Nicole Trefault

Universidad Mayor · GEMA Center for Genomics, Ecology & Environment

The West Kallaallit Nunaat (Greenland) coast, characterized by a variety of fjords, bays, and channels influenced by glacier melting and Atlantic and Arctic waters, is one of the most affected ecosystems by climate change. Here, we combine oceanography, optics, microscopy, high throughput sequencing, microalgal strain establishments, and state-of-t...

Background Marine sponges are dominant components of Antarctic benthos and representative of the high endemism that characterizes this environment. All microbial groups are part of the Antarctic sponge holobionts, but microbial eukaryotes have been studied less, and their symbiotic role still needs to be better understood. Here, we characterize the...

Seasonal phytoplankton blooms are important Arctic phenomena, contributing to global primary production and biogeochemical cycling. The decline in sea-ice extent and thickness favors a longer open-water period with impacts on phytoplankton dynamics. Arctic net productivity is influenced by microalgae living associated with sea ice, with distinct sp...

High-elevation arid regions harbor microbial communities reliant on metabolic niches and flexibility to survive under biologically stressful conditions, including nutrient limitation that necessitates the utilization of atmospheric trace gases as electron donors. Geothermal springs present “oases” of microbial activity, diversity, and abundance by...

Marine sponges host diverse microbial communities. Although we know many of its ecological patterns, a deeper understanding of the polar sponge holobiont is still needed. We combine high-throughput sequencing of ribosomal genes, including the largest taxonomic repertoire of Antarctic sponge species analyzed to date, functional metagenomics, and met...

Maritime Antarctic King George Island (South Shetland Islands) has experienced rapid warming in recent decades, but the impacts on soil organic matter (SOM) decomposition remain ambiguous. Most vegetation cover is dominated by bryophytes (mosses), whereas a few vascular plants, such as Deschampsia antarctica and Colobanthus quitensis grow intersper...

In the Antarctic Peninsula, increases in mean annual temperature are associated with the coverage and population density of the two Antarctic vascular plant species: Deschampsia antarctica and Colobanthus quitensis, potentially modifying critical soil processes. In this study, we characterized the diversity and community composition of active micro...

Phytoplankton under-ice blooms have been recently recognized as an important Arctic phenomenon for global primary production and biogeochemical cycling. Drastic sea-ice decline enables the development of early blooms, sometimes hundreds of kilometers beneath the pack ice. Baffin Bay is a semi-enclosed sea where Arctic and North Atlantic water masse...

Sponge-associated microorganisms are essential for sponge survival. They play an important role in recycling nutrients and, therefore, in the maintenance of the ecosystem. These microorganisms are diverse, species-specific, and different from those in the surrounding seawater. Bacterial sponge symbionts have been extensively studied in the tropics;...

Antarctic sponges harbor a diverse range of microorganisms that perform unique metabolic functions for nutrient cycles. Understanding how microorganisms establish functional sponge–microbe interactions in the Antarctic marine ecosystem provides clues about the success of these ancient animals in this realm. Here, we use a culture-dependent approach...

Coastal systems are highly productive areas for primary productivity and ecosystem services and host a large number of human activities. Since industrialization, metal micronutrients in these regions have increased. Phytoplankton use metals as micronutrients in metabolic processes, but in excess, had deleterious effects. In coastal systems, picoeuk...

A correction to this paper has been published: https://doi.org/10.1007/s00300-021-02834-3

Year-round reports of phytoplankton dynamics in the West Antarctic Peninsula are rare and mainly limited to microscopy and/or pigment-based studies. We analyzed the phytoplankton community from coastal waters of Fildes Bay in the West Antarctic Peninsula between January 2014 and 2015 using metabarcoding of the nuclear and plastidial 18/16S rRNA gen...

Year-round reports of phytoplankton dynamics in the West Antarctic Peninsula are rare and mainly limited to microscopy and/or pigment-based studies. We analyzed the phytoplankton community from coastal waters of Fildes Bay in the West Antarctic Peninsula between January 2014 and 2015 using metabarcoding of the nuclear and plastidial 18/16S rRNA gen...

Oxygen minimum zones (OMZs) support ocean biogeochemical cycles of global importance. The OMZ off central Chile is characterized by seasonally variable oxygen concentrations due to upwelling events. Bacterial and archaeal communities from this area have been previously described; however, picoeukaryote communities remain largely unexplored. In orde...

In order to set a base line for the observation of planktonic community changes due to global change, protistan plankton sampling in combination with phycotoxin measurements and solid phase adsorption toxin tracking (SPATT) was performed in two bays of King George Island (KGI) in January 2013 and 2014. In addition, SPATT sampling was performed in P...

Relatively little is known about the role of sponge microbiomes in the Antarctic marine environment, where sponges may dominate the benthic landscape. Specifically, we understand little about how taxonomic and functional diversity contributes to the symbiotic lifestyle and aids in nutrient cycling. Here we use functional metagenomics to investigate...

Mangroves in the Northwest Coast of South America are contaminated with heavy metals due to wastewater discharges from industries, affecting the biota from this environment. However, bacteria proliferate in these harsh environmental conditions becoming possible sentinel of these contaminations. In this study, bacterial community composition was ana...

Microbiomes are vast communities of microorganisms and viruses that populate all natural ecosystems. Viruses have been considered to be the most variable component of microbiomes, as supported by virome surveys and examples of high genomic mosaicism. However, recent evidence suggests that the human gut virome is remarkably stable compared with that...

Two novel azaspiracids (AZA) with a molecular mass of 869 Da were found in Pacific strains of Azadinium poporum and characterized by tandem mass spectrometry and high resolution mass spectrometry (HRMS). One compound, AZA-42, was found in Az. poporum strains AZFC25 and AZFC26, both isolated from the South China Sea. AZA-42 belongs to the 360-type A...

Microbiomes are vast communities of microbes and viruses that populate all natural ecosystems. Viruses have been considered the most variable component of microbiomes, as supported by virome surveys and examples of high genomic mosaicism. However, recent evidence suggests that the human gut virome is remarkably stable compared to other environments...

Phytoplankton blooms taking place during the warm season drive high productivity in Antarctic coastal seawaters. Important temporal and spatial variations exist in productivity patterns, indicating local constraints influencing the phototrophic community. Surface water in Chile Bay (Greenwich Island, South Shetlands) is influenced by freshwater fro...

Seabirds and pinnipeds play an important role in biogeochemical cycling by transferring nutrients from aquatic to terrestrial environments. Indeed, soils rich in animal depositions have generally high organic carbon, nitrogen and phosphorus contents. Several studies have assessed bacterial diversity in Antarctic soils influenced by marine animals;...

Clustering analysis considering the edaphic parameters and based on the Sørensen-Dice similarity coefficient. Soil samples: [Ct], Control; [Ag], Arctocephalus gazella; [Ml], Mirounga leonina; [Ld], Larus dominicanus; [Pa], Pygoscelis antarctica and [Pp], P. papua. (TIF)

Clustering analysis considering the OTUs obtained by pyrosequencing and based on the Sørensen-Dice similarity coefficient. Bootstrap support over 50% of 10,000 repeats is shown in the corresponding nodes. Soil samples: [Ct], Control; [Ag], Arctocephalus gazella; [Ml], Mirounga leonina; [Ld], Larus dominicanus; [Pa], Pygoscelis antarctica and [Pp],...

Venn diagram displaying the degree of overlap of bacterial OTUs among the 6 soil types. Soil samples: [Ct], Control; [Ag], Arctocephalus gazella; [Ml], Mirounga leonina; [Ld], Larus dominicanus; [Pa], Pygoscelis antarctica and [Pp], P. papua. (TIF)

Geo-referencing data of the soil samples underlying animal settlements. (DOCX)

Percentage of reads identified at bacterial subphyla level in the soil samples underlying animal settlements. (DOCX)

Larger volumes of sea ice have been thawing in the Central Arctic Ocean (CAO) during the last decades than during the past 800,000 years. Brackish brine (fed by meltwater inside the ice) is an expanding sympagic habitat in summer all over the CAO. We report for the first time the structure of bacterial communities in this brine. They are composed o...

Hypersaline environments represent some of the most challenging settings for life on Earth. Extremely halophilic microorganisms have been selected to colonize and thrive in these extreme environments by virtue of a broad spectrum of adaptations to counter high salinity and osmotic stress. Although there is substantial data on microbial taxonomic di...

Sponges belonging to genus Mycale are common and widely distributed across the oceans and represent a significant component of benthic communities in term of their biomass, which in many species is largely composed by bacteria. However, the microbial communities associated with Mycale species inhabiting different geographical areas have not been pr...

Microbial abundance List of the 25 most abundant OTUs in samples of Mycale (Oxymycale) acerata and Mycale (Aegogropila) magellanica as shown in Fig. 4.

OTUs in Mycale spp Relative abundance and taxonomy of 97% OTUs in samples of Mycale (Oxymycale) acerata and Mycale (Aegogropila) magellanica.

Microbial richness Observed (A) and estimated (B) microbial richness in samples of Mycale (Aegogropila) magellanica (blue) and Mycale (Oxymycale) acerata (red) from Rio Seco, Magallanes and from Fildes (King George Island) and South Bay (Doumer Island), WAP.

In the Porcelana Hot Spring (Northern Patagonia), true-branching cyanobacteria are the dominant primary producers in microbial mats, and they are mainly responsible for carbon and nitrogen fixation. However, little is known about their metabolic and genomic adaptations at high temperatures. Therefore, in this study, a total of 81 Fischerella therma...

In fjord systems, Harmful Algal Blooms (HABs) not only constitute a serious problem when affecting the wildlife and ecosystems, but also human health and economic activities related to the marine environment. This is mostly due to a broad spectrum of toxic compounds produced by several members of the phytoplankton. Nevertheless, a deep coverage of...

Phytoplankton cells are excellent biosensors for environmental monitoring and toxicity assessments in different natural systems. Green algae, in particular, appear to be more responsive to copper (Cu) disturbances. This is interesting considering that Cu pollution in coastal environments has increased over the last century, with enormous repercussi...

Phytoplankton cells are excellent biosensors for environmental monitoring and toxicity assessments in different natural systems. Green algae, in particular, appear to be more responsive to copper (Cu) disturbances. This is interesting considering that Cu pollution in coastal environments has increased over the last century, with enormous repercussi...

Dominant sponge communities have been described from several areas around the Antarctic. However, little remains known about sponges in shallow waters, where they have been normally reported rarely. In recent years, diverse communities have been described in several sites around King George Island and the western Antarctic Peninsula, suggesting the...

Anoxic marine zones (AMZs) impact biogeochemical cycles at the global scale, particularly the nitrogen cycle. Key microbial players from AMZs have been identified, but the majority remains unrecognized or uncharacterized. Thirty‐one single‐cell amplified genomes (SAGs) from the eastern tropical North and South Pacific AMZs were sequenced to gain in...

• The projected changes in water T° and OA constitute major threats to ecosystem functioning, services and integrity, as they can affect key functional species, thus affecting their associated ecosystem processes (Berg et al. 2010). • Sponges are important members of Antarctic benthic communities (Cárdenas et al. 2016), potentially playing a centra...

The Western Antarctic Peninsula is experiencing some of the most rapid climatic warming on the planet. The projected changes in water T° and OA constitute major threats to ecosystem functioning, services and integrity, as they can affect key functional species, thus affecting their associated ecosystem processes (Berg et al. 2010). Sponges are impo...

The projected changes in temperature and OA constitute major threats to ecosystem functioning, services and integrity, as they can affect key functional species, thus affecting their associated ecosystem processes (Berg et al. 2010). Sponges are important members of Antarctic benthic communities (Cárdenas et al. 2016), where they play important fun...

Azaspiracids (AZA), a group of lipophilic phycotoxins, are produced by some species of the marine dinophycean genus Azadinium. AZA have recently been detected in shellfish from the Southeast Pacific, however, AZA-producing species have not been recorded yet from the area. This study is the first record of the genus Azadinium and of the species Azad...

Phytoplankton is responsible for most primary production in Antarctica, but the short timescale dynamics of its size structure and composition are poorly described and understood. The abundance and composition of phytoplankton in Fildes Bay, western Antarctic Peninsula, was followed for 12 days during the summer using a range of methods, including...

Several bacteria that are associated with macroalgae can use phycocolloids as a carbon source. Strain INACH002, isolated from decomposing Porphyra (Rhodo-phyta), in King George Island, Antarctica, was screened and characterized for the ability to produce agarase and alginate-lyase enzymatic activities. Our strain INACH002 was identified as a member...

Climate change and biological invasions pose one of the greatest threats to biodiversity. Most analyses of the potential biological impacts have focused on changes in mean temperature, but changes in thermal variance may also impact native and invasive organisms, although differentially. We assessed the combined effects of the mean and the variance...

Comparación molecular de un sitio contaminado por metales pesados en el manglar de Estero de Guayaquil, Ecuador, frente a un sitio de manglar cercano no perturbado por metales pesados.

Spatial environmental heterogeneity influences diversity of organisms at different scales. Environmental filtering suggests that local environmental conditions provide habitat-specific scenarios for niche requirements, ultimately determining the composition of local communities. In this work, we analyze the spatial variation of microbial communitie...

Sponge-associated microbial communities include members from the three domains of life. In the case of bacteria, they are diverse, host specific and different from the surrounding seawater. However, little is known about the diversity and specificity of Eukarya and Archaea living in association with marine sponges. This knowledge gap is even greate...

Copper is an essential micronutrient, especially for photosynthetic organisms, but can be toxic at high concentrations. In the past years, coastal waters have been exposed to an increase in copper concentration due to anthropogenic inputs. One well known case is the Chañaral area (Easter South Pacific coast), where a long term coastal copper enrich...

Los suelos antárticos constituyen un ambiente extremo, debido a la sequedad, al frío y a la presencia de meses de total oscuridad. A pesar de esto, varios estudios han revelado que estos suelos poseen una gran diversidad bacteriana. En particular, en zonas libres de hielo donde se encuentran diferentes colonias de animales marinos, sus deposicio...

Cáhuil Lagoon in central Chile harbors distinct microbial communities in various solar salterns that are arranged as interconnected ponds with increasing salt concentrations. Here, we report the metagenome of the 3.0- to 0.2-µm fraction of the microbial community present in a crystallizer pond with 34% salinity.

Abstract A considerable progress has been made to understand the mechanisms of biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D). 2,4-D biodegradation pathway has been elucidated in many microorganisms including Cupriavidus necator JMP134 (previously known as Wautersia eutropha, Ralstonia eutropha and Alcaligenes eutrophus) and Pseudomonas s...

Antarctic waters are a particular marine environment mainly due to the strong seasonal variations that various parameters are subject to, like light availability and temperature. As in all oceanographic regions, food webs are sustained by photosynthetic microorganisms, which in the case of Antarctic environments seem to be strongly dominated by its...

Antarctic waters are a particular marine environment mainly due to the strong seasonal variations that various parameters are subject to, like light availability and temperature. As in all oceanographic regions, food webs are sustained by photosynthetic microorganisms, which in the case of Antarctic environments seem to be strongly dominated by its...

Phycotoxin distribution and abundance was determined during an oceanographic expedition along a latitudinal transect of 27° extent in the southeastern Pacific Ocean, from the fjords of Tierra del Fuego Island to offshore Copiapó in the Atacama region along the Chilean coast. Plankton samples were harvested at regular intervals during the entire cru...

We studied the microbial diversity and parts of the sulfur cycle in anoxic sediments at two marine observation stations of the FONDAP/COPAS research program on the Chilean upwelling system in Concepcion Bay (Station 7 and Station C1, 36° 36.5′ S; 73° W and 36° 31.747′ S; 72°57′ W respectively). DNA was extracted and purified from mud samples, so th...

The toxigenic freshwater cyanobacterium Cylindrospermopsis raciborskii T3 has been used as a model to study and elucidate the biosynthetic pathway of tetrahydropurine neurotoxins associated with paralytic shellfish poisoning (PSP). There are nevertheless several inconsistencies and contradictions in the toxin profile of this strain as published by...

Cupriavidus necator JMP134 has been extensively studied because of its ability to degrade chloroaromatic compounds, including the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 3-chlorobenzoic acid (3-CB), which is achieved through the pJP4-encoded chlorocatechol degradation gene clusters: tfdCIDIEIFI and tfdDIICIIEIIFII. The present work de...

Ralstonia eutropha JMP134 (pJP4) is a useful model for the study of bacterial degradation of substituted aromatic pollutants. Several key degrading capabilities, encoded by tfd genes, are located in the 88 kb, self-transmissible, IncP-1 beta plasmid pJP4. The complete sequence of the 87,688 nucleotides of pJP4, encoding 83 open reading frames (ORFs...

Ralstonia eutropha JMP134 (pJP4) grows on 3-chlorobenzoate (3-CB) or 2,4-dichlorophenoxyacetate (2,4-D). The copy number of chlorocatechol genes has been observed to be important for allowing growth of bacterial strains on chloroaromatic compounds. Despite the fact that two functional chlorocatechol degradation tfd gene clusters are harbored on pla...