Mayara Ogaki - Academia.edu (original) (raw)

Papers by Mayara Ogaki

Springer Polar Sciences, 2019

Springer Polar Sciences Springer Polar Sciences is an interdisciplinary book series that is dedic... more Springer Polar Sciences Springer Polar Sciences is an interdisciplinary book series that is dedicated to research in the Arctic, sub-Arctic regions, and the Antarctic. In recent years, the polar regions have received increased scientific and public interest. Both the Arctic and Antarctic have been recognized as key regions in the regulation of the global climate, and polar ecosystems have been identified to be particularly susceptible to the ongoing environmental changes. Consequently, the international efforts in polar research have been enhanced considerably, and a wealth of new findings is being produced at a growing rate by the international community of polar researchers. Springer Polar Sciences aims to present a broad platform that will include stateof-the-art research, bringing together both science and humanities to facilitate an exchange of knowledge between the various polar science communities. The Series offers an outlet to publish contributions, monographs, edited works, conference proceedings, etc. Topics and perspectives will be broad and will include, but not be limited to: climate change impacts, environmental change, polar ecology, governance, health, economics, indigenous populations, tourism and resource extraction activities. Books published in the series will appeal to scientists, students, polar researchers and policy makers.

Brazilian Journal of Microbiology

Molecular Biology Reports, 2021

BACKGROUND Vega Island is located off the eastern tip of the Antarctic Peninsula (Maritime Antarc... more BACKGROUND Vega Island is located off the eastern tip of the Antarctic Peninsula (Maritime Antarctica), in the Weddell Sea. In this study, we used metabarcoding to investigate green algal DNA sequence diversity present in sediments from three lakes on Vega Island (Esmeralda, Copépodo, and Pan Negro Lakes). METHODS AND RESULTS Total DNA was extracted and the internal transcribed spacer 2 region of the nuclear ribosomal DNA was used as a DNA barcode for molecular identification. Green algae were represented by sequences representing 78 taxa belonging to Phylum Chlorophyta, of which 32% have not previously been recorded from Antarctica. Sediment from Pan Negro Lake generated the highest number of DNA reads (11,205), followed by Esmeralda (9085) and Copépodo (1595) Lakes. Esmeralda Lake was the richest in terms of number of taxa (59), with Copépodo and Pan Negro Lakes having 30 taxa each. Bray-Curtis dissimilarity among lakes was high (~ 0.80). The Order Chlamydomonadales (Chlorophyceae) gave the highest contribution in terms of numbers of taxa and DNA reads in all lakes. The most abundant taxon was Chlorococcum microstigmatum. CONCLUSIONS The study confirms the utility of DNA metabarcoding in assessing potential green algal diversity in Antarctic lakes, generating new Antarctic records.

Fungal Biology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Probiotics and Antimicrobial Proteins, 2021

Antarctica is one of the most pristine and inhospitable regions of the planet, mostly inhabited b... more Antarctica is one of the most pristine and inhospitable regions of the planet, mostly inhabited by microorganisms that survive due to unusual metabolic pathways to adapt to its extreme conditions, which could be interesting for the selection of new probiotics. The aim of the present study was to screen in vitro and in vivo putative probiotics among 254 yeasts isolated from different habitats of Antarctica. In vitro selection evaluated functional (growth at 37 °C, resistance to simulated gastric environment, and to bile salts), safety (degradation of mucin, production of β-haemolysis and resistance to antifungal drugs), and beneficial (production of antagonistic substances and adhesion to pathogens) properties. Twelve yeasts were able to grow at 37 °C, one of which was eliminated to present β-haemolytic ability. The remained yeasts resisted to gastric simulation and bile salts, but none presented antagonism against the pathogens tested. Because of the high co-aggregation with Salmonella enterica Typhimurium and growth yield, Rhodotorula mucilaginosa UFMGCB 18377 and Saccharomyces cerevisiae UFMGCB 11120 were selected for in vivo steps using mice challenged with S. Typhimurium. Both yeasts reached high faecal population levels when daily administered, but only R. mucilaginosa UFMGCB 18377 protected mice against Salmonella infection presenting a higher survival and reduced weight loss, bacterial translocation to the liver, sIgA intestinal levels, and intestinal and hepatic MPO and EPO activities. Our in vitro and in vivo results suggest that R. mucilaginosa UFMGCB 18377 presents probiotic potential and deserve further studies as candidate of probiotic by-products. In addition, this is the first screening study of yeasts isolated from Antarctic environments and of Rhodotorula genus for probiotic use.

Fungi of Antarctica, 2019

The biota of Antarctica lakes is constituted by simplified aquatic food webs characterised by low... more The biota of Antarctica lakes is constituted by simplified aquatic food webs characterised by low zooplankton biomass, absence of fish, and low floristic diversity (algae and aquatic mosses), but primarily encompassing microorganisms such as viruses, cyanobacteria, bacteria, archaea, and fungi. Among the microbial communities, fungi are widely spread in the different Antarctic lakes and, despite the extreme conditions of the region, show moderate diversity and richness with dominance of a few taxa. Endemic fungal species are found in the Antarctic lakes; however, the majority of fungi are characterised as cosmopolitan cold-adapted species that arrive as propagules from outside Antarctica and are adapted to disperse in the temporary or perennial water bodies, including saline and freshwater lakes. These fungi are subjected to freezing and melting cycles, low temperatures, and high incidence of UV radiation, mainly during the long periods of light in Austral summers. In contrast, in Austral winters, fungi are exposed to extreme freezing conditions. Additionally, in the lakes of Antarctica, fungi act as decomposers and interact with other organisms, such as parasites, or are in symbiotic associations, which consequently influence the lake food web dynamics. In Antarctica, cold-adapted cosmopolitan and psychrophilic fungi have the ability to grow, colonise substrates, and produce extracellular cold-active enzymes and other metabolites, which actively participate in the cycling of nutrients in lakes. In this chapter, we present the characteristics of different Antarctic lakes and shed light on various aspects of taxonomy, ecology, and potential applications of freshwater fungi from maritime and continental Antarctica.

Microbial Ecology, 2021

We assessed fungal diversity in deep-sea sediments obtained from different depths in the Southern... more We assessed fungal diversity in deep-sea sediments obtained from different depths in the Southern Ocean using the internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA by metabarcoding through high-throughput sequencing (HTS). We detected 655,991 DNA reads representing 263 fungal amplicon sequence variants (ASVs), dominated by Ascomycota , Basidiomycota , Mortierellomycota , Mucoromycota , Chytridiomycota and Rozellomycota , confirming that deep-sea sediments can represent a hotspot of fungal diversity in Antarctica. The community diversity detected included 17 dominant fungal ASVs, 62 intermediate and 213 rare. The dominant fungi included taxa of Mortierella , Penicillium , Cladosporium , Pseudogymnoascus , Phaeosphaeria and Torula . Despite the extreme conditions of the Southern Ocean benthos, the total fungal community detected in these marine sediments displayed high indices of diversity and richness, and moderate dominance, which varied between the different depths sampled. The highest diversity indices were obtained in sediments from 550 m and 250 m depths. Only 49 ASVs (18.63%) were detected at all the depths sampled, while 16 ASVs were detected only in the deepest sediment sampled at 1463 m. Based on sequence identities, the fungal community included some globally distributed taxa, primarily recorded otherwise from terrestrial environments, suggesting transport from these to deep marine sediments. The assigned taxa included symbionts, decomposers and plant-, animal- and human-pathogenic fungi, suggesting that deep-sea sediments host a complex fungal diversity, although metabarcoding does not itself confirm that living or viable organisms are present.

Scientific Reports, 2020

We assessed soil fungal diversity at two sites on Deception Island, South Shetland Islands, Antar... more We assessed soil fungal diversity at two sites on Deception Island, South Shetland Islands, Antarctica using DNA metabarcoding analysis. The first site was a relatively undisturbed area, and the second was much more heavily impacted by research and tourism. We detected 346 fungal amplicon sequence variants dominated by the phyla Ascomycota, Basidiomycota, Mortierellomycota and Chytridiomycota. We also detected taxa belonging to the rare phyla Mucoromycota and Rozellomycota, which have been difficult to detect in Antarctica by traditional isolation methods. Cladosporium sp., Pseudogymnoascus roseus, Leotiomycetes sp. 2, Penicillium sp., Mortierella sp. 1, Mortierella sp. 2, Pseudogymnoascus appendiculatus and Pseudogymnoascus sp. were the most dominant fungi. In addition, 440,153 of the total of 1,214,875 reads detected could be classified only at the level of Fungi. In both sampling areas the DNA of opportunistic, phytopathogenic and symbiotic fungi were detected, which might have b...

Springer Polar Sciences, 2019

Fungi are well known for their important roles in terrestrial ecosystems, but filamentous and yea... more Fungi are well known for their important roles in terrestrial ecosystems, but filamentous and yeast forms are also active components of microbial communities from marine ecosystems. Marine fungi are particularly abundant and relevant in coastal systems where they can be found in association with large organic substrata, like seaweeds. Antarctica is a rather unexplored region of the planet that is being influenced by strong and rapid climate change. In the past decade, several efforts have been made to get a thorough inventory of marine fungi from different environments, with a particular emphasis on those associated with the large communities of seaweeds that abound in littoral and infralittoral ecosystems. The algicolous fungal communities obtained were characterized by a few dominant species and a large number of singletons, as well as a balance among endemic, indigenous, and cold-adapted cosmopolitan species. The long-term monitoring of this balance and the dynamics of richness, dominance, and distributional patterns of these algicolous fungal communities is proposed to understand and model the influence of climate change on the maritime Antarctic biota. In addition, several fungal isolates from marine Antarctic environments have shown great potential as producers of bioactive natural products and enzymes and may represent attractive sources of biotechnological products.

Extremophiles, 2021

We evaluated the fungal diversity in two lakes on the South Shetland Islands, using DNA metabarco... more We evaluated the fungal diversity in two lakes on the South Shetland Islands, using DNA metabarcoding through high-throughput sequencing (HTS). A microcosm experiment was deployed for two consecutive years in lakes on Deception and King George islands to capture potential decomposer freshwater fungi. Analyses of the baits revealed 258,326 DNA reads distributed in 34 fungal taxa of the phyla Ascomycota , Basidiomycota , Mortierellomycota , Chytridiomycota and Rozellomycota . Tetracladium marchalianum , Tetracladium sp., Rozellomycota sp., Fungal sp. 1 and Fungal sp. 2 were the most common taxa detected. However, the majority of the communities comprised intermediate and rare taxa. Both fungal communities displayed moderate indices of diversity, richness and dominance. Only six taxa were detected in both lakes, including the most dominant T. marchalianum and Tetracladium sp. The high numbers of reads of the known aquatic saprotrophic hyphomycetes T. marchalianum and Tetracladium sp. in the baits suggest that these fungi may digest organic material in Antarctic lakes, releasing available carbon and nutrients to the other aquatic organisms present in the complex lake food web. Our data confirm that the use of cotton baits together with HTS approaches can be appropriate to study the diversity of resident freshwater fungi present in Antarctic lakes.

Extremophiles, 2020

In this study, we accessed culturable fungal assemblages present in the sediments of three lakes ... more In this study, we accessed culturable fungal assemblages present in the sediments of three lakes potentially impacted anthropogenically in the Fildes Peninsula, King George Island, Antarctica and identified 63 taxa. Cladosporium sp. 2, Pseudeurotium hygrophilum , and Pseudogymnoascus verrucosus were recovered from the sampled sediments of all lakes. High concentrations of metals and the lowest fungal diversity indices were detected in the sediments of the Central Lake, which can be influenced by human activities due to their proximity to research stations to those of the other two lakes, which were far from the Antarctic stations. At least one type of biological activity was demonstrated by 40 fungal extracts. Among these, P. hygrophilum , P. verrucosus , Penicillium glabrum , and Penicillium solitum demonstrated strong trypanocidal, herbicidal, and antifungal activities. Our results suggest that an increase of the anthropogenic activities in the region might have affected the microbial diversity and composition. In addition, the fungal diversity in these lakes may be a useful model to study the effect of anthropogenic activities in Antarctica. We isolated a diverse group of fungal taxa from Antarctic lake sediments, which have the potential to produce novel compounds for the both the medical and agriculture sectors.

Extremophiles, 2019

We accessed the culturable mycobiota present in marine sediments at different depths in Antarctic... more We accessed the culturable mycobiota present in marine sediments at different depths in Antarctica Ocean. Acremonium fusidioides, Penicillium allii-sativi, Penicillium chrysogenum, Penicillium palitans, Penicillium solitum, and Pseudogymnoascus verrucosus were identified. Penicillium allii-sativi was the dominant species. At least one isolate of each species was capable to present antifungal, trypanocidal, leishmanicidal, antimalarial, nematocidal, or herbicidal activities. Penicillium produced extracts with strong trypanocidal and antimalarial activities, and the extracts of P. solitum and P. chrysogenum demonstrated strong antimalarial activities. Acremonium fusidioides and P. verrucosus displayed strong selective herbicidal properties. The 1 H NMR signals for extracts of A. fusidioides, P. chrysogenum, and P. solitum indicated the presence of highly functionalized secondary metabolites, which may be responsible for the biological activities detected. In the deep marine Antarctic sediments, we detected fungal assemblages in which the Penicillium species were found to be dominant and demonstrated capabilities to survive and/or colonise that poly-extreme habitat. Penicillium being a polyextremophile Antarctic species, exhibited strong biological activities and the presence of aromatic compounds in its extracts may indicate that they are wild ancient strains with high genetic and biochemical potentials that enable them to produce bioactive compounds which can be researched in further studies and used in the chemotherapy of neglected tropical diseases as well as in agriculture.

Revista da Sociedade Brasileira de Medicina Tropical, 2019

Introduction: Administration of total parenteral nutrition (TPN) via catheters increases the risk... more Introduction: Administration of total parenteral nutrition (TPN) via catheters increases the risk for candidemia from Candida parapsilosis. Methods: C. parapsilosis sensu stricto blood isolates were evaluated for ability total biomass biofilm formation and morphogenesis in presence of glucose at TPN equivalent concentrations. Results: Biofilms were increased at high glucose concentrations (25-30%) compared to the control medium. Significant increase in filamentous forms was observed in cultures with 30% glucose. Conclusions: Biofilm formation by C. parapsilosis sensu stricto in hyperglycidic medium may contribute to its pathogenic potential for fungemia related to TPN catheters.

Brazilian Journal of Food Technology, 2015

Resumo Bacteriocinas são peptídeos antimicrobianos sintetizados nos ribossomos, tendo sido descri... more Resumo Bacteriocinas são peptídeos antimicrobianos sintetizados nos ribossomos, tendo sido descrita uma grande diversidade de bacteriocinas, as quais diferem entre si quanto a composição de aminoácidos, biossíntese, transporte e modo de ação. Nos alimentos, as bacteriocinas podem ser encontradas naturalmente como produtos da microbiota normal ou introduzida (cultura starter ou probióticos). Devido às suas aplicabilidades frente a organismos patogênicos contaminantes em alimentos, vários estudos têm sido publicados, tornando o uso destes peptídeos uma alternativa aos conservantes químicos tradicionais. Considerando-se as propriedades das bacteriocinas e sua potencial aplicação como bioconservadores de alimentos e alternativa aos antibióticos, o presente estudo busca acercar-se de uma visão geral das bacteriocinas quanto aos aspectos históricos, sistemas de classificação, biossíntese e transporte, modo de ação, abordando também algumas de suas aplicações na indústria de alimentos.

Journal of microbiology and biotechnology, Jan 24, 2016

In the current study, a total of 135 enterococci strains from different sources were searched for... more In the current study, a total of 135 enterococci strains from different sources were searched for the presence of enterocin-encoding genes entA, entP, entB, entL50A and entL50B. Enterocin genes occurred at different frequencies where entA was the most frequent, followed by entP and entB; entL50A and L50B were not detected. The frequency of genes occurring singly was higher than in multiple combinations. The 80 isolates that harbor at least one enterocin-encoding gene (denoted "Gene(+) strains") were screened for antimicrobial activity. Some 82.5% of the Gene(+) strains inhibited at least one of the indicator strains, besides, the isolates harboring multiple enterocin-encoding genes inhibited a larger number of indicators strains than isolates harboring a single gene. The indicator strains that exhibited growth inhibition include Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 6538, Listeria innocua CLIP 12612, Listeria monocytogenes CDC 4555, Enteroc...

Marine Microbial Bioremediation, 2021

Extremophiles : life under extreme conditions, 2021

We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north... more We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north-east Antarctic Peninsula using metabarcoding through high-throughput sequencing (HTS). A total of 640,902 fungal DNA reads were detected, which were assigned to 224 taxa of the phyla Ascomycota, Rozellomycota, Basidiomycota, Chytridiomycota and Mortierellomycota, in rank order of abundance. The most abundant genera were Pseudogymnoascus, Penicillium and Mortierella. However, a majority (423,508, 66%) of the reads, representing by 43 ASVs, could only be assigned at higher taxonomic levels and may represent taxa not currently included in the sequence databases used or be new or previously unreported taxa present in Antarctic lakes. The three lakes were characterized by high sequence diversity, richness, and moderate dominance indices. The ASVs were dominated by psychrotolerant and cosmopolitan cold-adapted Ascomycota, Basidiomycota and Mortierellomycota commonly reported in Antarctic envi...

Proceedings of the XII Latin American Congress on Food Microbiology and Hygiene, 2014

Springer Polar Sciences, 2019

Springer Polar Sciences Springer Polar Sciences is an interdisciplinary book series that is dedic... more Springer Polar Sciences Springer Polar Sciences is an interdisciplinary book series that is dedicated to research in the Arctic, sub-Arctic regions, and the Antarctic. In recent years, the polar regions have received increased scientific and public interest. Both the Arctic and Antarctic have been recognized as key regions in the regulation of the global climate, and polar ecosystems have been identified to be particularly susceptible to the ongoing environmental changes. Consequently, the international efforts in polar research have been enhanced considerably, and a wealth of new findings is being produced at a growing rate by the international community of polar researchers. Springer Polar Sciences aims to present a broad platform that will include stateof-the-art research, bringing together both science and humanities to facilitate an exchange of knowledge between the various polar science communities. The Series offers an outlet to publish contributions, monographs, edited works, conference proceedings, etc. Topics and perspectives will be broad and will include, but not be limited to: climate change impacts, environmental change, polar ecology, governance, health, economics, indigenous populations, tourism and resource extraction activities. Books published in the series will appeal to scientists, students, polar researchers and policy makers.

Brazilian Journal of Microbiology

Molecular Biology Reports, 2021

BACKGROUND Vega Island is located off the eastern tip of the Antarctic Peninsula (Maritime Antarc... more BACKGROUND Vega Island is located off the eastern tip of the Antarctic Peninsula (Maritime Antarctica), in the Weddell Sea. In this study, we used metabarcoding to investigate green algal DNA sequence diversity present in sediments from three lakes on Vega Island (Esmeralda, Copépodo, and Pan Negro Lakes). METHODS AND RESULTS Total DNA was extracted and the internal transcribed spacer 2 region of the nuclear ribosomal DNA was used as a DNA barcode for molecular identification. Green algae were represented by sequences representing 78 taxa belonging to Phylum Chlorophyta, of which 32% have not previously been recorded from Antarctica. Sediment from Pan Negro Lake generated the highest number of DNA reads (11,205), followed by Esmeralda (9085) and Copépodo (1595) Lakes. Esmeralda Lake was the richest in terms of number of taxa (59), with Copépodo and Pan Negro Lakes having 30 taxa each. Bray-Curtis dissimilarity among lakes was high (~ 0.80). The Order Chlamydomonadales (Chlorophyceae) gave the highest contribution in terms of numbers of taxa and DNA reads in all lakes. The most abundant taxon was Chlorococcum microstigmatum. CONCLUSIONS The study confirms the utility of DNA metabarcoding in assessing potential green algal diversity in Antarctic lakes, generating new Antarctic records.

Fungal Biology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Probiotics and Antimicrobial Proteins, 2021

Antarctica is one of the most pristine and inhospitable regions of the planet, mostly inhabited b... more Antarctica is one of the most pristine and inhospitable regions of the planet, mostly inhabited by microorganisms that survive due to unusual metabolic pathways to adapt to its extreme conditions, which could be interesting for the selection of new probiotics. The aim of the present study was to screen in vitro and in vivo putative probiotics among 254 yeasts isolated from different habitats of Antarctica. In vitro selection evaluated functional (growth at 37 °C, resistance to simulated gastric environment, and to bile salts), safety (degradation of mucin, production of β-haemolysis and resistance to antifungal drugs), and beneficial (production of antagonistic substances and adhesion to pathogens) properties. Twelve yeasts were able to grow at 37 °C, one of which was eliminated to present β-haemolytic ability. The remained yeasts resisted to gastric simulation and bile salts, but none presented antagonism against the pathogens tested. Because of the high co-aggregation with Salmonella enterica Typhimurium and growth yield, Rhodotorula mucilaginosa UFMGCB 18377 and Saccharomyces cerevisiae UFMGCB 11120 were selected for in vivo steps using mice challenged with S. Typhimurium. Both yeasts reached high faecal population levels when daily administered, but only R. mucilaginosa UFMGCB 18377 protected mice against Salmonella infection presenting a higher survival and reduced weight loss, bacterial translocation to the liver, sIgA intestinal levels, and intestinal and hepatic MPO and EPO activities. Our in vitro and in vivo results suggest that R. mucilaginosa UFMGCB 18377 presents probiotic potential and deserve further studies as candidate of probiotic by-products. In addition, this is the first screening study of yeasts isolated from Antarctic environments and of Rhodotorula genus for probiotic use.

Fungi of Antarctica, 2019

The biota of Antarctica lakes is constituted by simplified aquatic food webs characterised by low... more The biota of Antarctica lakes is constituted by simplified aquatic food webs characterised by low zooplankton biomass, absence of fish, and low floristic diversity (algae and aquatic mosses), but primarily encompassing microorganisms such as viruses, cyanobacteria, bacteria, archaea, and fungi. Among the microbial communities, fungi are widely spread in the different Antarctic lakes and, despite the extreme conditions of the region, show moderate diversity and richness with dominance of a few taxa. Endemic fungal species are found in the Antarctic lakes; however, the majority of fungi are characterised as cosmopolitan cold-adapted species that arrive as propagules from outside Antarctica and are adapted to disperse in the temporary or perennial water bodies, including saline and freshwater lakes. These fungi are subjected to freezing and melting cycles, low temperatures, and high incidence of UV radiation, mainly during the long periods of light in Austral summers. In contrast, in Austral winters, fungi are exposed to extreme freezing conditions. Additionally, in the lakes of Antarctica, fungi act as decomposers and interact with other organisms, such as parasites, or are in symbiotic associations, which consequently influence the lake food web dynamics. In Antarctica, cold-adapted cosmopolitan and psychrophilic fungi have the ability to grow, colonise substrates, and produce extracellular cold-active enzymes and other metabolites, which actively participate in the cycling of nutrients in lakes. In this chapter, we present the characteristics of different Antarctic lakes and shed light on various aspects of taxonomy, ecology, and potential applications of freshwater fungi from maritime and continental Antarctica.

Microbial Ecology, 2021

We assessed fungal diversity in deep-sea sediments obtained from different depths in the Southern... more We assessed fungal diversity in deep-sea sediments obtained from different depths in the Southern Ocean using the internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA by metabarcoding through high-throughput sequencing (HTS). We detected 655,991 DNA reads representing 263 fungal amplicon sequence variants (ASVs), dominated by Ascomycota , Basidiomycota , Mortierellomycota , Mucoromycota , Chytridiomycota and Rozellomycota , confirming that deep-sea sediments can represent a hotspot of fungal diversity in Antarctica. The community diversity detected included 17 dominant fungal ASVs, 62 intermediate and 213 rare. The dominant fungi included taxa of Mortierella , Penicillium , Cladosporium , Pseudogymnoascus , Phaeosphaeria and Torula . Despite the extreme conditions of the Southern Ocean benthos, the total fungal community detected in these marine sediments displayed high indices of diversity and richness, and moderate dominance, which varied between the different depths sampled. The highest diversity indices were obtained in sediments from 550 m and 250 m depths. Only 49 ASVs (18.63%) were detected at all the depths sampled, while 16 ASVs were detected only in the deepest sediment sampled at 1463 m. Based on sequence identities, the fungal community included some globally distributed taxa, primarily recorded otherwise from terrestrial environments, suggesting transport from these to deep marine sediments. The assigned taxa included symbionts, decomposers and plant-, animal- and human-pathogenic fungi, suggesting that deep-sea sediments host a complex fungal diversity, although metabarcoding does not itself confirm that living or viable organisms are present.

Scientific Reports, 2020

We assessed soil fungal diversity at two sites on Deception Island, South Shetland Islands, Antar... more We assessed soil fungal diversity at two sites on Deception Island, South Shetland Islands, Antarctica using DNA metabarcoding analysis. The first site was a relatively undisturbed area, and the second was much more heavily impacted by research and tourism. We detected 346 fungal amplicon sequence variants dominated by the phyla Ascomycota, Basidiomycota, Mortierellomycota and Chytridiomycota. We also detected taxa belonging to the rare phyla Mucoromycota and Rozellomycota, which have been difficult to detect in Antarctica by traditional isolation methods. Cladosporium sp., Pseudogymnoascus roseus, Leotiomycetes sp. 2, Penicillium sp., Mortierella sp. 1, Mortierella sp. 2, Pseudogymnoascus appendiculatus and Pseudogymnoascus sp. were the most dominant fungi. In addition, 440,153 of the total of 1,214,875 reads detected could be classified only at the level of Fungi. In both sampling areas the DNA of opportunistic, phytopathogenic and symbiotic fungi were detected, which might have b...

Springer Polar Sciences, 2019

Fungi are well known for their important roles in terrestrial ecosystems, but filamentous and yea... more Fungi are well known for their important roles in terrestrial ecosystems, but filamentous and yeast forms are also active components of microbial communities from marine ecosystems. Marine fungi are particularly abundant and relevant in coastal systems where they can be found in association with large organic substrata, like seaweeds. Antarctica is a rather unexplored region of the planet that is being influenced by strong and rapid climate change. In the past decade, several efforts have been made to get a thorough inventory of marine fungi from different environments, with a particular emphasis on those associated with the large communities of seaweeds that abound in littoral and infralittoral ecosystems. The algicolous fungal communities obtained were characterized by a few dominant species and a large number of singletons, as well as a balance among endemic, indigenous, and cold-adapted cosmopolitan species. The long-term monitoring of this balance and the dynamics of richness, dominance, and distributional patterns of these algicolous fungal communities is proposed to understand and model the influence of climate change on the maritime Antarctic biota. In addition, several fungal isolates from marine Antarctic environments have shown great potential as producers of bioactive natural products and enzymes and may represent attractive sources of biotechnological products.

Extremophiles, 2021

We evaluated the fungal diversity in two lakes on the South Shetland Islands, using DNA metabarco... more We evaluated the fungal diversity in two lakes on the South Shetland Islands, using DNA metabarcoding through high-throughput sequencing (HTS). A microcosm experiment was deployed for two consecutive years in lakes on Deception and King George islands to capture potential decomposer freshwater fungi. Analyses of the baits revealed 258,326 DNA reads distributed in 34 fungal taxa of the phyla Ascomycota , Basidiomycota , Mortierellomycota , Chytridiomycota and Rozellomycota . Tetracladium marchalianum , Tetracladium sp., Rozellomycota sp., Fungal sp. 1 and Fungal sp. 2 were the most common taxa detected. However, the majority of the communities comprised intermediate and rare taxa. Both fungal communities displayed moderate indices of diversity, richness and dominance. Only six taxa were detected in both lakes, including the most dominant T. marchalianum and Tetracladium sp. The high numbers of reads of the known aquatic saprotrophic hyphomycetes T. marchalianum and Tetracladium sp. in the baits suggest that these fungi may digest organic material in Antarctic lakes, releasing available carbon and nutrients to the other aquatic organisms present in the complex lake food web. Our data confirm that the use of cotton baits together with HTS approaches can be appropriate to study the diversity of resident freshwater fungi present in Antarctic lakes.

Extremophiles, 2020

In this study, we accessed culturable fungal assemblages present in the sediments of three lakes ... more In this study, we accessed culturable fungal assemblages present in the sediments of three lakes potentially impacted anthropogenically in the Fildes Peninsula, King George Island, Antarctica and identified 63 taxa. Cladosporium sp. 2, Pseudeurotium hygrophilum , and Pseudogymnoascus verrucosus were recovered from the sampled sediments of all lakes. High concentrations of metals and the lowest fungal diversity indices were detected in the sediments of the Central Lake, which can be influenced by human activities due to their proximity to research stations to those of the other two lakes, which were far from the Antarctic stations. At least one type of biological activity was demonstrated by 40 fungal extracts. Among these, P. hygrophilum , P. verrucosus , Penicillium glabrum , and Penicillium solitum demonstrated strong trypanocidal, herbicidal, and antifungal activities. Our results suggest that an increase of the anthropogenic activities in the region might have affected the microbial diversity and composition. In addition, the fungal diversity in these lakes may be a useful model to study the effect of anthropogenic activities in Antarctica. We isolated a diverse group of fungal taxa from Antarctic lake sediments, which have the potential to produce novel compounds for the both the medical and agriculture sectors.

Extremophiles, 2019

We accessed the culturable mycobiota present in marine sediments at different depths in Antarctic... more We accessed the culturable mycobiota present in marine sediments at different depths in Antarctica Ocean. Acremonium fusidioides, Penicillium allii-sativi, Penicillium chrysogenum, Penicillium palitans, Penicillium solitum, and Pseudogymnoascus verrucosus were identified. Penicillium allii-sativi was the dominant species. At least one isolate of each species was capable to present antifungal, trypanocidal, leishmanicidal, antimalarial, nematocidal, or herbicidal activities. Penicillium produced extracts with strong trypanocidal and antimalarial activities, and the extracts of P. solitum and P. chrysogenum demonstrated strong antimalarial activities. Acremonium fusidioides and P. verrucosus displayed strong selective herbicidal properties. The 1 H NMR signals for extracts of A. fusidioides, P. chrysogenum, and P. solitum indicated the presence of highly functionalized secondary metabolites, which may be responsible for the biological activities detected. In the deep marine Antarctic sediments, we detected fungal assemblages in which the Penicillium species were found to be dominant and demonstrated capabilities to survive and/or colonise that poly-extreme habitat. Penicillium being a polyextremophile Antarctic species, exhibited strong biological activities and the presence of aromatic compounds in its extracts may indicate that they are wild ancient strains with high genetic and biochemical potentials that enable them to produce bioactive compounds which can be researched in further studies and used in the chemotherapy of neglected tropical diseases as well as in agriculture.

Revista da Sociedade Brasileira de Medicina Tropical, 2019

Introduction: Administration of total parenteral nutrition (TPN) via catheters increases the risk... more Introduction: Administration of total parenteral nutrition (TPN) via catheters increases the risk for candidemia from Candida parapsilosis. Methods: C. parapsilosis sensu stricto blood isolates were evaluated for ability total biomass biofilm formation and morphogenesis in presence of glucose at TPN equivalent concentrations. Results: Biofilms were increased at high glucose concentrations (25-30%) compared to the control medium. Significant increase in filamentous forms was observed in cultures with 30% glucose. Conclusions: Biofilm formation by C. parapsilosis sensu stricto in hyperglycidic medium may contribute to its pathogenic potential for fungemia related to TPN catheters.

Brazilian Journal of Food Technology, 2015

Resumo Bacteriocinas são peptídeos antimicrobianos sintetizados nos ribossomos, tendo sido descri... more Resumo Bacteriocinas são peptídeos antimicrobianos sintetizados nos ribossomos, tendo sido descrita uma grande diversidade de bacteriocinas, as quais diferem entre si quanto a composição de aminoácidos, biossíntese, transporte e modo de ação. Nos alimentos, as bacteriocinas podem ser encontradas naturalmente como produtos da microbiota normal ou introduzida (cultura starter ou probióticos). Devido às suas aplicabilidades frente a organismos patogênicos contaminantes em alimentos, vários estudos têm sido publicados, tornando o uso destes peptídeos uma alternativa aos conservantes químicos tradicionais. Considerando-se as propriedades das bacteriocinas e sua potencial aplicação como bioconservadores de alimentos e alternativa aos antibióticos, o presente estudo busca acercar-se de uma visão geral das bacteriocinas quanto aos aspectos históricos, sistemas de classificação, biossíntese e transporte, modo de ação, abordando também algumas de suas aplicações na indústria de alimentos.

Journal of microbiology and biotechnology, Jan 24, 2016

In the current study, a total of 135 enterococci strains from different sources were searched for... more In the current study, a total of 135 enterococci strains from different sources were searched for the presence of enterocin-encoding genes entA, entP, entB, entL50A and entL50B. Enterocin genes occurred at different frequencies where entA was the most frequent, followed by entP and entB; entL50A and L50B were not detected. The frequency of genes occurring singly was higher than in multiple combinations. The 80 isolates that harbor at least one enterocin-encoding gene (denoted "Gene(+) strains") were screened for antimicrobial activity. Some 82.5% of the Gene(+) strains inhibited at least one of the indicator strains, besides, the isolates harboring multiple enterocin-encoding genes inhibited a larger number of indicators strains than isolates harboring a single gene. The indicator strains that exhibited growth inhibition include Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 6538, Listeria innocua CLIP 12612, Listeria monocytogenes CDC 4555, Enteroc...

Marine Microbial Bioremediation, 2021

Extremophiles : life under extreme conditions, 2021

We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north... more We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north-east Antarctic Peninsula using metabarcoding through high-throughput sequencing (HTS). A total of 640,902 fungal DNA reads were detected, which were assigned to 224 taxa of the phyla Ascomycota, Rozellomycota, Basidiomycota, Chytridiomycota and Mortierellomycota, in rank order of abundance. The most abundant genera were Pseudogymnoascus, Penicillium and Mortierella. However, a majority (423,508, 66%) of the reads, representing by 43 ASVs, could only be assigned at higher taxonomic levels and may represent taxa not currently included in the sequence databases used or be new or previously unreported taxa present in Antarctic lakes. The three lakes were characterized by high sequence diversity, richness, and moderate dominance indices. The ASVs were dominated by psychrotolerant and cosmopolitan cold-adapted Ascomycota, Basidiomycota and Mortierellomycota commonly reported in Antarctic envi...

Proceedings of the XII Latin American Congress on Food Microbiology and Hygiene, 2014