The Impact of Highly Weathered Oil from the Most Extensive Oil Spill in Tropical Oceans (Brazil) on the Microbiome of the Coral Mussismilia harttii.

In 2019, the largest oil spill ever recorded in tropical oceans in terms of extent occurred in Brazil. The oil from the spill was collected directly from the environment and used in an exposure experiment with the endangered reef-building coral Mussismilia harttii. The treatments of the experiment were control (without oil), 1% oil, 2.5% oil, and direct contact of coral with oil. The most abundant hydrocarbon in the seawater of the experiment was phenatrene, which is toxic to corals. However, overall, the concentration of PAHs was not very high. The analysis of the maximum photosynthetic capacity of Symbiodiniaceae dinoflagellates showed a small impact of oil on corals, mainly on the contact treatment. However, coral microbiomes were affected in all oil treatments, with the contact treatment showing the most pronounced impact. A greater number and abundance of stress-indicating and potentially pathogenic bacteria were found in all oil treatments. Finally, this highly weathered oil that had lain in the ocean for a long time was carrying potentially coral-pathogenic bacteria within the Vibrionaceae family and was able to transmit some of these bacteria to corals. Bacteria within Vibrionaceae are the main causes of disease in different species of corals and other marine organisms.

Mycobiome structure does not affect field litter decomposition in Eucalyptus and Acacia plantations.

Mixed tree plantations have been studied because of their potential to improve biomass production, ecosystem diversity, and soil quality. One example is a mixture of Eucalyptus and Acacia trees, which is a promising strategy to improve microbial diversity and nutrient cycling in soil. We examined how a mixture of these species may influence the biochemical attributes and fungal community associated with leaf litter, and the effects on litter decomposition. We studied the litter from pure and mixed plantations, evaluating the effects of plant material and incubation site on the mycobiome and decomposition rate using litterbags incubated in situ. Our central hypothesis was litter fungal community would change according to incubation site, and it would interfere in litter decomposition rate. Both the plant material and the incubation locale significantly affected the litter decomposition. The origin of the litter was the main modulator of the mycobiome, with distinct communities from one plant species to another. The community changed with the incubation time but the incubation site did not influence the mycobiome community. Our data showed that litter and soil did not share the main elements of the community. Contrary to our hypothesis, the microbial community structure and diversity lacked any association with the decomposition rate. The differences in the decomposition pattern are explained basically as a function of the exchange of nitrogen compounds between the litter.

Distribution of Anaerobic Hydrocarbon-Degrading Bacteria in Soils from King George Island, Maritime Antarctica.

Anaerobic diesel fuel Arctic (DFA) degradation has already been demonstrated in Antarctic soils. However, studies comparing the distribution of anaerobic bacterial groups and of anaerobic hydrocarbon-degrading bacteria in Antarctic soils containing different concentrations of DFA are scarce. In this study, functional genes were used to study the diversity and distribution of anaerobic hydrocarbon-degrading bacteria (bamA, assA, and bssA) and of sulfate-reducing bacteria (SRB-apsR) in highly, intermediate, and non-DFA-contaminated soils collected during the summers of 2009, 2010, and 2011 from King George Island, Antarctica. Signatures of bamA genes were detected in all soils analyzed, whereas bssA and assA were found in only 4 of 10 soils. The concentration of DFA was the main factor influencing the distribution of bamA-containing bacteria and of SRB in the analyzed soils, as shown by PCR-DGGE results. bamA sequences related to genes previously described in Desulfuromonas, Lautropia, Magnetospirillum, Sulfuritalea, Rhodovolum, Rhodomicrobium, Azoarcus, Geobacter, Ramlibacter, and Gemmatimonas genera were dominant in King George Island soils. Although DFA modulated the distribution of bamA-hosting bacteria, DFA concentration was not related to bamA abundance in the soils studied here. This result suggests that King George Island soils show functional redundancy for aromatic hydrocarbon degradation. The results obtained in this study support the hypothesis that specialized anaerobic hydrocarbon-degrading bacteria have been selected by hydrocarbon concentrations present in King George Island soils.

Bacterial and Archaeal Communities Variability Associated with Upwelling and Anthropogenic Pressures in the Protection Area of Arraial do Cabo (Cabo Frio region - RJ).

Upwelling systems contain a high diversity of pelagic microorganisms and their composition and activity are defined by factors like temperature and nutrient concentration. Denaturing gradient gel electrophoresis (DGGE) technique was used to verify the spatial and temporal genetic variability of Bacteria and Archaea in two stations of the Arraial do Cabo coastal region, one under upwelling pressure and another under anthropogenic pressure. In addition, biotic and abiotic variables were measured in surface and deep waters from three other stations between these stations. Six samplings were done during a year and adequately represented the degrees of upwelling and anthropogenic pressures to the system. Principal Component Analysis (PCA) showed negative correlations between the concentrations of ammonia and phosphorous with prokaryotic secondary production and the total heterotrophic bacteria. PCA also showed negative correlation between temperature and the abundance of prokaryotic cells. Bacterial and archaeal compositions were changeable as were the oceanographic conditions, and upwelling had a regional pressure while anthropogenic pressure was punctual. We suggest that the measurement of prokaryotic secondary production was associated with both Bacteria and Archaea activities, and that substrate availability and temperature determine nutrients cycling.

Evaluation of soil bioremediation techniques in an aged diesel spill at the Antarctic Peninsula.

Many areas on the Antarctic continent already suffer from the direct and indirect influences of human activities. The main cause of contamination is petroleum hydrocarbons because this compound is used as a source of energy at the many research stations around the continent. Thus, the current study aims to evaluate treatments for bioremediation (biostimulation, bioaugmentation, and bioaugmentation + biostimulation) using soils from around the Brazilian Antarctic Station "Comandante Ferraz" (EACF), King George Island, Antarctic Peninsula. The experiment lasted for 45 days, and at the end of this period, chemical and molecular analyses were performed. Those analyses included the quantification of carbon and nitrogen, denaturing gradient gel electrophoresis (DGGE) analysis (with gradient denaturation), real-time PCR, and quantification of total hydrocarbons and polyaromatics. Molecular tests evaluated changes in the profile and quantity of the rrs genes of archaea and bacteria and also the alkB gene. The influence of the treatments tested was directly related to the type of soil used. The work confirmed that despite the extreme conditions found in Antarctic soils, the bacterial strains degraded hydrocarbons and bioremediation treatments directly influenced the microbial communities present in these soils even in short periods. Although the majority of the previous studies demonstrate that the addition of fertilizer seems to be most effective at promoting bioremediation, our results show that for some conditions, autochthonous bioaugmentation (ABA) treatment is indicated. This work highlights the importance of understanding the processes of recovery of contaminated environments in polar regions because time is crucial to the soil recovery and to choosing the appropriate treatment.

Detection of proteases from Sporosarcina aquimarina and Algoriphagus antarcticus isolated from Antarctic soil.

Two psychrophilic bacterial samples were isolated from King George Island soil, in Antarctica. The phylogenetic analysis based on the 16S rRNA (rrs) gene led to the correlation with the closest related isolates as Sporosarcina aquimarina (99%) and Algoriphagus antarcticus (99%), with query coverage of 99% and 98%, respectively. The spent culture media from both isolates displayed proteolytic activities detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis containing gelatin as protein substrate. Under the employed conditions, S. aquimarina showed a 55 kDa protease with the best activity detected at pH 7.0 and at 27°C. A. antarcticus also showed a single extracellular protease, however its molecular mass was around 90kDa and its best activity was detected at pH 9.0 and at 37°C. The proteases from both isolates were inhibited by 1,10-phenanthroline and EDTA, two metalloprotease inhibitors. This is the first record of protease detection in both species, and our results may contribute to broaden the basic knowledge of proteases from the Antarctica environment and may help prospecting future biotechnological applications of these enzymes.