scholarly journals Ingestion rate and grazing impact by the mixotrophic ciliate Mesodinium rubrum on natural populations of marine heterotrophic bacteria in the coastal waters of Korea

ALGAE ◽  
2017 ◽  
Vol 32 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Kyeong Ah Seong ◽  
Geumog Myung ◽  
Hae Jin Jeong ◽  
Wonho Yih ◽  
Hyung Seop Kim ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Heterotrophic Bacteria ◽  
Ingestion Rate ◽  
Natural Populations ◽  
Grazing Impact ◽  
Mesodinium Rubrum ◽  
Marine Heterotrophic Bacteria

Mixotrophy in the marine red-tide cryptophyte Teleaulax amphioxeia and ingestion and grazing impact of cryptophytes on natural populations of bacteria in Korean coastal waters

Harmful Algae ◽  
2017 ◽  
Vol 68 ◽  
pp. 105-117 ◽  
Author(s):  
Yeong Du Yoo ◽  
Kyeong Ah Seong ◽  
Hae Jin Jeong ◽  
Wonho Yih ◽  
Jung-Rae Rho ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Red Tide ◽  
Natural Populations ◽  
Grazing Impact

Resistance to copper ions and antibiotics in marine heterotrophic bacteria in the coastal waters of Vietnam

2011 ◽  
Vol 37 (4) ◽  
pp. 284-290 ◽  
Author(s):  
I. A. Beleneva ◽  
A. D. Kukhlevsky ◽  
U. V. Kharchenko ◽  
Yu. L. Kovalchuk
Keyword(s):  
Coastal Waters ◽  
Heterotrophic Bacteria ◽  
Copper Ions ◽  
Marine Heterotrophic Bacteria

scholarly journals Simulating the Impact of the Internal Structure of Phytoplankton on the Bulk Particulate Backscattering Ratio using a Two-Layered Spherical Geometry for Cells

2018 ◽  
Author(s):  
Lucile Duforêt-Gaurier ◽  
David Dessailly ◽  
William Moutier ◽  
Hubert Loisel
Keyword(s):  
Coastal Waters ◽  
Natural Waters ◽  
Heterotrophic Bacteria ◽  
Relative Concentration ◽  
Spherical Geometry ◽  
The Third ◽  
Study Case ◽  
Coated Spheres ◽  
The Impact ◽  
Phytoplankton Cells

The bulk backscattering ratio ($\tilde{b_{bp}}$) is commonly used as a descriptor of the bulk real refractive index of the particulate assemblage in natural waters. Based on numerical simulations, we analyze the impact of heterogeneity of phytoplankton cells on $\tilde{b_{bp}}$. $\tilde{b_{bp}}$ is modeled considering viruses, heterotrophic bacteria, phytoplankton, detritus, and minerals. Three study cases are defined according to the relative abundance of these different components. Two study cases represent typical situations in open ocean, outside (No-B/No-M) and inside bloom (B/No-M). The third study case is typical of coastal waters with the presence of minerals. Phytoplankton cells are modeled by a two-layered spherical geometry representing a chloroplast surrounding the cytoplasm. The $\tilde{b_{bp}}$ values are higher when heterogeneity is considered because the contribution of coated spheres to backscattering is higher than homogeneous spheres. The impact of heterogeneity is however strongly conditioned by the hyperbolic slope $\xi$ of the particle size distribution. Even if the relative concentration of phytoplankton is small (<1%), $\tilde{b_{bp}}$ increases by about 60% (for $\xi=4.3$ and for the No-B/No-M water body), when the heterogeneity is taken into account, in comparison with a particulate population only composed by homogeneous spheres. As expected, heterogeneity has a much smaller impact (about 5$\%$ for $\xi=4.3$) on $\tilde{b_{bp}}$ when minerals are added.

scholarly journals Evaluation of culturable, nitrifying, ammonium-oxidizing, and metabolically active bacteria in shrimp farm effluents of Kino Bay, Sonora, México

2012 ◽  
Vol 64 (3) ◽  
pp. 895-909 ◽  
Author(s):  
Nolberta Huerta-Aldaz ◽  
M.A. López-Torres ◽  
J.E. Valdez-Holguín ◽  
R.H. Barraza-Guardado
Keyword(s):  
Heterotrophic Bacteria ◽  
Natural Populations ◽  
Control Site ◽  
Epifluorescence Microscopy ◽  
Nitrifying Bacteria ◽  
Production Cycle ◽  
Mean Values ◽  
Discharge Area ◽  
Shrimp Farm ◽  
Active Bacteria

Bacteria from shrimp farm effluents in Kino Bay, Sonora, M?xico were evaluated during the 2008 production cycle. The culturable bacterial populations considered were viable heterotrophic bacteria (VHB) and Vibrio-like bacteria (VLB). In addition, total bacteria (TB), metabolically active bacteria (MAB), nitrifying bacteria (NB), and ammonium-oxidizing bacteria (AOB) were quantified by epifluorescence microscopy. Three sampling sites were established in the influence area of drain and one control site far from the discharge area. Average concentrations of VHB and VLB were 103 and 102 CFU mL-1, respectively. The TB ranged from 107 to 109 cells mL-1. The mean values of Mrelated to TB counts in the affected area were higher throughout the culture cycle compared to the control site, ranging from 1.09 to 27.35%. These results indicate that effluents modify the natural loads of bacteria in the discharge area, which could affect natural populations and the microbial balance of the area.

scholarly journals Quorum Sensing Regulates the Hydrolytic Enzyme Production and Community Composition of Heterotrophic Bacteria in Coastal Waters

2021 ◽  
Vol 12 ◽  
Author(s):  
Marion Urvoy ◽  
Raphaël Lami ◽  
Catherine Dreanno ◽  
Daniel Delmas ◽  
Stéphane L’Helguen ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Community Composition ◽  
Coastal Waters ◽  
Bacterial Communities ◽  
Heterotrophic Bacteria ◽  
Bacterial Community Composition ◽  
Marine Ecosystem ◽  
Hydrolytic Enzyme ◽  
Enzymatic Activities ◽  
Hydrolytic Activities

Heterotrophic microbial communities play a central role in biogeochemical cycles in the ocean by degrading organic matter through the synthesis of extracellular hydrolytic enzymes. Their hydrolysis rates result from the community’s genomic potential and the differential expression of this genomic potential. Cell-cell communication pathways such as quorum sensing (QS) could impact both aspects and, consequently, structure marine ecosystem functioning. However, the role of QS communications in complex natural assemblages remains largely unknown. In this study, we investigated whether N-acylhomoserine lactones (AHLs), a type of QS signal, could regulate both hydrolytic activities and the bacterial community composition (BCC) of marine planktonic assemblages. To this extent, we carried out two microcosm experiments, adding five different AHLs to bacterial communities sampled in coastal waters (during early and peak bloom) and monitoring their impact on enzymatic activities and diversity over 48 h. Several specific enzymatic activities were impacted during both experiments, as early as 6 h after the AHL amendments. The BCC was also significantly impacted by the treatments after 48 h, and correlated with the expression of the hydrolytic activities, suggesting that changes in hydrolytic intensities may drive changes in BCC. Overall, our results suggest that QS communication could participate in structuring both the function and diversity of marine bacterial communities.

scholarly journals Structure-Function Analysis Indicates that an Active-Site Water Molecule Participates in Dimethylsulfoniopropionate Cleavage by DddK

2019 ◽  
Vol 85 (8) ◽  
Author(s):  
Ming Peng ◽  
Xiu-Lan Chen ◽  
Dian Zhang ◽  
Xiu-Juan Wang ◽  
Ning Wang ◽  
...  
Keyword(s):  
Water Molecule ◽  
Active Site ◽  
Dimethyl Sulfide ◽  
Catalytic Mechanism ◽  
Heterotrophic Bacteria ◽  
Function Analysis ◽  
Cloud Condensation Nuclei ◽  
Oxidation Products ◽  
Condensation Nuclei ◽  
Marine Heterotrophic Bacteria

ABSTRACT The osmolyte dimethylsulfoniopropionate (DMSP) is produced in petagram quantities in marine environments and has important roles in global sulfur and carbon cycling. Many marine microorganisms catabolize DMSP via DMSP lyases, generating the climate-active gas dimethyl sulfide (DMS). DMS oxidation products participate in forming cloud condensation nuclei and, thus, may influence weather and climate. SAR11 bacteria are the most abundant marine heterotrophic bacteria; many of them contain the DMSP lyase DddK, and their dddK transcripts are relatively abundant in seawater. In a recently described catalytic mechanism for DddK, Tyr64 is predicted to act as the catalytic base initiating the β-elimination reaction of DMSP. Tyr64 was proposed to be deprotonated by coordination to the metal cofactor or its neighboring His96. To further probe this mechanism, we purified and characterized the DddK protein from Pelagibacter ubique strain HTCC1062 and determined the crystal structures of wild-type DddK and its Y64A and Y122A mutants (bearing a change of Y to A at position 64 or 122, respectively), where the Y122A mutant is complexed with DMSP. The structural and mutational analyses largely support the catalytic role of Tyr64, but not the method of its deprotonation. Our data indicate that an active water molecule in the active site of DddK plays an important role in the deprotonation of Tyr64 and that this is far more likely than coordination to the metal or His96. Sequence alignment and phylogenetic analysis suggest that the proposed catalytic mechanism of DddK has universal significance. Our results provide new mechanistic insights into DddK and enrich our understanding of DMS generation by SAR11 bacteria. IMPORTANCE The climate-active gas dimethyl sulfide (DMS) plays an important role in global sulfur cycling and atmospheric chemistry. DMS is mainly produced through the bacterial cleavage of marine dimethylsulfoniopropionate (DMSP). When released into the atmosphere from the oceans, DMS can be photochemically oxidized into DMSO or sulfate aerosols, which form cloud condensation nuclei that influence the reflectivity of clouds and, thereby, global temperature. SAR11 bacteria are the most abundant marine heterotrophic bacteria, and many of them contain DMSP lyase DddK to cleave DMSP, generating DMS. In this study, based on structural analyses and mutational assays, we revealed the catalytic mechanism of DddK, which has universal significance in SAR11 bacteria. This study provides new insights into the catalytic mechanism of DddK, leading to a better understanding of how SAR11 bacteria generate DMS.

scholarly journals Habitat and taxon as driving forces of carbohydrate catabolism in marine heterotrophic bacteria: example of the model algae-associated bacteriumZobellia galactanivoransDsijT

2016 ◽  
Vol 18 (12) ◽  
pp. 4610-4627 ◽  
Author(s):  
Tristan Barbeyron ◽  
François Thomas ◽  
Valérie Barbe ◽  
Hanno Teeling ◽  
Chantal Schenowitz ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Driving Forces ◽  
Marine Heterotrophic Bacteria ◽  
Carbohydrate Catabolism

Metal-Resistant Heterotrophic Bacteria in Coastal Waters of Primorye

2005 ◽  
Vol 31 (2) ◽  
pp. 73-77 ◽  
Author(s):  
I. P. Bezverbnaya ◽  
L. S. Buzoleva ◽  
N. S. Khristoforova
Keyword(s):  
Coastal Waters ◽  
Heterotrophic Bacteria
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