scholarly journals Effect of Ocean Acidification on Bacterial Metabolic Activity and Community Composition in Oligotrophic Oceans, Inferred From Short-Term Bioassays

2021 ◽  
Vol 12 ◽  
Author(s):  
Caiqin Hu ◽  
Xiangfu Li ◽  
Maoqiu He ◽  
Peng Jiang ◽  
Aimin Long ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Ocean Acidification ◽  
Carbon Cycling ◽  
Community Composition ◽  
Metabolic Activity ◽  
Bacterial Production ◽  
Bacterial Growth Efficiency ◽  
Nucleic Acid Content ◽  
Bacterial Respiration ◽  
Short Term

Increasing anthropogenic CO2 emissions in recent decades cause ocean acidification (OA), affecting carbon cycling in oceans by regulating eco-physiological processes of plankton. Heterotrophic bacteria play an important role in carbon cycling in oceans. However, the effect of OA on bacteria in oceans, especially in oligotrophic regions, was not well understood. In our study, the response of bacterial metabolic activity and community composition to OA was assessed by determining bacterial production, respiration, and community composition at the low-pCO2 (400 ppm) and high-pCO2 (800 ppm) treatments over the short term at two oligotrophic stations in the northern South China Sea. Bacterial production decreased significantly by 17.1–37.1 % in response to OA, since bacteria with high nucleic acid content preferentially were repressed by OA, which was less abundant under high-pCO2 treatment. Correspondingly, shifts in bacterial community composition occurred in response to OA, with a high fraction of the small-sized bacteria and high bacterial species diversity in a high-pCO2 scenario at K11. Bacterial respiration responded to OA differently at both stations, most likely attributed to different physiological responses of the bacterial community to OA. OA mitigated bacterial growth efficiency, and consequently, a larger fraction of DOC entering microbial loops was transferred to CO2.

scholarly journals Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Kasia Piwosz ◽  
Ana Vrdoljak ◽  
Thijs Frenken ◽  
Juan Manuel González-Olalla ◽  
Danijela Šantić ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Light Intensity ◽  
Bacterial Community ◽  
Primary Production ◽  
Community Composition ◽  
Bacterial Production ◽  
Bacterial Community Composition ◽  
Bacterial Activity ◽  
Bacterial Respiration ◽  
Metabolic Coupling

ABSTRACT Phytoplankton is a key component of aquatic microbial communities, and metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon (DOC). Yet, the impact of primary production on bacterial activity and community composition remains largely unknown, as, for example, in the case of aerobic anoxygenic phototrophic (AAP) bacteria that utilize both phytoplankton-derived DOC and light as energy sources. Here, we studied how reduction of primary production in a natural freshwater community affects the bacterial community composition and its activity, focusing primarily on AAP bacteria. The bacterial respiration rate was the lowest when photosynthesis was reduced by direct inhibition of photosystem II and the highest in ambient light condition with no photosynthesis inhibition, suggesting that it was limited by carbon availability. However, bacterial assimilation rates of leucine and glucose were unaffected, indicating that increased bacterial growth efficiency (e.g., due to photoheterotrophy) can help to maintain overall bacterial production when low primary production limits DOC availability. Bacterial community composition was tightly linked to light intensity, mainly due to the increased relative abundance of light-dependent AAP bacteria. This notion shows that changes in bacterial community composition are not necessarily reflected by changes in bacterial production or growth and vice versa. Moreover, we demonstrated for the first time that light can directly affect bacterial community composition, a topic which has been neglected in studies of phytoplankton-bacteria interactions. IMPORTANCE Metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon in aquatic environments, and yet how changes in the rate of primary production affect the bacterial activity and community composition remains understudied. Here, we experimentally limited the rate of primary production either by lowering light intensity or by adding a photosynthesis inhibitor. The induced decrease had a greater influence on bacterial respiration than on bacterial production and growth rate, especially at an optimal light intensity. This suggests that changes in primary production drive bacterial activity, but the effect on carbon flow may be mitigated by increased bacterial growth efficiencies, especially of light-dependent AAP bacteria. Bacterial activities were independent of changes in bacterial community composition, which were driven by light availability and AAP bacteria. This direct effect of light on composition of bacterial communities has not been documented previously.

scholarly journals Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

2018 ◽  
Vol 21 (1) ◽  
pp. 34-49 ◽  
Author(s):  
Olesya V. Kolmakova ◽  
Michail I. Gladyshev ◽  
Jérémy André Fonvielle ◽  
Lars Ganzert ◽  
Thomas Hornick ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Carbon Cycling ◽  
Community Composition ◽  
Bacterial Community Composition

Cow responses and evolution of the rumen bacterial and methanogen community following a complete rumen content transfer

2018 ◽  
Vol 156 (8) ◽  
pp. 1047-1058
Author(s):  
T. De Mulder ◽  
L. Vandaele ◽  
N. Peiren ◽  
A. Haegeman ◽  
T. Ruttink ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Community Composition ◽  
Rumen Content ◽  
Short Term ◽  
Microbiome Composition ◽  
Nutritional Conditions ◽  
Microbiome Diversity ◽  
Methanogen Community ◽  
New Community

AbstractUnderstanding the rumen microbial ecosystem requires the identification of factors that influence the community structure, such as nutrition, physiological condition of the host and host–microbiome interactions. The objective of the current study was to describe the rumen microbial communities before, during and after a complete rumen content transfer. The rumen contents of one donor cow were removed completely and used as inoculum for the emptied rumen of the donor itself and three acceptor cows under identical physiological and nutritional conditions. Temporal changes in microbiome composition and rumen function were analysed for each of four cows over a period of 6 weeks. Shortly after transfer, the cows showed different responses to perturbation of their rumen content. Feed intake depression in the first 2 weeks after transfer resulted in short-term changes in milk production, methane emission, fatty acid composition and rumen bacterial community composition. These effects were more pronounced in two cows, whose microbiome composition showed reduced diversity. The fermentation metrics and microbiome diversity of the other two cows were not affected. Their rumen bacterial community initially resembled the composition of the donor but evolved to a new community profile that resembled neither the donor nor their original composition. Descriptive data presented in the current paper show that the rumen bacterial community composition can quickly recover from a reduction in microbiome diversity after a severe perturbation. In contrast to the bacteria, methanogenic communities were more stable over time and unaffected by stress or host effects.

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 Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

2015 ◽  
Vol 81 (23) ◽  
pp. 8224-8232 ◽  
Author(s):  
Eva Teira ◽  
Víctor Hernando-Morales ◽  
Francisco M. Cornejo-Castillo ◽  
Laura Alonso-Sáez ◽  
Hugo Sarmento ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Community Composition ◽  
Nucleic Acid Content ◽  
Carbon Conversion ◽  
Production Rates ◽  
Conversion Factors ◽  
Content Type ◽  
Carbon Production ◽  
The Impact

ABSTRACTThe transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu−1and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyllaconcentration, picocyanobacterial abundance (mostlyProchlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that bothProchlorococcusand HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean.

scholarly journals Interaction between resource identity and bacterial community composition regulates bacterial respiration in aquatic ecosystems

2015 ◽  
Vol 75 (4 suppl 1) ◽  
pp. 150-157
Author(s):  
A. P. F. Pires ◽  
A. Caliman ◽  
T. Laque ◽  
F. A. Esteves ◽  
V. F. Farjalla
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Functional Diversity ◽  
Aquatic Ecosystems ◽  
Aquatic Macrophyte ◽  
Bacterial Community Composition ◽  
Bacterial Respiration ◽  
Bacterial Populations ◽  
Linear Pattern ◽  
Composition Structure

Abstract Resource identity and composition structure bacterial community, which in turn determines the magnitude of bacterial processes and ecological services. However, the complex interaction between resource identity and bacterial community composition (BCC) has been poorly understood so far. Using aquatic microcosms, we tested whether and how resource identity interacts with BCC in regulating bacterial respiration and bacterial functional diversity. Different aquatic macrophyte leachates were used as different carbon resources while BCC was manipulated through successional changes of bacterial populations in batch cultures. We observed that the same BCC treatment respired differently on each carbon resource; these resources also supported different amounts of bacterial functional diversity. There was no clear linear pattern of bacterial respiration in relation to time succession of bacterial communities in all leachates, i.e. differences on bacterial respiration between different BCC were rather idiosyncratic. Resource identity regulated the magnitude of respiration of each BCC, e.g. Ultricularia foliosa leachate sustained the greatest bacterial functional diversity and lowest rates of bacterial respiration in all BCC. We conclude that both resource identity and the BCC interact affecting the pattern and the magnitude of bacterial respiration in aquatic ecosystems.

Assessment of Bacterial Community Composition of Anaerobic Granular Sludge in Response to Short-Term Uranium Exposure

2018 ◽  
Vol 76 (3) ◽  
pp. 648-659 ◽  
Author(s):  
Taotao Zeng ◽  
Shiqi Zhang ◽  
Xiang Gao ◽  
Guohua Wang ◽  
Piet N. L. Lens ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Community Composition ◽  
Granular Sludge ◽  
Anaerobic Granular Sludge ◽  
Short Term

scholarly journals Effect of CO<sub>2</sub> enrichment on bacterial metabolism in an Arctic fjord

2013 ◽  
Vol 10 (5) ◽  
pp. 3285-3296 ◽  
Author(s):  
C. Motegi ◽  
T. Tanaka ◽  
J. Piontek ◽  
C. P. D. Brussaard ◽  
J.-P. Gattuso ◽  
...  
Keyword(s):  
Growth Rate ◽  
Carbon Metabolism ◽  
Bacterial Production ◽  
Nutrient Addition ◽  
Bacterial Growth Efficiency ◽  
Temporary Increase ◽  
Bacterial Respiration ◽  
Carbon Demand ◽  
Wide Range ◽  
The Impact

Abstract. The anthropogenic increase of carbon dioxide (CO2) alters the seawater carbonate chemistry, with a decline of pH and an increase in the partial pressure of CO2 (pCO2). Although bacteria play a major role in carbon cycling, little is known about the impact of rising pCO2 on bacterial carbon metabolism, especially for natural bacterial communities. In this study, we investigated the effect of rising pCO2 on bacterial production (BP), bacterial respiration (BR) and bacterial carbon metabolism during a mesocosm experiment performed in Kongsfjorden (Svalbard) in 2010. Nine mesocosms with pCO2 levels ranging from ca. 180 to 1400 μatm were deployed in the fjord and monitored for 30 days. Generally BP gradually decreased in all mesocosms in an initial phase, showed a large (3.6-fold average) but temporary increase on day 10, and increased slightly after inorganic nutrient addition. Over the wide range of pCO2 investigated, the patterns in BP and growth rate of bulk and free-living communities were generally similar over time. However, BP of the bulk community significantly decreased with increasing pCO2 after nutrient addition (day 14). In addition, increasing pCO2 enhanced the leucine to thymidine (Leu : TdR) ratio at the end of experiment, suggesting that pCO2 may alter the growth balance of bacteria. Stepwise multiple regression analysis suggests that multiple factors, including pCO2, explained the changes of BP, growth rate and Leu : TdR ratio at the end of the experiment. In contrast to BP, no clear trend and effect of changes of pCO2 was observed for BR, bacterial carbon demand and bacterial growth efficiency. Overall, the results suggest that changes in pCO2 potentially influence bacterial production, growth rate and growth balance rather than the conversion of dissolved organic matter into CO2.

scholarly journals Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition

2014 ◽  
Vol 11 (6) ◽  
pp. 1479-1489 ◽  
Author(s):  
K. Attermeyer ◽  
T. Hornick ◽  
Z. E. Kayler ◽  
A. Bahr ◽  
E. Zwirnmann ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Temporal Dynamics ◽  
Heterotrophic Bacteria ◽  
Bacterial Community Composition ◽  
Bacterial Biomass ◽  
Trophic Levels ◽  
Bacterial Growth Efficiency ◽  
Chemical Quality ◽  
Bacterial C

Abstract. Dissolved organic carbon (DOC) concentrations – mainly of terrestrial origin – are increasing worldwide in inland waters. Heterotrophic bacteria are the main consumers of DOC and thus determine DOC temporal dynamics and availability for higher trophic levels. Our aim was to study bacterial carbon (C) turnover with respect to DOC quantity and chemical quality using both allochthonous and autochthonous DOC sources. We incubated a natural bacterial community with allochthonous C (13C-labeled beech leachate) and increased concentrations and pulses (intermittent occurrence of organic matter input) of autochthonous C (phytoplankton lysate). We then determined bacterial C consumption, activities, and community composition together with the C flow through bacteria using stable C isotopes. The chemical analysis of single sources revealed differences in aromaticity and low- and high-molecular-weight substance fractions (LMWS and HMWS, respectively) between allochthonous and autochthonous C sources. Both DOC sources (allochthonous and autochthonous DOC) were metabolized at a high bacterial growth efficiency (BGE) around 50%. In treatments with mixed sources, rising concentrations of added autochthonous DOC resulted in a further, significant increase in bacterial DOC consumption of up to 68% when nutrients were not limiting. This rise was accompanied by a decrease in the humic substance (HS) fraction and an increase in bacterial biomass. Changes in DOC concentration and consumption in mixed treatments did not affect bacterial community composition (BCC), but BCC differed in single vs. mixed incubations. Our study highlights that DOC quantity affects bacterial C consumption but not BCC in nutrient-rich aquatic systems. BCC shifted when a mixture of allochthonous and autochthonous C was provided simultaneously to the bacterial community. Our results indicate that chemical quality rather than source of DOC per se (allochthonous vs. autochthonous) determines bacterial DOC turnover.

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