RESUMO
Antarctic soils generally have low temperatures and limited availability of liquid water and nutrients. However, animals can increase the nutrient availability of ice-free areas by transferring nutrients from marine to terrestrial ecosystems, mainly through their excreta. In this study, we employed shotgun metagenomics and population genome binning techniques to study the diversity of microbial communities in Antarctic soils impacted by marine pinnipeds and birds relative to soils with no evident animal presence. We obtained ~285,000 16S rRNA gene-carrying metagenomic reads representing ~60 phyla and 100 metagenome-assembled genomes (MAGs) representing eight phyla. Only nine of these 100 MAGs represented previously described species, revealing that these soils harbor extensive novel diversity. Proteobacteria, Actinobacteria, and Bacteroidetes were the most abundant phyla in all samples, with Rhodanobacter being one of the most abundant genera in the bird-impacted soils. Further, the relative abundance of genes related to denitrification was at least double in soils impacted by birds than soils without animal influence. These results advance our understanding of the microbial populations and their genes involved in nitrous oxide emissions in ice-free coastal Antarctic soils impacted by marine animals and reveal novel microbial diversity associated with these ecosystems.
Assuntos
Metagenoma , Microbiota , Animais , Regiões Antárticas , Metagenômica , Óxido Nitroso , RNA Ribossômico 16S , Solo , Microbiologia do SoloRESUMO
The strain KG01T was isolated from a soil sample from King George Island, Antarctica. Cells of KG01T are rod-shaped and motile by means of multiple polar flagella. The absence of arginine dihydrolase activity could be a key feature to readily distinguish KG01T from its closest phylogenetic relative species. The main fatty acids of the strain include summed feature 3 (C16â:â1 ω7c and/or C15â:â0 iso 2-OH), C16â:â0 and C18â:â1 ω7c. Phylogenetic analysis based on the 16S rRNA gene sequence and on a multilocus sequence analysis (MLSA) using housekeeping genes (16S rRNA, rpoB, rpoD, gyrB) were carried out. These analyses allowed us to include the strain within the Pseudomonas fluorescens group, presenting the highest similarity of multilocus sequence with Pseudomonas veronii LMG 17761T (96.67â%). The genome of KG01T was sequenced and in silico compared with genomes of the most closely related species of the P. fluorescens group. The average nucleotide identity (ANIb) and average amino acid identity (AAI) values of the species phylogenetically closest to KG01T were less than 95-96â%, threshold currently accepted to define strain as belonging to a bacterial species, the highest scores being those to Pseudomonas veronii LMG 17761T (87.98â%) and Pseudomonas marginalis ICMP 3553T (91.90â%). Therefore, the phenotypic and genotypic analyses results, allow us to propose that KG01T represents a member of a novel species of the genus Pseudomonas, for which the name Pseudomonas fildesensis is proposed, and KG01T (=CECT 9084T;=DSM 102036T) is established as the type strain .
Assuntos
Filogenia , Pseudomonas/classificação , Microbiologia do Solo , Regiões Antárticas , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Genes Bacterianos , Ilhas , Tipagem de Sequências Multilocus , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
The observational data described here was collected between 28 February 2011 and 30 November 2015. The data analysis and interpretation were published in the article "Surface radiation balance and weather conditions on a non-glaciated coastal area in the Antarctic region" [1]. An instrumented tower located on the non-glaciated coastal area of the of the Brazilian Antarctic Comandante Ferraz Station, at King George Island, Antarctic Peninsula was used. It was collected data of air temperature and relative humidity, wind speed and direction, barometric pressure, incident and reflected shortwave radiation, longwave radiation emitted by atmosphere and by surface, and net radiation with a sampling frequency of 0.1 Hz. The data was stored as 5-min averages and automatically transmitted to the Air-Sea Interaction Laboratory, at the University of São Paulo, Brazil. The dataset is hosted in the Mendeley repository.
RESUMO
Antarctic pristine environment is threatened by the presence of microplastics that occur in a variety of shapes and sizes, from fibers to irregular fragments. The aim of this study is to assess the abundance, distribution, and the characterization of the microfibers in zooplankton samples found in ocean waters in Admiralty Bay, Antarctica. The samples were collected at five points in Admiralty Bay during the XXIX Brazilian Antarctic Expedition in the austral summer of 2010-2011. A total of 603 microfibers were collected in 60 samples, with an average abundance of 2.40 (± 4.57) microfibers 100 m-3. Microfiber size ranging from ca. 10 to 22 µm in diameter of various lengths and colors (blue, red, black, and clear) was collected and characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Most of these microfibers were entangled in various different zooplankton species and were identified as polymers composed mostly by polyethyleneglycols, polyurethanes, polyethylene terephthalates, and polyamides. The presence of such microfibers may cause the loss of biodiversity in the Antarctic continent, and the results presented herein can contribute to a better understanding of the impact caused by them within the food chain and human health. Graphical Abstract á .