Mariana Lozada

IBIOMAR · Laboratorio de Microbiología Ambiental

The implementation of molecular data for the analysis of nemertean diversity has unraveled the taxonomic status of several species and many higher taxa within the group. Nowadays, a large proportion of novel putative species are being discovered and it is necessary to add molecular data to the morphological description to obtain a correct identific...

Kelp forests, among the most productive ecosystems on Earth, cover large areas of the South Atlantic coast. Sediment heterotrophic bacteria have a pivotal role in the degradation of kelp biomass, however, the response of sediment microbial communities to periodic kelp biomass inputs is mostly unknown. Here, we show that kelp biomass induced rapid c...

Undaria pinnatifida is a brown algae native to Asia that has settled in various regions worldwide, periodically contributing with large quantities of C and nutrients during its annual cycle. In this work, we analyzed a coastal site in Patagonia (Argentina) that has been colonized for three decades by U. pinnatifida, focusing on associated microbial...

The European green crab Carcinus maenas and its sister species C. aestuarii are highly invasive species causing damage to coastal ecosystems and contributing to severe economic losses worldwide. C. maenas was first detected at the Atlantic Patagonian coast in 2001. In this work, we studied the diet of the green crab in a recently invaded location i...

Wastewater surveillance represents an alternative approach for the diagnosis and early detection of infectious agents of public health importance. This study aimed to evaluate SARS-CoV-2 and other quality markers in oxidation lagoons, estuarine areas and seawater at Guayas and Santa Elena in Ecuador. Sample collections were conducted twice at 42 co...

The invasive kelp Undaria pinnatifida has spread from northeastern Asia to temperate coastal environments worldwide, with profound effects on colonized ecosystems. In this work, we analyzed the effect of exudates from U. pinnatifida on the chemical and microbial properties of seawater from a semi-enclosed gulf from Atlantic Patagonia. Exudates of U...

Introduction:Cannabis plant uses are widespread across human cultures. The current tendency is to classify Cannabis varieties into chemovars upon their chemical fingerprint, mainly cannabinoids and terpenoids content. The identification of chemovars has important medical implications; however, their pharmacological characterization is costly and ti...

A Correction to this paper has been published: https://doi.org/10.1038/s41587-021-00898-4.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The invasive kelp Undaria pinnatifida has spread from northeastern Asia to temperate coastal environments worldwide, with profound effects on colonized ecosystems. In this work, we analyzed the effect of exudates from U. pinnatifida on the chemical and microbial properties of seawater from a semi-enclosed gulf from Atlantic Patagonia. Exudates of U...

The European green crab Carcinus maenas and, its sister species, C. aestuarii are highly invasive species causing damages to coastal ecosystems and severe economic losses worldwide. C. maenas was detected at the Atlantic Patagonian coast twenty years ago. In this work, we studied the diet of the green crab in a recently invaded location in Nuevo Gu...

We provide a 16S rRNA gene dataset of prokaryotic assemblages of a subantarctic marine ecosystem. Samples were collected at 2 stations (one near Ushuaia Bay and the other close to Bridges islands in the Beagle Channel). At each station, 2 depths (subsurface and bottom waters) were sampled in february, march, may and september during 2018, giving a...

Despite recent advances in metagenomics, increasing our understanding of sediment microbial communities remains a challenge because of their remarkable diversity. In this chapter we describe various strategies for the analysis of metagenomes from complex microbial communities, using a sequence dataset of coastal sediments from Antarctic and sub-Ant...

Aromatic ring-hydroxylating oxygenases (RHOs) are multicomponent enzymes that catalyze the vicinal hydroxylation of aromatic rings to produce cis-dihydrodiols, a key step in the aerobic biodegradation of aromatic compounds. In this work, we describe the characterization of three RHOs of an uncultured gammaproteobacterium from chronically polluted S...

The aim of this work was to characterize the microbial nitrogen cycling potential in sediments from Ushuaia Bay, a subantarctic environment that has suffered a recent explosive demographic growth. Subtidal sediment samples were retrieved in triplicate from two urban points in the Bay, and analyzed through metagenomic shotgun sequencing. Sequences a...

Physicochemical characteristics of Ushuaia Bay sediment samples. Results are expressed as mean and standard deviation of 10 measurements, with the exception of TOM and NH4+, which were measured in triplicate. (PDF)

Evolutionary placement analysis of putative NirK sequences identified in the metagenomes of Ushuaia Bay sediments. The tree was constructed by Maximum Likelihood in RAxML v.8.2.3. Reference sequences are indicated by GenBank accession numbers followed by title. Metagenomic sequences are indicated with blue and red colored branches, for sediment sam...

Evolutionary placement analysis of putative NosZ sequences identified in the metagenomes of Ushuaia Bay sediments. The tree was constructed by Maximum Likelihood in RAxML v.8.2.3. Reference sequences are indicated by GenBank accession numbers followed by title. Metagenomic sequences are indicated with blue and red colored branches, for OR and MC, r...

Relative abundance of the sequences assigned to Hao and NapA in various metagenomes, discriminated by type of environment. Metagenomic sequences were annotated in the IMG/M pipeline. Abundances of specific KEGG orthology (KO) identifiers were retrieved as “estimated gene copies” (assembled and unassembled fractions), normalized to the total sequenc...

Similarity percentage (SIMPER) analysis of sediment metagenomes based on abundance of amino acid sequences assigned to N-cycling biomarker genes, grouped by site. Bold types indicate biomarkers whose cumulative contribution to the relative dissimilarity was ≥ 90%. (PDF)

Relative abundance of sequences assigned to biomarker genes for N-cycling in sediments from Ushuaia Bay, discriminated by sampling site. Numbers correspond to percent amino acid sequences, with respect to total sequences assigned to KOs. Differences in abundances between sites were evaluated by Welch two-sample test (α = 0.05). *p-value <0.05; **p-...

Abundance of sequences assigned to genes encoding N-cycling enzymes selected for this study. “Estimated gene copies, assembled and unassembled metagenomes” were obtained from sequences assigned to KO identifiers at the IMG database (www.img.jgi-doe.gov). (PDF)

In this work, we analyzed the community structure and metabolic potential of sediment microbial communities in high-latitude coastal environments subjected to low to moderate levels of chronic pollution. Subtidal sediments from four low-energy inlets located in polar and subpolar regions from both Hemispheres were analyzed using large-scale 16S rRN...

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about mi...

The goal of this work was to identify sequences encoding monooxygenase biocatalysts with novel features by in silico mining an assembled metagenomic dataset of polar and subpolar marine sediments. The targeted enzyme sequences were Baeyer–Villiger and bacterial cytochrome P450 monooxygenases (CYP153). These enzymes have wide-ranging applications, f...

Rhodopsins are broadly distributed and are light sensitive molecules. In this work we analyzed 23 metagenomes corresponding to marine sediment samples from four regions which share cold climate conditions (Norway; Sweden; Argentina and Antarctica). In order to investigate the genes evolution of viral-rodopsins, an initial set of 6224 bacterial rhod...

This chapter includes the advances achieved so far in the design and implementation of molecular biological tools (MBTs) for the assessment of hydrocarbon-degrading potential in microbial communities from coastal environments of Patagonia. A brief introduction on the role of hydrocarbon-degrading bacteria in marine environments follows the basic co...

Alginates are abundant polysaccharides in brown algae that constitute an important energy source for marine heterotrophic bacteria. Despite the key role of alginate degradation processes in the marine carbon cycle, little information is available on the bacterial populations involved in these processes. The aim of this work was to gain a better und...

We aimed to gain insight into the alkane degradation potential of microbial communities from chronically polluted sediments of a subantarctic coastal environment using a combination of metagenomic approaches. A total of 6178 sequences annotated as alkane-1-monooxygenases (EC 1.14.15.3) were retrieved from a shotgun metagenomic dataset that included...

A combination of RT-PCR assays and of Northern blots were used to evaluate the ability of naphthalene, phenanthrene and pyrene to induce nahAc from three Pseudomonas isolates obtained from oil-contaminated marine sediments. Naphthalene dioxygenase activity based on indigo oxidation correlated with nahAc expression in all strains, while variable pol...

Aims: To investigate the potential to degrade polycyclic aromatic hydrocarbons (PAHs) of yet-to-be cultured bacterial populations from chronically-polluted intertidal sediments. Methods and Results: A gene variant encoding the alpha subunit of the catalytic component of an aromatic ring-hydroxylating oxygenase (RHO) was abundant in intertidal sedim...

During evolution, microorganisms have accumulated a remarkable physiological and functional heterogeneity as a result of their adaptation to various environmental selective pressures. Marine microorganisms have been evolving and diversifying during billions of years in contrast to those from terrestrial habitats, which possess a much shorter evolut...

During evolution microorganisms accumulated a remarkable physiological and functional heterogeneity as a result of their adaptation to various selective environmental pressures. Marine microorganisms have been evolving and diversifying for billions of years in contrast microorganisms from terrestrial habitats, which possess a much shorter evolution...

In previous studies we have mapped uric acid deposits in specialized tissues of the invading apple snail Pomacea canaliculata. Uric acid stores function as reservoirs of combined nitrogen in insects. The first step for recycling uric acid nitrogen involves the action of uricase and here we explored the occurrence of uricase-positive bacteria in the...

The aim of this study was to design a molecular biological tool suitable for use in marine ecosystems for environmental assessment and bioremediation, using the information provided by amplicon pyrosequencing of 16S rRNA genes. We selected from the literature 63 bacterial genera previously linked to hydrocarbon biodegradation, as representing a min...

Este libro está dirigido al público en general, con algo de conocimientos sobre las ciencias biológicas adquiridos en la escuela media. Estudiantes de este nivel educativo, estudiantes de carreras terciarias y universitarias e integrantes de las oficinas de gobiernos interesados en esta temática fueron nuestra inspiración para la selección de los t...

The gastropod Trophon geversianus exhibits shell polymorphisms along its distribution in subtidal and intertidal habitats. Our hypothesis is that morphological and behavioral patterns of T. geversianus represent habitat-specific constrains; subsequently we expect an association between shell morphology, attachment behavior, and habitat. In order to...

The marine environments of Argentina have a remarkable extension, as well as high biological productivity and biodiversity of both macro- and microorganisms. Despite having a great potential for biotechnological applications, the microorganisms inhabiting these ecosystems remain mostly unexplored and unexploited. In this review, we study the resear...

Although sediments are the natural hydrocarbon sink in the marine environment, the ecology of hydrocarbon-degrading bacteria in sediments is poorly understood, especially in cold regions. We studied the diversity of alkane-degrading bacterial populations and their response to oil exposure in sediments of a chronically polluted Subantarctic coastal...

The marine environments of Argentina have a remarkable extension, as well as high biological productivity and biodiversity of both macro- and microorganisms. Despite having a great potential for biotechnological applications, the microorganisms inhabiting these ecosystems remain mostly unexplored and unexploited. In this review, we study the resear...

Novel polycyclic aromatic hydrocarbon dioxygenase gene variants were present in abundances similar to or higher than those of phnA1 from Cycloclasticus spp. at a chronically polluted subantarctic coastal marine environment in Patagonia. These novel gene variants were detected over a 6-year time span and were also present in sediments from temperate...

Environmental microorganisms constitute an almost inexhaustible reserve of genetic and functional diversity, accumulated during millions of years of adaptive evolution to various selective pressures. In particular, the extent of microbial biodiversity in marine habitats seems to grow larger as new techniques emerge to measure it. This has resulted...

With the goal of identifying functional biomarker genes associated with polycyclic aromatic hydrocarbon (PAH) biodegradation in chronically polluted Subantarctic marine sediments, we amplified from environmental metagenomic DNA, cloned and sequenced gene fragments encoding dioxygenase enzymes associated with the biodegradation of these compounds. I...

The goal of this study was to identify functional targets to detect polycyclic aromatic hydrocarbon (PAH)-degrading bacterial populations in cold marine ecosystems. We designed a degenerate primer set targeting genes encoding the alpha subunit of PAH-dioxygenases from Gram-positive bacteria. This primer set was used to amplify gene fragments from m...

Biosurfactant-producing bacteria belonging to the genera Alcanivorax, Cobetia and Halomonas were isolated from marine sediments with a history of hydrocarbon exposure (Aristizábal and Gravina Peninsulas, Argentina). Two Alcanivorax isolates were found to form naturally occurring consortia with strains closely related to Pseudomonas putida and Micro...

Seven different intertidal marine sediments along patagonian coast of Argentina were analyzed on their intrinsic capability of degrading polycyclic aromatic hydrocarbons (PAHs). Enrichment cultures were set up for 15 days in minimal medium supplemented with naphthalene or phenantrene as a sole carbon and energy source using coastal sediment as inoc...

Supplementary information of sampling sites. Latitude, longitude and description of sampling sites.

Sequence alignment of ARHDs. Deduced amino acid sequence alignment of the ARHD gene fragments found in the libraries, and related sequences.

Polycyclic aromatic hydrocarbons (PAHs), widespread pollutants in the marine environment, can produce adverse effects in marine organisms and can be transferred to humans through seafood. Our knowledge of PAH-degrading bacterial populations in the marine environment is still very limited, and mainly originates from studies of cultured bacteria. In...

The development of bacterial communities in replicate lab-scale-activated sludge reactors degrading a non-ionic surfactant was evaluated by statistical analysis of denaturing gradient gel electrophoresis (DGGE) fingerprints. Four sequential batch reactors were fed with synthetic sewage, two of which received, in addition, 0.01% of nonylphenol ethox...

Bacterial communities were examined in replicate lab-scale activated sludge reactors after a period of several months of enrichment with non-ionic nonylphenol ethoxylate (NPE) surfactants. Four sequential batch reactors were fed with synthetic sewage, two of which received additionally NPE. Small subunit rDNA-derived denaturing gel gradient electro...

A molecular approach was used to evaluate the effect of nonylphenol ethoxylate surfactants on the bacterial diversity in lab-scale activated sludge reactors. Separate bench-scale units were fed synthetic wastewater with and without addition of branched nonylphenol ethoxylates (NPnEO). The performance of the reactors, in terms of carbonaceous remova...