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

2015 ◽  
Vol 12 (23) ◽  
pp. 19861-19900 ◽  
Author(s):  
F. Van Wambeke ◽  
U. Pfreundt ◽  
A. Barani ◽  
H. Berthelot ◽  
T. Moutin ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Primary Production ◽  
Bacterial Growth ◽  
N2 Fixation ◽  
Bacterial Production ◽  
Carbon Budget ◽  
New Caledonia ◽  
Growth Efficiency ◽  
Mesocosm Experiment ◽  
Bacterial Growth Efficiency

Abstract. N2 fixation fuels ~ 50 % of new primary production in the oligotrophic South Pacific Ocean. The VAHINE mesocosm experiment designed to track the fate of diazotroph derived nitrogen (DDN) in the New Caledonia lagoon. Here, we examined the temporal dynamics of heterotrophic bacterial production during this experiment. Three replicate large-volume (~ 50 m3) mesocosms were deployed and were intentionally fertilized with dissolved inorganic phosphorus (DIP) to stimulate N2 fixation. We specifically examined relationships between N2 fixation rates and primary production, determined bacterial growth efficiency and established carbon budgets of the system from the DIP fertilization to the end of the experiment (days 5–23). Heterotrophic bacterioplankton production (BP) and alkaline phosphatase activity (APA) were 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). 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 was notably higher than generally cited for oligotrophic environments (27–43 %), possibly due to a high representation of proteorhodopsin-containing organisms within the picoplanctonic community. The carbon budget showed that the main fate of gross primary production (particulate + dissolved) was 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 slightly correlated, and only during P2 phase, with N2 fixation rates. Our results suggest that most of the DDN reached the heterotrophic bacterial community through indirect processes, like mortality, lysis and grazing.

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.

scholarly journals Dynamics and controls of heterotrophic prokaryotic production in the western tropical South Pacific Ocean: links with diazotrophic and photosynthetic activity

2018 ◽  
Vol 15 (9) ◽  
pp. 2669-2689 ◽  
Author(s):  
France Van Wambeke ◽  
Audrey Gimenez ◽  
Solange Duhamel ◽  
Cécile Dupouy ◽  
Dominique Lefevre ◽  
...  
Keyword(s):  
Primary Production ◽  
Bacterial Growth ◽  
N2 Fixation ◽  
Euphotic Zone ◽  
South Pacific ◽  
Growth Efficiency ◽  
Subtropical Gyre ◽  
Bacterial Growth Efficiency ◽  
Spatial And Temporal Variability ◽  
Production Ratio

Abstract. Heterotrophic prokaryotic production (BP) was studied in the western tropical South Pacific (WTSP) using the leucine technique, revealing spatial and temporal variability within the region. Integrated over the euphotic zone, BP ranged from 58 to 120 mg C m−2 d−1 within the Melanesian Archipelago, and from 31 to 50 mg C m−2 d−1 within the western subtropical gyre. The collapse of a bloom was followed during 6 days in the south of Vanuatu using a Lagrangian sampling strategy. During this period, rapid evolution was observed in the three main parameters influencing the metabolic state: BP, primary production (PP) and bacterial growth efficiency. With N2 fixation being one of the most important fluxes fueling new production, we explored relationships between BP, PP and N2 fixation rates over the WTSP. The contribution of N2 fixation rates to bacterial nitrogen demand ranged from 3 to 81 %. BP variability was better explained by the variability of N2 fixation rates than by that of PP in surface waters of the Melanesian Archipelago, which were characterized by N-depleted layers and low DIP turnover times (TDIP < 100 h). This is consistent with the fact that nitrogen was often one of the main factors controlling BP on short timescales, as shown using enrichment experiments, followed by dissolved inorganic phosphate (DIP) near the surface and labile organic carbon deeper in the euphotic zone. However, BP was more significantly correlated with PP, but not with N2 fixation rates where DIP was more available (TDIP > 100 h), deeper in the Melanesian Archipelago, or within the entire euphotic zone in the subtropical gyre. The bacterial carbon demand to gross primary production ratio ranged from 0.75 to 3.1. These values are discussed in the framework of various assumptions and conversion factors used to estimate this ratio, including the methodological errors, the daily variability of BP, the bacterial growth efficiency and one bias so far not considered: the ability for Prochlorococcus to assimilate leucine in the dark.

scholarly journals Temporal Variation of Bacterial Respiration and Growth Efficiency in Tropical Coastal Waters

2009 ◽  
Vol 75 (24) ◽  
pp. 7594-7601 ◽  
Author(s):  
Choon Weng Lee ◽  
Chui Wei Bong ◽  
Yii Siang Hii
Keyword(s):  
Temporal Variation ◽  
Bacterial Growth ◽  
Coastal Waters ◽  
Bacterial Production ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Bacterial Respiration ◽  
Substrate Quality ◽  
Carbon Demand ◽  
Net Heterotrophy

ABSTRACT We investigated the temporal variation of bacterial production, respiration, and growth efficiency in the tropical coastal waters of Peninsular Malaysia. We selected five stations including two estuaries and three coastal water stations. The temperature was relatively stable (averaging around 29.5°C), whereas salinity was more variable in the estuaries. We also measured dissolved organic carbon and nitrogen (DOC and DON, respectively) concentrations. DOC generally ranged from 100 to 900 μM, whereas DON ranged from 0 to 32 μM. Bacterial respiration ranged from 0.5 to 3.2 μM O2 h−1, whereas bacterial production ranged from 0.05 to 0.51 μM C h−1. Bacterial growth efficiency was calculated as bacterial production/(bacterial production + respiration), and ranged from 0.02 to 0.40. Multiple correlation analyses revealed that bacterial production was dependent upon primary production (r2 = 0.169, df = 31, and P < 0.02) whereas bacterial respiration was dependent upon both substrate quality (i.e., DOC/DON ratio) (r2 = 0.137, df = 32, and P = 0.03) and temperature (r2 = 0.113, df = 36, and P = 0.04). Substrate quality was the most important factor (r2 = 0.119, df = 33, and P = 0.04) for the regulation of bacterial growth efficiency. Using bacterial growth efficiency values, the average bacterial carbon demand calculated was from 5.30 to 11.28 μM C h−1. When the bacterial carbon demand was compared with primary productivity, we found that net heterotrophy was established at only two stations. The ratio of bacterial carbon demand to net primary production correlated significantly with bacterial growth efficiency (r2 = 0.341, df = 35, and P < 0.001). From nonlinear regression analysis, we found that net heterotrophy was established when bacterial growth efficiency was <0.08. Our study showed the extent of net heterotrophy in these waters and illustrated the importance of heterotrophic microbial processes in coastal aquatic food webs.

scholarly journals Dynamics of N<sub>2</sub> fixation and fate of diazotroph-derived nitrogen in a low nutrient low chlorophyll ecosystem: results from the VAHINE mesocosm experiment (New Caledonia)

2015 ◽  
Vol 12 (23) ◽  
pp. 19579-19626 ◽  
Author(s):  
S. Bonnet ◽  
H. Berthelot ◽  
K. Turk-Kubo ◽  
S. Fawcett ◽  
E. Rahav ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Particulate Organic Carbon ◽  
N2 Fixation ◽  
Bacterial Production ◽  
New Caledonia ◽  
Seawater Temperature ◽  
Global Ocean ◽  
Nitrogen And Phosphorus ◽  
Standing Stocks

Abstract. N2 fixation rates were measured daily in large (~ 50 m3) mesocosms deployed in the tropical South West Pacific coastal ocean (New Caledonia) to investigate the spatial and temporal dynamics of diazotrophy and the fate of diazotroph-derived nitrogen (DDN) in a low nutrient, low chlorophyll ecosystem. The mesocosms were intentionally fertilized with ~ 0.8 μM dissolved inorganic phosphorus (DIP) to stimulate diazotrophy. Bulk N2 fixation rates were replicable between the three mesocosms, averaged 18.5 ± 1.1 nmol N L−1 d−1 over the 23 days, and increased by a factor of two during the second half of the experiment (days 15 to 23) to reach 27.3 ± 1.0 nmol N L−1 d−1. These rates are higher than the upper range reported for the global ocean, indicating that the waters surrounding New Caledonia are particularly favourable for N2 fixation. During the 23 days of the experiment, N2 fixation rates were positively correlated with seawater temperature, primary production, bacterial production, standing stocks of particulate organic carbon, nitrogen and phosphorus, and alkaline phosphatase activity, and negatively correlated with DIP concentrations, DIP turnover time, nitrate, and dissolved organic nitrogen and phosphorus concentrations. The fate of DDN was investigated during the bloom of the unicellular diazotroph, UCYN-C, that occurred during the second half of the experiment. Quantification of diazotrophs in the sediment traps indicates that ~ 10 % of UCYN-C from the water column were exported daily to the traps, representing as much as 22.4 ± 5.5 % of the total POC exported at the height of the UCYN-C bloom. This export was mainly due to the aggregation of small (5.7 ± 0.8 μm) UCYN-C cells into large (100–500 μm) aggregates. During the same time period, a DDN transfer experiment based on high-resolution nanometer scale secondary ion mass spectrometry (nanoSIMS) coupled with 15N2 isotopic labelling revealed that 16 ± 6 % of the DDN was released to the dissolved pool and 21 ± 4 % was transferred to non-diazotrophic plankton, mainly picoplankton (18 ± 4 %) followed by diatoms (3 ± 2 %) within 24 h of incubation. This is consistent with the observed dramatic increase in picoplankton and diatom abundances, primary production, bacterial production and standing stocks of particulate organic carbon, nitrogen and phosphorus during the second half of the experiment in the mesocosms. These results offer insights into the fate of DDN during a bloom of UCYN-C in low nutrient, low chlorophyll ecosystems.

scholarly journals Effect of CO<sub>2</sub> enrichment on bacterial production and respiration and on bacterial carbon metabolism in Arctic waters

2012 ◽  
Vol 9 (10) ◽  
pp. 15213-15235 ◽  
Author(s):  
C. Motegi ◽  
T. Tanaka ◽  
J. Piontek ◽  
C. P. D. Brussaard ◽  
J. P. Gattuso ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Bacterial Production ◽  
Growth Efficiency ◽  
Mesocosm Experiment ◽  
Bacterial Growth Efficiency ◽  
Temporary Increase ◽  
Bacterial Respiration ◽  
Clear Trend ◽  
Carbon Demand ◽  
The Impact

Abstract. The impact of rising carbon dioxide (pCO2) on bacterial production (BP), bacterial respiration (BR) and bacterial carbon metabolism was investigated during the mesocosm experiment in Kongsfjord (Svalbard) in 2010. The mesocosm experiment lasted 30 days and nine mesocosms with pCO2 levels ranging from ca. 180 to 1400 μatm were used. Generally, BP gradually decreased in all mesocosms in an initial phase, showed a large (3.6-fold in average) but temporary increase on day 10, and increased slightly afterwards. BP increased with increasing pCO2 at the beginning of the experiment (day 5). This trend became inversed and BP decreased with increasing pCO2 on day 14 (after nutrient addition). Interestingly, increasing pCO2 enhanced the leucine and thymidine ratio at the end of experiment, suggesting that pCO2 may alter the growth balance of bacteria. In contrast to BP, no clear trend and effect of changes of pCO2 was observed for BR, bacterial carbon demand and bacterial growth efficiency. Our results suggest that (1) the response to elevated pCO2 had a strong temporal variation, potentially linked to the nutrient status, and (2) pCO2 had an influence on biomass accumulation (i.e. BP) rather than on the conversion of dissolved organic matter into CO2 (i.e. BR).

scholarly journals Dynamics of N<sub>2</sub> fixation and fate of diazotroph-derived nitrogen in a low-nutrient, low-chlorophyll ecosystem: results from the VAHINE mesocosm experiment (New Caledonia)

2016 ◽  
Vol 13 (9) ◽  
pp. 2653-2673 ◽  
Author(s):  
Sophie Bonnet ◽  
Hugo Berthelot ◽  
Kendra Turk-Kubo ◽  
Sarah Fawcett ◽  
Eyal Rahav ◽  
...  
Keyword(s):  
Primary Production ◽  
N2 Fixation ◽  
Bacterial Production ◽  
New Caledonia ◽  
Seawater Temperature ◽  
Sediment Traps ◽  
Turnover Time ◽  
Global Ocean ◽  
Nitrogen And Phosphorus ◽  
Standing Stocks

Abstract. N2 fixation rates were measured daily in large (∼ 50 m3) mesocosms deployed in the tropical southwest Pacific coastal ocean (New Caledonia) to investigate the temporal variability in N2 fixation rates in relation with environmental parameters and study the fate of diazotroph-derived nitrogen (DDN) in a low-nutrient, low-chlorophyll ecosystem. The mesocosms were fertilized with  ∼ 0.8 µM dissolved inorganic phosphorus (DIP) to stimulate diazotrophy. Bulk N2 fixation rates were replicable between the three mesocosms, averaged 18.5 ± 1.1 nmol N L−1 d−1 over the 23 days, and increased by a factor of 2 during the second half of the experiment (days 15 to 23) to reach 27.3 ± 1.0 nmol N L−1 d−1. These later rates measured after the DIP fertilization are higher than the upper range reported for the global ocean. During the 23 days of the experiment, N2 fixation rates were positively correlated with seawater temperature, primary production, bacterial production, standing stocks of particulate organic carbon (POC), nitrogen (PON) and phosphorus (POP), and alkaline phosphatase activity, and negatively correlated with DIP concentrations, DIP turnover time, nitrate, and dissolved organic nitrogen and phosphorus concentrations. The fate of DDN was investigated during a bloom of the unicellular diazotroph UCYN-C that occurred during the second half of the experiment. Quantification of diazotrophs in the sediment traps indicates that ∼ 10 % of UCYN-C from the water column was exported daily to the traps, representing as much as 22.4 ± 5.5 % of the total POC exported at the height of the UCYN-C bloom. This export was mainly due to the aggregation of small (5.7 ± 0.8 µm) UCYN-C cells into large (100–500 µm) aggregates. During the same time period, a DDN transfer experiment based on high-resolution nanometer-scale secondary ion mass spectrometry (nanoSIMS) coupled with 15N2 isotopic labeling revealed that 16 ± 6 % of the DDN was released to the dissolved pool and 21 ± 4 % was transferred to non-diazotrophic plankton, mainly picoplankton (18 ± 4 %) followed by diatoms (3 ± 2 %). This is consistent with the observed dramatic increase in picoplankton and diatom abundances, primary production, bacterial production, and standing stocks of POC, PON, and POP in the mesocosms during the second half of the experiment. These results offer insights into the fate of DDN during a bloom of UCYN-C in low-nutrient, low-chlorophyll ecosystems.

The effect of energy and nitrogen supply pattern on rumen bacterial growthin vitro

1991 ◽  
Vol 53 (2) ◽  
pp. 165-175 ◽  
Author(s):  
P. H. Henning ◽  
D. G. Steyn ◽  
H. H. Meissner
Keyword(s):  
Bacterial Growth ◽  
Specific Growth ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Batch Cultures ◽  
Time Zero ◽  
N Supply ◽  
Pulse Dose ◽  
Supply Pattern ◽  
Glucose Supply

AbstractThe effect of energy and nitrogen (N) supply pattern on rumen bacterial growth was investigated in vitro. In experiment 1, glucose was was fed to batch cultures of mixed rumen bacteria according to three patterns namely a pulse dose at time zero (P); even increments at 0·5-h intervals (G) or an intermediate pattern (I), whilst N was supplied in excess. In experiment 2, glucose and N (not in excess) were fed to batch cultures according to four patterns namely glucose and N as pulse doses at time zero, (EPNP); glucose as a pulse dose at time zero and N in 24 even increments at 0·5-h intervals (EPNG); glucose in 24 even increments at 0·5-h intervals and N as a pulse dose at time zero (EGNP) or both glucose and N in 24 even increments at 0·5-h intervals (EGNG). Fermentaton was studied over a 12-h period for both experiments.In experiment 1, bacterial growth efficiency and specific growth rate (39·8,35·5 and 29·9 (g bacterial dry matter (DM) per mol glucose utilized) and 0·33, 0·27 and 0·20 (fraction per h) for treatments P, I, and G respectively) differed significantly between glucose supply patterns. In experiment 2, bacterial growth efficiency and specific growth rate (33·8, 34·7, 25·9 and 22·5 (g baterial DM per mol glucose) and 0·21, 0·18, 0·14 and 0·13 (fraction per h) for treatments EPNP, EPNG, EGNP and EGNG respectively) differed significantly only between glucose supply patterns.It is concluded that the pattern according to which a given amount of energy becomes available affects bacterial growth efficiency, with the fastest supply rate giving the highest efficiency and that, within accepted levels of N supply, synchronization between energy and N availability may be of less importance to bacterial growth efficiency than the energy supply pattern.

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