In Situ Chemotaxis Assay to Examine Microbial Behavior in Aquatic Ecosystems

10.3791/61062 ◽  
2020 ◽  
Author(s):  
Estelle E. Clerc ◽  
Jean-Baptiste Raina ◽  
Bennett S. Lambert ◽  
Justin Seymour ◽  
Roman Stocker
Keyword(s):  
Aquatic Ecosystems ◽  
Chemotaxis Assay

scholarly journals Microbial Processing and Production of Aquatic Fluorescent Organic Matter in a Model Freshwater System

Water ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 10
Author(s):  
Bethany Fox ◽  
Robin Thorn ◽  
Alexandre Anesio ◽  
Timothy Cox ◽  
John Attridge ◽  
...  
Keyword(s):  
Organic Matter ◽  
Aquatic Ecosystems ◽  
Sampling Period ◽  
Cell Multiplication ◽  
Cellular Processes ◽  
Bacterial Enumeration ◽  
Freshwater System ◽  
Parallel Factor ◽  
Incubation Temperatures

Organic matter (OM) has an essential biogeochemical influence along the hydrological continuum and within aquatic ecosystems. Organic matter derived via microbial processes was investigated within a range of model freshwater samples over a 10-day period. For this, excitation-emission matrix (EEM) fluorescence spectroscopy in combination with parallel factor (PARAFAC) analysis was employed. This research shows the origin and processing of both protein-like and humic-like fluorescence within environmental and synthetic samples over the sampling period. The microbial origin of Peak T fluorescence is demonstrated within both synthetic samples and in environmental samples. Using a range of incubation temperatures provides evidence for the microbial metabolic origin of Peak T fluorescence. From temporally resolved experiments, evidence is provided that Peak T fluorescence is an indication of metabolic activity at the microbial community level and not a proxy for bacterial enumeration. This data also reveals that humic-like fluorescence can be microbially derived in situ and is not solely of terrestrial origin, likely to result from the upregulation of cellular processes prior to cell multiplication. This work provides evidence that freshwater microbes can engineer fluorescent OM, demonstrating that microbial communities not only process, but also transform, fluorescent organic matter.

scholarly journals Effectiveness Assessment of a New System of Sediment Trap in the Investigation of Matter Sedimentation in a Reservoir—A Case Study

Hydrology ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 48 ◽  
Author(s):  
Maksymilian Cieśla ◽  
Lilianna Bartoszek ◽  
Renata Gruca-Rokosz
Keyword(s):  
Aquatic Ecosystems ◽  
Research Work ◽  
Sediment Traps ◽  
Stable Operation ◽  
Dual Chamber ◽  
Innovative Design ◽  
Water Ecosystems ◽  
Effectiveness Assessment

This paper presents results of the research on the effectiveness of entrapping sediment matter in newly designed sediment traps. Four traps, characterized by different geometrical and construction parameters, were analyzed. The assessment of the operation of the traps was made on the basis of research work conducted in situ in a small retention reservoir located in Blizne, south-east Poland during summer 2017 and 2018. Under environmental conditions present during the research, trap number 2 emerged as the most effective. It was characterized by a height to diameter ratio equal to 6.06, as well as innovative design thanks to the presence of a dual-chamber cylindrical vessel with a sedimentation funnel ending in a deflector. The proposed construction solution ensured optimal, stable operation of the trap. This trap is more effective in entrapping sediment matter than the simple tools described in the literature so far. In addition, it can be used not only in reservoirs, but also in seas and oceans. Such traps can be used to study the sedimentation rate in various water ecosystems, and also the entrapped sediment can be analysed in a qualitative manner to determine its role in the distribution of pollutants deposited in the sediments of aquatic ecosystems.

scholarly journals Biomass and production of Cladocera in Furnas Reservoir, Minas Gerais, Brazil

2010 ◽  
Vol 70 (3 suppl) ◽  
pp. 879-887 ◽  
Author(s):  
RM Santos ◽  
NF. Negreiros ◽  
LC. Silva ◽  
O. Rocha ◽  
MJ. Santos-Wisniewski
Keyword(s):  
Secondary Production ◽  
Aquatic Ecosystems ◽  
Total Production ◽  
In Situ Data ◽  
Production Values ◽  
Physical And Chemical Variables ◽  
Order Of Magnitude ◽  
The Mean ◽  
Physical And Chemical

Secondary production of zooplankton, the main energy pathway in many aquatic ecosystems, is crucial to an Understanding of functioning of these systems function. In this study, we analyzed the magnitude and seasonal variations of the population density, biomass and secondary production of Cladocera in the Furnas Reservoir (Brazil). Samples were carried out monthly at 6 points in the reservoir, from August 2006 to July 2007. Main physical and chemical variables in the water column were measured in situ. Data on density, biomass and development times were obtained and used to calculate the secondary production of eight Cladocera species. The total production of Cladocera varied from 0.02 to 28.6 mgDWm-3.day-1, among the sampling sites. The highest values were recorded in spring and summer months (September to January), and were correlated to the increase in the biomass of the phytoplankton. The mean production:biomass ratio was 0.32. The level of production in Furnas Reservoir fell within the range of those reported in the literature and was of the same order of magnitude of the production values recorded for oligotrophic reservoirs. Cladocera production differed spatially inside the Sapucaí compartment and also in the temporal scale, seasonally.

Photosynthetic microbial communities in aquatic ecosystems

1982 ◽  
Vol 297 (1088) ◽  
pp. 565-574 ◽  
Keyword(s):  
Aquatic Ecosystems ◽  
Cell Envelope ◽  
Photosynthetic Apparatus ◽  
Spectral Composition ◽  
Large Lakes ◽  
Pigment Synthesis ◽  
Photosynthetic Organisms ◽  
Adaptive Processes ◽  
And Function

A critical reappraisal of our knowledge on the photosynthetic communities of the open oceans and large lakes, and the development of new approaches to measurement of their activity in situ have greatly influenced our present views on the structure and function of these communities. Based on the accumulated knowledge of the physiology and molecular biology of the photosynthetic organisms involved we can now understand some of the mechanisms underlying adaptive processes operative in Nature. The distribution pattern of the photosynthetic communities in the photic zone of aquatic ecosystems is controlled by the nature of the photosynthetic apparatus, the range of antenna pigments formed by the different organisms, and their ability to regulate quantitatively and qualitatively pigment synthesis in response to light intensity and spectral composition. An additional factor controlling distribution is the ability of many of the photosynthetic organisms to escape the oligotrophic conditions prevailing in the water column by adherence to interfaces such as the benthos or the neuston. A major factor governing the ability of organisms to adhere to these interfaces is the hydrophobicity of their cell envelope. Planktonic organisms, on the other hand, have highly hydrophilic envelopes. Benthic organisms have evolved mechanisms for dispersal, which in many cases involves the formation by the hydrophobic adherent parent cells of hydrophilic progeny cells. This has been confirmed for several hormogonia-producing cyanobacteria. Benthic photosynthetic organisms must in addition be capable of phototactic motility and have versatile metabolic patterns to adapt to the rapid fluctuations in their environment. The photosynthetic organisms of the neuston and the cyanobacteria that form surface scum share mechanisms enabling the cells to withstand conditions of photo-oxidation, lethal to most non-resistant organisms.

scholarly journals A Single Species, Micromonas pusilla (Prasinophyceae), Dominates the Eukaryotic Picoplankton in the Western English Channel

2004 ◽  
Vol 70 (7) ◽  
pp. 4064-4072 ◽  
Author(s):  
Fabrice Not ◽  
Mikel Latasa ◽  
Dominique Marie ◽  
Thierry Cariou ◽  
Daniel Vaulot ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Fluorescent In Situ Hybridization ◽  
Algal Species ◽  
Sampling Period ◽  
Single Species ◽  
English Channel ◽  
Green Algal ◽  
Micromonas Pusilla ◽  
Green Algal Species

ABSTRACT The class Prasinophyceae (Chlorophyta) contains several photosynthetic picoeukaryotic species described from cultured isolates. The ecology of these organisms and their contributions to the picoeukaryotic community in aquatic ecosystems have received little consideration. We have designed and tested eight new 18S ribosomal DNA oligonucleotide probes specific for different Prasinophyceae clades, genera, and species. Using fluorescent in situ hybridization associated with tyramide signal amplification, these probes, along with more general probes, have been applied to samples from a marine coastal site off Roscoff (France) collected every 2 weeks between July 2000 and September 2001. The abundance of eukaryotic picoplankton remained high (>103 cells ml−1) during the sampling period, with maxima in summer (up to 2 × 104 cells ml−1), and a single green algal species, Micromonas pusilla (Prasinophyceae), dominated the community all year round. Members of the order Prasinococcales and the species Bathycoccus prasinos (Mamiellales) displayed sporadic occurrences, while the abundances of all other Prasinophyceae groups targeted remained negligible.

scholarly journals Strategies to Overcome Intermediate Accumulation During in situ Nitrate Remediation in Groundwater by Hydrogenotrophic Denitrification

2021 ◽  
Vol 12 ◽  
Author(s):  
Clara Duffner ◽  
Anja Wunderlich ◽  
Michael Schloter ◽  
Stefanie Schulz ◽  
Florian Einsiedl
Keyword(s):  
Aquatic Ecosystems ◽  
Food Production ◽  
Environmental Science ◽  
Nitrogen Loading ◽  
Groundwater Systems ◽  
Lag Times ◽  
Agriculture And Food ◽  
The Eu ◽  
Stimulation Of

Bioremediation of polluted groundwater is one of the most difficult actions in environmental science. Nonetheless, the clean-up of nitrate polluted groundwater may become increasingly important as nitrate concentrations frequently exceed the EU drinking water limit of 50 mg L–1, largely due to intensification of agriculture and food production. Denitrifiers are natural catalysts that can reduce increasing nitrogen loading of aquatic ecosystems. Porous aquifers with high nitrate loading are largely electron donor limited and additionally, high dissolved oxygen concentrations are known to reduce the efficiency of denitrification. Therefore, denitrification lag times (time prior to commencement of microbial nitrate reduction) up to decades were determined for such groundwater systems. The stimulation of autotrophic denitrifiers by the injection of hydrogen into nitrate polluted regional groundwater systems may represent a promising remediation strategy for such environments. However, besides high costs other drawbacks, such as the transient or lasting accumulation of the cytotoxic intermediate nitrite or the formation of the potent greenhouse gas nitrous oxide, have been described. In this article, we detect causes of incomplete denitrification, which include environmental factors and physiological characteristics of the underlying bacteria and provide possible mitigation approaches.

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