Active volcanoes in Antarctica contrast with their predominantly cold surroundings, resulting in environmental conditions capable of selecting for versatile and extremely diverse microbial communities. This is especially true on Deception Island, where geothermal, marine, and polar environments combine to create an extraordinary range of environmental conditions. Our main goal in this study was to understand how microbial community structure is shaped by gradients of temperature, salinity, and geochemistry in polar marine volcanoes. Thereby, we collected surface sediment samples associated with fumaroles and glaciers at two sites on Deception, with temperatures ranging from 0 to 98°C. Sequencing of the 16S rRNA gene was performed to assess the composition and diversity of Bacteria and Archaea. Our results revealed that Deception harbors a combination of taxonomic groups commonly found both in cold and geothermal environments of continental Antarctica, and also groups normally identified at deep and shallow-sea hydrothermal vents, such as hyperthermophilic archaea. We observed a clear separation in microbial community structure across environmental gradients, suggesting that microbial community structure is strongly niche driven on Deception. Bacterial community structure was significantly associated with temperature, pH, salinity, and chemical composition; in contrast, archaeal community structure was strongly associated only with temperature. Our work suggests that Deception represents a peculiar “open-air” laboratory to elucidate central questions regarding molecular adaptability, microbial evolution, and biogeography of extremophiles in polar regions.

Sup-sucking hemipterans host ancient heritable microorganisms that supplement their unbalanced diet with essential nutrients and have repeatedly been complemented or replaced by other microorganisms. These symbionts need to be reliably transmitted to subsequent generations through the reproductive system, and often they end up using the same route as the most ancient ones.

Microorganisms dominate most Antarctic marine ecosystems, in terms of biomass and taxonomic diversity, and play crucial role in ecosystem functioning due to their high metabolic plasticity. Admiralty Bay is the largest bay on King George Island (South Shetland Islands, Antarctic Peninsula) and a combination of hydro-oceanographic characteristics (bathymetry, sea ice and glacier melting, seasonal entrance of water masses, turbidity, vertical fluxes) create conditions favoring organic carbon deposition on the seafloor and microbial activities. We sampled surface sediments from 15 sites across Admiralty Bay (100–502 m total depth) and the adjacent North Bransfield Basin (693–1147 m), and used the amplicon 454-sequencing of 16S rRNA gene tags to compare the bacterial composition, diversity, and microbial community structure across environmental parameters (sediment grain size, pigments and organic nutrients) between the two areas. Marine sediments had a high abundance of heterotrophic Gammaproteobacteria (92.4% and 83.8% inside and outside the bay, respectively), followed by Alphaproteobacteria (2.5 and 5.5%), Firmicutes (1.5 and 1.6%), Bacteroidetes (1.1 and 1.7%), Deltaproteobacteria (0.8 and 2.5%) and Actinobacteria (0.7 and 1.3%). Differences in alpha-diversity and bacterial community structure were found between the two areas, reflecting the physical and chemical differences in the sediments, and the organic matter input.

In order to improve our understanding on the microbial complexity associated with Grade C/molar-incisor pattern periodontitis (GC/MIP), we surveyed the oral and fecal microbiomes of GC/MIP and compared to non-affected individuals (Control). Seven Afro-descendants with GC/MIP and seven age/race/gender-matched controls were evaluated. Biofilms from supra/subgingival sites (OB) and feces were collected and submitted to 16S rRNA sequencing. Aggregatibacter actinomycetemcomitans (Aa) JP2 clone genotyping and salivary nitrite levels were determined. Supragingival biofilm of GC/MIP presented greater abundance of opportunistic bacteria. Selenomonas was increased in subgingival healthy sites of GC/MIP compared to Control. Synergistetes and Spirochaetae were more abundant whereas Actinobacteria was reduced in OB of GC/MIP compared to controls. Aa abundance was 50 times higher in periodontal sites with PD≥ 4 mm of GC/MIP than in controls. GC/MIP oral microbiome was characterized by a reduction in commensals such as Kingella, Granulicatella, Haemophilus, Bergeyella, and Streptococcus and enrichment in periodontopathogens, especially Aa and sulfate reducing Deltaproteobacteria. The oral microbiome of the Aa JP2-like+ patient was phylogenetically distant from other GC/MIP individuals. GC/MIP presented a higher abundance of sulfidogenic bacteria in the feces, such as Desulfovibrio fairfieldensis, Erysipelothrix tonsillarum, and Peptostreptococcus anaerobius than controls. These preliminary data show that the dysbiosis of the microbiome in Afro-descendants with GC/MIP was not restricted to affected sites, but was also observed in supragingival and subgingival healthy sites, as well as in the feces. The understanding on differences of the microbiome between healthy and GC/MIP patients will help in developing strategies to improve and monitor periodontal treatment.

No abstract

Sap-sucking hemipterans host specialized, heritable microorganisms that supplement their unbalanced diet with essential nutrients. These microbes show unusual features that provide a unique perspective on the evolution of life but have not been systematically studied. Here, we combine microscopy with high-throughput sequencing to revisit 80-year-old reports on the diversity of symbiont transmission modes in a broadly distributed planthopper family Dictyopharidae. We show that in all species examined, the ancestral nutritional endosymbionts Sulcia and Vidania are complemented by co-primary symbionts, either Arsenophonus or Sodalis, acquired several times independently by different host lineages. Like in other obligate sap-feeders, the ancestral symbionts produce essential amino acids, whereas co-primary symbionts contribute to the biosynthesis of B vitamins. These symbionts reside within separate bacteriomes within the abdominal cavity, although in females, Vidania also occupies bacteriocytes in the rectal organ. Notably, the symbionts are transmitted from mothers to offspring in two alternative ways. In most examined species, all nutritional symbionts simultaneously infect the posterior end of the full-grown (vitellogenic) oocytes and next gather in their perivitelline space. In contrast, in other species, Sodalis colonizes the cytoplasm of the anterior pole of young (previtellogenic) oocytes forming a cluster separate from the "symbiont ball" formed by late-invading Sulcia and Vidania. Our data add to the evidence on frequent replacements of gammaproteobacterial symbionts combined with the relative functional stability of the nutritional functions during the evolution of sap-feeding insects, and show how newly-arriving microbes may utilize different strategies to establish long-term heritable symbiosis.

No abstract

Chagas disease is caused by the flagellate protozoan Trypanosoma cruzi. Cardiomyopathy and damage to gastrointestinal tissue are the main disease manifestations. There are data suggesting that the immune response to T. cruzi depends on the intestinal microbiota. We hypothesized that Chagas disease is associated with an altered gut microbiome and that these changes are related to the disease phenotype. The stool microbiome from 104 individuals, 73 with Chagas disease (30 with the cardiac, 11 with the digestive, and 32 with the indeterminate form), and 31 healthy controls was characterized using 16S rRNA amplification and sequencing. The QIIME (Quantitative Insights Into Microbial Ecology) platform was used to analyze the data. Alpha and beta diversity indexes did not indicate differences between the groups. However, the relative abundance of Verrucomicrobia, represented primarily by the genus Akkermansia, was significantly lower in the Chagas disease groups, especially the cardiac group, compared to the controls. Furthermore, differences in the relative abundances of Alistipes, Bilophila, and Dialister were observed between the groups. We conclude that T. cruzi infection results in changes in the gut microbiome that may play a role in the myocardial and intestinal inflammation seen in Chagas disease.