Search results for "Underwater"

The role of topography and erosion in the development and architecture of shallow-water coral bioherms (Tortonian-Messinian, Cabo de Gata, SE Spain).

2009

23 pages; International audience; During the Miocene, Mediterranean shallow-water carbonates were rich in scleractinian corals, which thrive in various depositional settings. A Tortonian–Messinian bioherm belt developing in a heterozoan-dominated ramp was investigated along a 1.2 km continuous transect located in the Cabo de Gata region. The interval studied displays four depositional environments from mid-to-inner ramp, dominated by swell waves and storm energy, deposited as a single, large-scale depositional sequence during a 3rd to 4th order transgressive–regressive cycle. The bioherms grew in three phases, and were essentially composed of inplace primary frameworks. Three coral genera w…

Microbial deposits in the aftermath of the end-Permian mass extinction: A diverging case from the Mineral Mountains (Utah, USA)

2015

40 pages; International audience; The Lower Triassic Mineral Mountains area (Utah, USA) preserves diversified Smithian and Spathian reefs and bioaccumulations that contain fenestral-microbialites and various benthic and pelagic organisms. Ecological and environmental changes during the Early Triassic are commonly assumed to be associated with numerous perturbations (productivity changes, acidifica-tion, redox changes, hypercapnia, eustatism and temperature changes) post-dating the Permian–Triassic mass extinction. New data acquired in the Mineral Mountains sediments provide evidence to decipher the relationships between depositional environments and the growth and distribution of microbial …

Microbial communities of the Mediterranean rocky shore: ecology and biotechnological potential of the sea‐land transition

2019

Microbial communities from harsh environments hold great promise as sources of biotechnologically relevant strains and compounds. In the present work, we have characterized the microorganisms from the supralittoral and splash zone in three different rocky locations of the Western Mediterranean coast, a tough environment characterized by high levels of irradiation and large temperature and salinity fluctuations. We have retrieved a complete view of the ecology and functional aspects of these communities and assessed the biotechnological potential of the cultivable microorganisms. All three locations displayed very similar taxonomic profiles, with the genus Rubrobacter and the families Xenoco…

2020

The composition of phytoplankton community is the basis for environmental monitoring and assessment of the ecological status of aquatic ecosystems. Community composition studies of phytoplankton have been based on time-consuming and expertise-demanding light microscopy analyses. Molecular methods have the potential to replace microscopy, but the high copy number variation of ribosomal genes and the lack of universal primers for simultaneous amplification of prokaryotic and eukaryotic genes complicate data interpretation. In this study, we used our previously developed directional primer-independent high-throughput sequencing (HTS) approach to analyze 16S and 18S rRNA community structures. C…

In Vitro Testing of Alternative Synthetic and Natural Antiparasitic Compounds against the Monogenean Sparicotyle chrysophrii

2021

© 2021 by the authors.

A multilocus sequence analysis scheme for characterization of Flavobacterium columnare isolates

2015

Background Columnaris disease caused by Flavobacterium columnare is a serious problem in aquaculture, annually causing large economic losses around the world. Despite considerable research, the molecular epidemiology of F. columnare remains poorly understood. Methods We investigated the population structure and spatiotemporal changes in the genetic diversity of F. columnare population in Finland by using a multilocus sequence typing (MLST) and analysis (MLSA) based on DNA sequence variation within six housekeeping genes. A total of 83 strains of F. columnare were collected from eight different areas located across the country between 2003 and 2012. Results Partial sequencing of six housekee…

2015

Iron reduction in subseafloor sulfate-depleted and methane-rich marine sediments is currently a subject of interest in subsurface geomicrobiology. While iron reduction and microorganisms involved have been well studied in marine surface sediments, little is known about microorganisms responsible for iron reduction in deep methanic sediments. Here, we used quantitative PCR (Q-PCR)-based 16S rRNA gene copy numbers and pyrosequencing-based relative abundances of bacteria and archaea to investigate covariance between distinct microbial populations and specific geochemical profiles in the top 5 m of sediment cores from the Helgoland mud area, North Sea. We found that gene copy numbers of bacteri…

Dissemination of CTX-M-Producing Escherichia coli in Freshwater Fishes From a French Watershed (Burgundy)

2019

International audience; The burden of extended-spectrum beta-lactamases producing Escherichia coli (ESBL-Ec), has increased over several decades. Freshwater ecosystems are suspected to play an important ecological and evolutionary role in driving the dissemination of antimicrobial resistance. The aim of our study was to decipher the occurrence of ESBL-Ec in a small watershed (Ouche river, Burgundy, France), targeting environmental matrices and fishes. Among cefotaxime resistant E. coli (ctxR Ec) isolates, we detected and characterized 36 ESBL-Ec from water, biofilm and fish guts. ctxR Ec and ESBL-Ec were found in samples from sites near the first small town, located downstream from the wate…

Comparing the different morphotypes of a fish pathogen - implications for key virulence factors in Flavobacterium columnare

2014

Background: Flavobacterium columnare (Bacteroidetes) is the causative agent of columnaris disease in farmed freshwater fish around the world. The bacterium forms three colony morphotypes (Rhizoid, Rough and Soft), but the differences of the morphotypes are poorly known. We studied the virulence of the morphotypes produced by F. columnare strain B067 in rainbow trout ( Onconrhynchus mykiss ) and used high-resolution scanning electron microscopy to identify the fine structures of the cells grown in liquid and on agar. We also analysed the proteins secreted extracellularly and in membrane vesicles to identify possible virulence factors. Results: Only the Rhizoid morphotype was virulent in rain…

Functional gene pyrosequencing reveals core proteobacterial denitrifiers in boreal lakes

2015

Denitrification is an important microbial process in aquatic ecosystems that can reduce the effects of eutrophication. Here, quantification and pyrosequencing of nirS, nirK, and nosZ genes encoding for nitrite and nitrous oxide reductases was performed in sediment samples from four boreal lakes to determine the structure and seasonal stability of denitrifying microbial populations. Sediment quality and nitrate concentrations were linked to the quantity and diversity of denitrification genes, the abundance of denitrifying populations (nirS and nosZ genes) correlated with coupled nitrificationdenitrification (Dn), and the denitrification of the overlying water NO3 − (Dw) correlated with the n…