Abstract Microorganisms in Antarctica are recognized for having crucial roles in ecosystems functioning and biogeochemical cycles. To explore the diversity and composition of microbial communities through different terrestrial and marine Antarctic habitats, we analyze 16S rRNA sequence datasets from fumarole and marine sediments, soil, snow and seawater environments. We obtained measures of alpha- and beta-diversities, as well as we have identified the core microbiome and the indicator microbial taxa of a particular habitat. Our results showed a unique microbial community structure according to each habitat, including specific taxa composing each microbiome. Marine sediments harbored the highest microbial diversity among the analyzed habitats. In the fumarole sediments, the core microbiome was composed mainly of thermophiles and hyperthermophilic Archaea, while in the majority of soil samples Archaea was absent. In the seawater samples, the core microbiome was mainly composed by cultured and uncultured orders usually identified on Antarctic pelagic ecosystems. Snow samples exhibited common taxa previously described for habitats of the Antarctic Peninsula, which suggests long-distance dispersal processes occurring from the Peninsula to the Continent. This study contributes as a baseline for further efforts on evaluating the microbial responses to environmental conditions and future changes. cycles S environments alpha betadiversities, betadiversities beta diversities, diversities beta-diversities habitat absent longdistance long distance Continent changes

Abstract In the Antarctic environment, yeasts are versatile eukaryotes that have shown wide dispersion in different substrates, producing active enzymes in extreme conditions, but their relevance in biotechnological applications is largely unknown. The aim of this study was to evaluate the production of extracellular hydrolases by yeasts isolated from Antarctic lichens and molecularly identify these isolates. From a total of 144 isolates on the screening, 109 (76%) produced at least one of the hydrolases tested, with most activities for proteases 59 (41%), cellulases 58 (40%), esterases 57 (39%), lipases 29 (20%), amylases 23 (16%) and pectinases 20 (14%). Among these isolates, 76 were identified, most belonged to the phylum Basidiomycota (n=73) with the dominance of Vishniacozyma victoriae (n=27), Cystobasidium alpinum (n=3), Mrakia niccombsii (n=3), Cystobasidium laryngis (n=2), Bannozyma yamatoana (n=2), Holtermanniella nyarrowii (n=2), and Glaciozyma martinii (n=2). This study is the first one reporting extracellular enzyme production by yeasts isolated from thallus of the species of Antarctic lichens Lecania brialmontii, Polycauliona candelaria, Usnea capillacea, Cladonia metacorallifera, and Polycauliona regalis. With these data, it’s possible to confirm lichens as a source of hydrolase-producing yeasts, reinforcing the potential of these microorganisms in bioprospecting studies of catalytic molecules from polar regions that may be useful in promising biotechnological applications.

A quantificação de compostos butílicos de estanho (BTs) em matrizes ambientais pode ser afetada pela ocorrência de interferentes encontrados em matrizes complexas tais como sedimentos e tecidos biológicos. O presente estudo investigou o efeito matriz em procedimentos analíticos para quantificação e especiação de BTs (TBT, DBT e MBT) em sedimentos e em dois tecidos (brânquias e fígado) de peixe, utilizando a técnica de cromatografia a gás com detecção fotométrica de chama pulsante (GC-PFPD). Diferentemente dos sedimentos avaliados, um efeito matriz significativo foi observado para os tecidos de peixe investigados, indicando que a quantificação de BTs deve ser realizada através da curva construída na matriz para evitar, dessa forma, erros de quantificação e redução da precisão analítica.

Butyltin (BTs) quantification in environmental matrices can be affected by interfering species found primarily in complex matrices, such as sediment and biota tissues. This study investigated matrix effects in analytical procedures for butyltin (TBT, DBT and MBT) quantification and speciation in sediments and in two fish tissues (gill and liver) by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis. Unlike sediment samples, tissues exhibited a significant matrix effect, thus, the quantification should be made by curve over matrix to avoid quantification errors and loss of analytical accuracy.

A maioria dos métodos para análise de esteróides em sedimentos marinhos é laboriosa, consome grandes volumes de solventes orgânicos (muitas vezes clorados) e produz grandes quantidades de material de descarte. Neste trabalho desenvolveu-se um método de extração com etanol e um "clean up" rápido, que oferece uma alternativa de menor custo e minimiza o uso de solventes clorados. As porcentagens de recuperação de esteróides (coprostanol, epicoprostanol, cholesterol, cholestanol, 5alfa-coprostanona and 5beta-coprostanona) ficaram na faixa de 70 a 93%, comparáveis às análises mais tradicionais. A eficiência do método foi avaliada através de material de referência e os resultados obtidos para coprostanol, colesterol e colestanol encontram-se próximos aos valores médios certificados e perfeitamente dentro dos valores aceitáveis. Os desvios-padrão relativos para triplicatas foram baixos (6-12%). Os testes indicaram que o "clean-up" simplificado (sem fracionamento) não produz interferência na quantificação dos esteróides fecais.

The majority of the analytical methods for steroids in marine sediments are laborious and time consuming and involve the use of large volumes of organic (frequently chlorinated) solvents. A method has been developed utilising ethanol extraction with a rapid alumina-ethanol elution clean up, providing an environmentally friendly and inexpensive alternative. Recoveries of steroids (coprostanol, epicoprostanol, cholesterol, cholestanol, 5alpha-coprostanone and 5beta-coprostanone) ranged from 70 to 93% and compared favourably with more traditional analyses. Analytical performance was tested through analysis of reference material and concentrations recorded for coprostanol, cholesterol and cholestanol were close to the mean certified values and were within acceptable values. Relative standard deviations from triplicate analyses were small (6-12%). These initial tests also indicate that the simplified clean up (without fractionation) is not subject to interference in the quantification of the selected faecal steroids.