scholarly journals Response of heterotrophic and autotrophic microbial plankton to inorganic and organic inputs along a latitudinal transect in the Atlantic Ocean

2010 ◽  
Vol 7 (5) ◽  
pp. 1701-1713 ◽  
Author(s):  
S. Martínez-García ◽  
E. Fernández ◽  
A. Calvo-Díaz ◽  
E. Marañón ◽  
X. A. G. Morán ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Bacterial Growth ◽  
Heterotrophic Bacteria ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Organic Nutrient ◽  
Plankton Biomass ◽  
Latitudinal Transect ◽  
Microbial Plankton

Abstract. The effects of inorganic and/or organic nutrient inputs on phytoplankton and heterotrophic bacteria have never been concurrently assessed in open ocean oligotrophic communities over a wide spatial gradient. We studied the effects of potentially limiting inorganic (nitrate, ammonium, phosphate, silica) and organic nutrient (glucose, aminoacids) inputs added separately as well as jointly, on microbial plankton biomass, community structure and metabolism in five microcosm experiments conducted along a latitudinal transect in the Atlantic Ocean (from 26° N to 29° S). Primary production rates increased up to 1.8-fold. Bacterial respiration and microbial community respiration increased up to 14.3 and 12.7-fold respectively. Bacterial production and bacterial growth efficiency increased up to 58.8-fold and 2.5-fold respectively. The largest increases were measured after mixed inorganic-organic nutrients additions. Changes in microbial plankton biomass were small as compared with those in metabolic rates. A north to south increase in the response of heterotrophic bacteria was observed, which could be related to a latitudinal gradient in phosphorus availability. Our results suggest that organic matter inputs will result in a predominantly heterotrophic versus autotrophic response and in increases in bacterial growth efficiency, particularly in the southern hemisphere. Subtle differences in the initial environmental and biological conditions are likely to result in differential microbial responses to inorganic and organic matter inputs.

scholarly journals Response of heterotrophic and autotrophic microbial plankton to inorganic and organic inputs along a latitudinal transect in the Atlantic Ocean

2010 ◽  
Vol 7 (1) ◽  
pp. 463-502
Author(s):  
S. Martínez-García ◽  
E. Fernández ◽  
A. Calvo-Díaz ◽  
E. Marañón ◽  
X. A. G. Morán ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Bacterial Growth ◽  
Heterotrophic Bacteria ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Organic Nutrient ◽  
Plankton Biomass ◽  
Latitudinal Transect ◽  
Microbial Plankton

Abstract. Atmospheric nutrient deposition into the open ocean increased over the past decades as a result of human activity and water-soluble organic nitrogen accounts for up to 30% of the total nitrogen inputs. The effects of inorganic and/or organic nutrient inputs on phytoplankton and heterotrophic bacteria have never been concurrently assessed in open ocean oligotrophic communities over a wide spatial gradient. We studied the effects of potentially limiting inorganic (nitrate, ammonium, phosphate, silica) and organic nutrient (glucose, aminoacids) inputs on microbial plankton biomass, community structure and metabolism in five microcosm experiments conducted along a latitudinal transect in the Atlantic Ocean (from 26° N to 29° S). Primary production rates increased up to 1.8-fold. Bacterial respiration and microbial community respiration increased up to 14.3 and 12.7-fold, respectively. Bacterial production and bacterial growth efficiency increased up to 58.8-fold and 2.5-fold, respectively. The largest increases were measured after mixed inorganic-organic nutrients additions. Changes in microbial plankton biomass were small as compared with those in metabolic rates. A north to south increase in the response of heterotrophic bacteria was observed, which could be related to a latitudinal gradient in phosphorus availability. Our results suggest that organic matter inputs associated with atmospheric deposition into the Atlantic Ocean will result in a predominantly heterotrophic versus autotrophic response and in increases in bacterial growth efficiency, particularly in the Southern Hemisphere. Subtle differences in the initial environmental and biological conditions are likely to result in differential microbial responses to inorganic and organic matter inputs.

scholarly journals Limitation of Bacterial Growth by Dissolved Organic Matter and Iron in the Southern Ocean

2000 ◽  
Vol 66 (2) ◽  
pp. 455-466 ◽  
Author(s):  
Matthew J. Church ◽  
David A. Hutchins ◽  
Hugh W. Ducklow
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Southern Ocean ◽  
Bacterial Growth ◽  
Bacterial Biomass ◽  
Biomass Accumulation ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Leucine Incorporation ◽  
Mean Cell Volume

ABSTRACT The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42°S and 55°S along 141°E. Bacterial abundance, mean cell volume, and [3H]thymidine and [3H]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial growth in the subtropical front, subantarctic zone, and subantarctic front responded most favorably to additions of dissolved free amino acids or glucose plus ammonium. Bacterial growth in these regions may be limited by input of both organic matter and reduced nitrogen. Unlike similar experimental results in other HNLC regions (subarctic and equatorial Pacific), growth stimulation of bacteria in the Southern Ocean resulted in significant biomass accumulation, apparently by stimulating bacterial growth in excess of removal processes. Bacterial growth was relatively unchanged by additions of iron alone; however, additions of glucose plus iron resulted in substantial increases in rates of bacterial growth and biomass accumulation. These results imply that bacterial growth efficiency and nitrogen utilization may be partly constrained by iron availability in the HNLC Southern Ocean.

scholarly journals Potential bioavailability of organic matter from atmospheric particles to marine heterotrophic bacteria

2020 ◽  
Vol 17 (24) ◽  
pp. 6271-6285
Author(s):  
Kahina Djaoudi ◽  
France Van Wambeke ◽  
Aude Barani ◽  
Nagib Bhairy ◽  
Servanne Chevaillier ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Incubation Period ◽  
Bacterial Growth ◽  
Heterotrophic Bacteria ◽  
Water Soluble ◽  
Bacterial Growth Efficiency ◽  
Anthropogenic Aerosols ◽  
Biogeochemical Models ◽  
Marine Heterotrophic Bacteria

Abstract. The surface ocean receives important amounts of organic carbon from atmospheric deposition. The degree of bioavailability of this source of organic carbon will determine its impact on the marine carbon cycle. In this study, the potential availability of dissolved organic carbon (DOC) leached from both desert dust and anthropogenic aerosols to marine heterotrophic bacteria was investigated. The experimental design was based on 16 d incubations, in the dark, of a marine bacterial inoculum into artificial seawater amended with water-soluble Saharan dust (D treatment) and anthropogenic (A treatment) aerosols, so that the initial DOC concentration was similar between treatments. Glucose-amended (G) and non-amended (control) treatments were run in parallel. Over the incubation period, an increase in bacterial abundance (BA) and bacterial production (BP) was observed first in the G treatment, followed then by the D and finally A treatments, with bacterial growth rates significantly higher in the G and D treatments than the A treatment. Following this growth, maxima of BP reached were similar in the D (879 ± 64 ng C L−1 h−1; n=3) and G (648 ± 156 ng C L−1 h−1; n=3) treatments and were significantly higher than in the A treatment (124 ng C L−1 h−1; n=2). The DOC consumed over the incubation period was similar in the A (9 µM; n=2) and D (9 ± 2 µM; n=3) treatments and was significantly lower than in the G treatment (22 ± 3 µM; n=3). Nevertheless, the bacterial growth efficiency (BGE) in the D treatment (14.2 ± 5.5 %; n=3) compared well with the G treatment (7.6 ± 2 %; n=3), suggesting that the metabolic use of the labile DOC fraction in both conditions was energetically equivalent. In contrast, the BGE in the A treatment was lower (1.7 %; n=2), suggesting that most of the used labile DOC was catabolized. The results obtained in this study highlight the potential of aerosol organic matter to sustain the metabolism of marine heterotrophs and stress the need to include this external source of organic carbon in biogeochemical models for a better constraining of the carbon budget.

scholarly journals Experimental evidence of the potential bioavailability for marine heterotrophic bacteria of aerosols organic matter

2020 ◽  
Author(s):  
Kahina Djaoudi ◽  
France Van Wambeke ◽  
Aude Barani ◽  
Najib Bhairy ◽  
Servanne Chevaillier ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Incubation Period ◽  
Bacterial Growth ◽  
Heterotrophic Bacteria ◽  
Water Soluble ◽  
Bacterial Growth Efficiency ◽  
Anthropogenic Aerosols ◽  
Biogeochemical Models ◽  
Marine Heterotrophic Bacteria

Abstract. The surface ocean receives important amounts of organic carbon from atmospheric deposition. The degree of bioavailability of this source of organic carbon will determine its impact on the marine carbon cycle. In this study, the potential availability of dissolved organic carbon (DOC) leached from both desert dust and anthropogenic aerosols to marine heterotrophic bacteria was investigated. The experimental design was based on 16-days incubation, in the dark, of a marine bacterial inoculum into artificial seawater amended with water-soluble Saharan dust (D-treatment) and anthropogenic (A-treatment) aerosols, so that the initial DOC concentration leachate from aerosols is 36 µM C. Glucose-amended (G) and non-amended (control) treatments were run in parallel. Over the incubation period, an increase in bacterial abundance (BA) and bacterial production (BP) was observed first in the G-treatment, followed then by D and finally A treatments, with bacterial growth rates significantly higher in the G and D treatments than the A treatment. Following this growth, maxima of BP reached were similar in D (879 ± 64 ng C L−1 h−1; n = 3) and G (648 ± 156 ng C L−1 h−1; n = 3) treatments and were significantly higher than in A-treatment (124 ± 39 ng C L−1 h−1; n = 2). The DOC consumed over the incubation period was similar in A (9 ± 4 µM; n = 2) and D (9 ± 2 µM; n = 3) treatments and was significantly lower than that consumed in the G-treatment (22 ± 3 µM). Nevertheless, the bacterial growth efficiency (BGE) in the D treatment (14.2 ± 5.5 %; n = 3) compared well with the G treatment (7.6 ± 2 %; n = 3), suggesting that the metabolic use of the labile DOC fraction in both conditions was energetically equivalent. In contrast, the BGE in the A-treatment was lower (1.7 ± 0.1 %; n = 2), suggesting that the most part of used labile DOC was catabolized. The results obtained in this study highlight the potential of aerosol organic matter to sustain the metabolism of marine heterotrophs and stress the need to include this external source of organic carbon into biogeochemical models, for a better constraining of the carbon budget.

scholarly journals Heterotrophic Bacterial Growth Efficiency and Community Structure at Different Natural Organic Carbon Concentrations

2003 ◽  
Vol 69 (7) ◽  
pp. 3701-3709 ◽  
Author(s):  
Alexander Eiler ◽  
Silke Langenheder ◽  
Stefan Bertilsson ◽  
Lars J. Tranvik
Keyword(s):  
Growth Rate ◽  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Community Composition ◽  
Bacterial Growth ◽  
Bacterial Biomass ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Doc Concentration

ABSTRACT Batch cultures of aquatic bacteria and dissolved organic matter were used to examine the impact of carbon source concentration on bacterial growth, biomass, growth efficiency, and community composition. An aged concentrate of dissolved organic matter from a humic lake was diluted with organic compound-free artificial lake water to obtain concentrations of dissolved organic carbon (DOC) ranging from 0.04 to 2.53 mM. The bacterial biomass produced in the cultures increased linearly with the DOC concentration, indicating that bacterial biomass production was limited by the supply of carbon. The bacterial growth rate in the exponential growth phase exhibited a hyperbolic response to the DOC concentration, suggesting that the maximum growth rate was constrained by the substrate concentration at low DOC concentrations. Likewise, the bacterial growth efficiency calculated from the production of biomass and CO2 increased asymptotically from 0.4 to 10.4% with increasing DOC concentration. The compositions of the microbial communities that emerged in the cultures were assessed by separation of PCR-amplified 16S rRNA fragments by denaturing gradient gel electrophoresis. Nonmetric multidimensional scaling of the gel profiles showed that there was a gradual change in the community composition along the DOC gradient; members of the β subclass of the class Proteobacteria and members of the Cytophaga-Flavobacterium group were well represented at all concentrations, whereas members of the α subclass of the Proteobacteria were found exclusively at the lowest carbon concentration. The shift in community composition along the DOC gradient was similar to the patterns of growth efficiency and growth rate. The results suggest that the bacterial growth efficiencies, the rates of bacterial growth, and the compositions of bacterial communities are not constrained by substrate concentrations in most natural waters, with the possible exception of the most oligotrophic environments.

scholarly journals Heterotrophic bacterial production and metabolic balance during the VAHINE mesocosm experiment in the New Caledonia lagoon

2016 ◽  
Vol 13 (11) ◽  
pp. 3187-3202 ◽  
Author(s):  
France Van Wambeke ◽  
Ulrike Pfreundt ◽  
Aude Barani ◽  
Hugo Berthelot ◽  
Thierry Moutin ◽  
...  
Keyword(s):  
Primary Production ◽  
Bacterial Growth ◽  
N2 Fixation ◽  
Bacterial Production ◽  
Heterotrophic Bacteria ◽  
New Caledonia ◽  
Gross Primary Production ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Second Phase

Abstract. Studies investigating the fate of diazotrophs through the microbial food web are lacking, although N2 fixation can fuel up to 50 % of new production in some oligotrophic oceans. In particular, the role played by heterotrophic prokaryotes in this transfer is largely unknown. In the frame of the VAHINE (VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific) experiment, three replicate large-volume (∼ 50 m3) mesocosms were deployed for 23 days in the new Caledonia lagoon and were intentionally fertilized on day 4 with dissolved inorganic phosphorus (DIP) to stimulate N2 fixation. We specifically examined relationships between heterotrophic bacterial production (BP) and N2 fixation or primary production, determined bacterial growth efficiency and established carbon budgets. BP was statistically higher during the second phase of the experiment (P2: days 15–23), when chlorophyll biomass started to increase compared to the first phase (P1: days 5–14). Phosphatase alkaline activity increased drastically during the second phase of the experiment, showing adaptations of microbial populations after utilization of the added DIP. Notably, among autotrophs, Synechococcus abundances increased during P2, possibly related to its capacity to assimilate leucine and to produce alkaline phosphatase. Bacterial growth efficiency based on the carbon budget (27–43 %), was notably higher than generally cited for oligotrophic environments and discussed in links with the presence of abundant species of bacteria expressing proteorhodopsin. The main fates of gross primary production (particulate + dissolved) were respiration (67 %) and export through sedimentation (17 %). BP was highly correlated with particulate primary production and chlorophyll biomass during both phases of the experiment but was slightly correlated, and only during P2 phase, with N2 fixation rates. Heterotrophic bacterial production was strongly stimulated after mineral N enrichment experiments, suggesting N-limitation of heterotrophic bacteria across the experiment. N2 fixation rates corresponded to 17–37 % of the nitrogen demand of heterotrophic bacteria. Our results suggest that most of the diazotroph-derived nitrogen fuelled the heterotrophic bacterial community through indirect processes generating dissolved organic matter and detritus, like mortality, lysis and grazing of both diazotrophs and non-diazotrophs.

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