Co and Ga form stable complexes with this siderophore. The competition of Co and Ga with Fe impedes iron uptake by bacteria, thereby preventing infection.

scholarly journals Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic

2015 ◽  
Vol 12 (24) ◽  
pp. 7467-7482 ◽  
Author(s):  
C. R. Löscher ◽  
M. A. Fischer ◽  
S. C. Neulinger ◽  
B. Fiedler ◽  
M. Philippi ◽  
...  
Keyword(s):  
Microbial Community ◽  
Primary Production ◽  
Mixed Layer ◽  
North Atlantic ◽  
Primary Productivity ◽  
Open Ocean ◽  
Carbon Uptake ◽  
Biogeochemical Processes ◽  
Tropical North Atlantic ◽  
Uptake Rates

Abstract. The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open-ocean oxygen (O2) concentrations of approximately 40 μmol kg−1. The recent discovery of re-occurring mesoscale eddies with close to anoxic O2 concentrations (< 1 μmol kg−1) located just below the mixed layer has challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first microbial community study from a deoxygenated anticyclonic modewater eddy in the open waters of the ETNA. In the eddy, we observed significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the eddy indicated by elevated chlorophyll concentrations and carbon uptake rates of up to three times as high as in surrounding waters. Carbon uptake rates below the euphotic zone correlated to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our data indicate that high primary production in the eddy fuels export production and supports enhanced respiration in a specific microbial community at shallow depths, below the mixed-layer base. The transcription of the key functional marker gene for dentrification, nirS, further indicated a potential for nitrogen loss processes in O2-depleted core waters of the eddy. Dentrification is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies.

scholarly journals Picoplankton Community Composition by CARD-FISH and Flow Cytometric Techniques: A Preliminary Study in Central Adriatic Sea Water

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Anita Manti ◽  
Paola Boi ◽  
Federica Semprucci ◽  
Rosaria Cataudella ◽  
Stefano Papa
Keyword(s):  
Community Composition ◽  
Adriatic Sea ◽  
Heterotrophic Bacteria ◽  
Sea Water ◽  
Light Availability ◽  
Bacterial Biomass ◽  
Total Carbon ◽  
Autotrophic Picoplankton ◽  
Carbon Biomass ◽  
Card Fish

Data concerning picoplanktonic community composition and abundance in the Central Adriatic Sea are presented in an effort to improve the knowledge of bacterioplankton and autotrophic picoplankton and their seasonal changes. Flow cytometry analyses revealed the presence of two distinct bacteria populations: HNA and LNA cells. HNA cells showed an explicit correlation with viable and actively respiring cells. The study of viability and activity may increase our knowledge of the part that contributes really to the remineralization and bacterial biomass production. Authotrophic picoplankton abundance, especially picocyanobacteria, was strongly influenced by seasonality, indicating that light availability and water temperature are very important regulating factors. In terms of total carbon biomass, the main contribution came from heterotrophic bacteria with a lower contribution from autotrophic picoplankton. CARD-FISH evidenced, within the Eubacteria domain, the dominance of members of the phyla Alphaproteobacteria, with a strong contribution from SAR11clade, followed by Cytophaga-Flavobacterium and Gammaproteobacteria. The bacterial groups detected contributed differently depending when the sample was taken, suggesting possible seasonal patterns. This study documents for the first time picoplankton community composition in the Central Adriatic Sea using two different approaches, FCM and CARD-FISH, and could provide preliminary data for future studies.

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