Fábio Soares de Oliveira

Fungi associated with rocks of the Atacama Desert: taxonomy, distribution, diversity, ecology and bioprospection for bioactive compounds

This study assessed the diversity of cultivable rock-associated fungi from Atacama Desert. A total of 81 fungal isolates obtained were identified as 29 Ascomycota taxa by sequencing different regions of DNA. Cladosporium halotolerans, Penicillium chrysogenum and Penicillium cf. citrinum were the most frequent species, which occur at least in four different altitudes. The diversity and similarity indices ranged in the fungal communities across the latitudinal gradient. The Fisher-α index displayed the higher values for the fungal communities obtained from the siltstone and fine matrix of pyroclastic rocks with finer grain size, which are more degraded. A total of 23 fungal extracts displayed activity against the different targets screened. The extract of P. chrysogenum afforded the compounds α-linolenic acid and ergosterol endoperoxide, which were active against Cryptococcus neoformans and methicillin-resistance Staphylococcus aureus respectively. Our study represents the first report of a new habitat of fungi associated with rocks of the Atacama Desert and indicated the presence of interesting fungal community, including species related with saprobes, parasite/pathogen and mycotoxigenic taxa. The geological characteristics of the rocks, associated with the presence of rich resident/resilient fungal communities suggests that the rocks may provide a favourable microenvironment fungal colonization, survival and dispersal in extreme conditions.

A comparison of properties of clay minerals in isalteritic and in degraded facies

Abstract The mineralogical, geochemical and micromorphological features of an isalteritic clay facies, which originated from weathering of an anorthosite, were compared to those of clay facies derived from the degradation of a bauxite developed from the same rock. The isalteritic clay was formed by the hydrolytic alteration of plagioclase, whereas the degraded clays were formed by decomposition of gibbsite and neoformation of kaolinite. This resilification process resulted from the reintroduction of silica via the oscillation of the phreatic level and/or the decomposition of organic matter on the surface. The degradation process was gradual and yielded two different facies: (a) degraded clays with almost total decomposition of gibbsite, and (b) degraded clays with gibbsite nodules. Morphologically, the isalteritic clays differ from the degraded clays because they contain larger hexagonal and pseudo-hexagonal crystals. The degraded clays have more irregular crystal shapes, ranging from laths to anhedral shapes.

Cultivable fungi present in Antarctic soils: taxonomy, phylogeny, diversity, and bioprospecting of antiparasitic and herbicidal metabolites

Molecular biology techniques were used to identify 218 fungi from soil samples collected from four islands of Antarctica. These consisted of 22 taxa of 15 different genera belonging to the Zygomycota, Ascomycota, and Basidiomycota. Mortierella, Antarctomyces, Pseudogymnoascus, and Penicillium were the most frequently isolated genera and Penicillium tardochrysogenum, Penicillium verrucosus, Goffeauzyma gilvescens, and Mortierella sp. 2 the most abundant taxa. All fungal isolates were cultivated using solid-state fermentation to obtain their crude extracts. Pseudogymnoascus destructans, Mortierella parvispora, and Penicillium chrysogenum displayed antiparasitic activities, whilst extracts of P. destructans, Mortierella amoeboidea, Mortierella sp. 3, and P. tardochrysogenum showed herbicidal activities. Reported as pathogenic for bats, different isolates of P. destructans exhibited trypanocidal activities and herbicidal activity, and may be a source of bioactive molecules to be considered for chemotherapy against neglected tropical diseases. The abundant presence of P. destructans in soils of the four islands gives evidence supporting that soils in the Antarctic Peninsula constitute a natural source of strains of this genus, including some P. destructans strains that are phylogenetically close to those that infect bats in North America and Europe/Palearctic Asia.

Distribuição espacial de formações superficiais geneticamente associadas a rochas siliciclásticas – Planalto do Espinhaço Meridional (MG) - Brasil

A area de estudo que se situa na borda oeste do Planalto do Espinhaco Meridional, na qual predominam as rochas siliciclasticas que integram unidades geologicas diversas, observaram-se dois tipos distintos de padroes de distribuicao da formacao superficial, linear e zonal. Este trabalho objetiva analisar essa distribuicao espacial das formacoes superficiais de trecho do Planalto do Espinhaco Meridional localizado no alto curso do Rio Pardo Pequeno (MG), discutindo o papel exercido pela organizacao litoestrutural na espacialidade dessa cobertura pedologica. Para executar tal investigacao foram produzidos mapas de distribuicao espacial das formacoes superficiais, mapa de estrutura geologica, e perfis topograficos e geologicos. As formacoes superficiais verificadas na area de estudo apresentam uma distribuicao espacial essencialmente conduzida pelas caracteristicas do arcabouco estrutural e litologico da regiao. A distribuicao linear relaciona-se as feicoes estruturais, como: falhas, falhas de empurrao, alinhamentos, anticlinais e sinclinais. Ja as formacoes zonais sao influenciadas pelas diferencas entre a resistencia das diversas rochas aos processos intempericos. O estudo das caracteristicas das formacoes superficiais e suas associacoes com os aspectos litoestruturais sao essenciais para compreender a configuracao geomorfologica do alto curso do Rio Pardo Pequeno.

Brazil in the South Atlantic: The Fernando de Noronha and Trindade Archipelagos

The Brazilian oceanic islands are privileged places for studying unique landforms, evolved under an active tectonic setting, and humid to semi-arid climates of marine influence. The main landform aspects of the two main islands (Fernando de Noronha and Trindade) are presented, showing the importance of volcanic activity at hot spots, with older events in Noronha, resulting in extensive weathering and erosion of the less resistant rocks (tuffs, scoria), compared with prominent phonolite massive stocks, forming exhumed pinnacles and domes of structural resistance. In contrast, Late Quaternary volcanism at Trindade resulted in the preservation of younger volcanic features, such as caldera remains, volcanic platforms and slopes, lava and scoria fields, and dark-sand beaches formed by high contents of primary mineral such as magnetite. Storm beaches composed of large clasts (cobbles) are also found in both islands. Trindade and Noronha islands show polyphasic aeolian features at some coastal sectors, with sand dunes of bioclastic carbonates, with greater extension in Noronha compared with Trindade. Uplifted marine terraces are found in both islands, associated with former high sea levels. In contrast, the presence of submerged terraces at Noronha and Trindade is related to a combination of glacio-eustatic variations (low sea levels) and epeirogenic uplift. In Noronha (Rata Island), we can find a rare case of oceanic karst landscape developed on calcareous sandstone, with abundant lapiez and dissolution features. Also, ornithogenic soils are widespread, with great importance for paleoecological studies of former bird colonies in these isolated islands. The most prominent landforms are structural and tectonically controlled, and the erosion degree in Noronha advanced much farther than in Trindade, exhuming pre-existent volcanic necks and similar structures, forming a complex and impressive landform scenery. Trindade reveals unique, endemic landscapes formed by pure stands of arboreal ferns (Cyathea sp.), where deep organic soils developed. Fluvial erosion is very limited, but there is evidence of a former greater importance of run-off in Noronha and Trindade.