Diversity of Microbiomes Across a 13,000-Year-Old Amazon Sediment.

The microbiome is fundamental for understanding bacterial activities in sediments. However, only a limited number of studies have addressed the microbial diversity of Amazonian sediments. Here, we studied the microbiome of sediments from a 13,000-year BP core retrieved in a floodplain lake in Amazonia using metagenomics and biogeochemistry. Our aim was to evaluate the possible environmental influence over a river to a lake transition using a core sample. To this end, we sampled a core in the Airo Lake, a floodplain lake in the Negro River basin. The Negro River is the largest tributary of the Amazon River. The obtained core was divided into three strata: (i) surface, almost complete separation of the Airo Lake from the Negro River when the environment becomes more lentic with greater deposition of organic matter (black-colored sediment); (ii) transitional environment (reddish brown); and (iii) deep, environment with a tendency for greater past influence of the Negro River (brown color). The deepest sample possibly had the greatest influence of the Negro River as it represented the bottom of this river in the past, while the surface sample is the current Airo Lake bottom. In total, six metagenomes were obtained from the three different depth strata (total number of reads: 10.560.701; sequence length: 538 ± 24, mean ± standard deviation). The older (deeper) sediment strata contained a higher abundance of Burkholderia, Chitinophaga, Mucilaginibacter, and Geobacter, which represented ~ 25% of the metagenomic sequences. On the other hand, the more recent sediment strata had mainly Thermococcus, Termophilum, Sulfolobus, Archaeoglobus, and Methanosarcina (in total 11% of the metagenomic sequences). The sequence data were binned into metagenome-assembled genomes (MAGs). The majority of the obtained MAGs (n = 16) corresponded to unknown taxa, suggesting they may belong to new species. The older strata sediment microbiome was enriched with sulfur cycle genes, TCA cycle, YgfZ, and ATP-dependent proteolysis in bacteria. Meanwhile, serine-glyoxylate cycle, stress response genes, bacterial cell division, cell division-ribosomal stress protein cluster, and oxidative stress increased in the younger strata. Metal resistance and antimicrobial resistance genes were found across the entire core, including genes coding for fluoroquinolones, polymyxin, vancomycin, and multidrug resistance transporters. These findings depict the possible microbial diversity during the depositional past events and provided clues of the past microbial metabolism throughout time.

Vibrio fluminensis sp. nov. isolated from the skin of Southern Atlantic sharpnose-pufferfish (Canthigaster figueiredoi).

This manuscript provides the description of the bacterial strain A621T characterized by Gram negative motile rods, presenting green circular colonies on TCBS. It was obtained from the skin of the sharpnose pufferfish Canthigaster figueredoi (Tetraodontidae Family), collected in Arraial do Cabo, located in the Rio de Janeiro region, Brazil. Optimum growth occurs at 20-28 °C in the presence of 3% NaCl. The Genome sequence of the novel isolate consisted of 4.224 Mb, 4431 coding genes and G + C content of 44.5%. Genomic taxonomy analysis based on average amino acid (AAI), genome-to-genome-distance (GGDH) and phylogenetic reconstruction placed (A621T= CBAS 741T = CAIM 1945T = CCMR 150T) into a new species of the genus Vibrio (Vibrio fluminensis sp. nov). The genome of the novel species contains four gene clusters (~ 56.17 Kbp in total) coding for different types of bioactive compounds that hint to several possible ecological roles in the sharpnose pufferfish host.

Breviolum and Cladocopium Are Dominant Among Symbiodiniaceae of the Coral Holobiont Madracis decactis.

The scleractinian reef building coral Madracis decactis is a cosmopolitan species. Understanding host-symbiont associations is critical for assessing coral's habitat requirements and its response to environmental changes. In this study, we performed a fine grained phylogenetic analyses of Symbiodiniaceae associated with Madracis in two locations in the Southwest Atlantic Ocean (Abrolhos Bank and St. Peter and St. Paul Archipelago). Previous studies have argued that Madracis is a specialist coral, with colonies harboring a single symbiont from the genus Breviolum (formerly clade B). However, these previous studies have not precisely addressed if Madracis is colonized by several types of Symbiodiniaceae simultaneously or whether this coral is a specialist. The hypothesis that Madracis is a generalist coral host was evaluated in the present study. A total of 1.9 million reads of ITS2 nuclear ribosomal DNA were obtained by Illumina MiSeq sequencing. While Symbiodiniaceae ITS2 sequences between two sampling depths were almost entirely (62%) from the genus Breviolum (formerly clade B), shallow (10-15 m) populations in Abrolhos had a greater diversity of ITS2 sequences in comparison to deeper (25-35 m) populations of St. Peter and St. Paul Archipelago. Cladocopium (formerly clade C) and Symbiodinium (formerly clade A) were also found in Abrolhos. A single Madracis colony can host different symbiont types with > 30 Symbiodiniaceae ITS2-type profiles. Abrolhos corals presented a higher photosynthetic potential as a possible result of co-occurrence of multiple Symbiodiniaceae in a single coral colony. Multiple genera/clades of Symbiodiniaceae possibly confer coral hosts with broader environmental tolerance and ability to occupy diverse or changing habitats.

Genome sequence of Vibrio fluvialis 362.3 isolated from coral Mussismilia braziliensis reveals genes related to marine environment adaptation.

Vibrio fluvialis is a halophilic bacterium frequently found in estuarine and coastal waters environments. The strain 362.3 was isolated from Mussismilia braziliensis coral of Abrolhos Bank. In this study, to gain insights into the marine adaptation in V. fluvialis, we sequenced the genome of 362.3 strain, which comprised 4,607,294 bp with a G + C content of 50.2%. In silico analysis showed that V. fluvialis 362.2 encodes genes related to chitin catabolic pathway, iron metabolism, osmotic stress and membrane transport.

Vibrio tetraodonis sp. nov.: genomic insights on the secondary metabolites repertoire.

Description of a Gram-negative, motile, circular-shaped bacterial strain, designated A511T obtained from the skin of the pufferfish Sphoeroides spengleri (Family Tetraodontidae), collected in Arraial do Cabo, Brazil. Optimum growth occurs at 20-28 °C in the presence of 3% NaCl. The genome sequence of the novel isolate consisted of 4.36 Mb, 3,976 coding genes and G + C content of 42.5%. Genomic taxonomy analyses based on average amino acid (AAI), genome-to-genome-distance (GGDH) and phylogenetic reconstruction placed A511T (= CBAS 712T = CAIM 1939T) into a new species of the genus Vibrio (Vibrio tetraodonis sp. nov.). The genome of the novel species contains eight genes clusters (~ 183.9 Kbp in total) coding for different types of bioactive compounds that hint to several possible ecological roles in the pufferfish host.

Genomic and ecological attributes of marine bacteriophages encoding bacterial virulence genes.

BACKGROUND: Bacteriophages encode genes that modify bacterial functions during infection. The acquisition of phage-encoded virulence genes is a major mechanism for the rise of bacterial pathogens. In coral reefs, high bacterial density and lysogeny has been proposed to exacerbate reef decline through the transfer of phage-encoded virulence genes. However, the functions and distribution of these genes in phage virions on the reef remain unknown. RESULTS: Here, over 28,000 assembled viral genomes from the free viral community in Atlantic and Pacific Ocean coral reefs were queried against a curated database of virulence genes. The diversity of virulence genes encoded in the viral genomes was tested for relationships with host taxonomy and bacterial density in the environment. These analyses showed that bacterial density predicted the profile of virulence genes encoded by phages. The Shannon diversity of virulence-encoding phages was negatively related with bacterial density, leading to dominance of fewer genes at high bacterial abundances. A statistical learning analysis showed that reefs with high microbial density were enriched in viruses encoding genes enabling bacterial recognition and invasion of metazoan epithelium. Over 60% of phages could not have their hosts identified due to limitations of host prediction tools; for those which hosts were identified, host taxonomy was not an indicator of the presence of virulence genes. CONCLUSIONS: This study described bacterial virulence factors encoded in the genomes of bacteriophages at the community level. The results showed that the increase in microbial densities that occurs during coral reef degradation is associated with a change in the genomic repertoire of bacteriophages, specifically in the diversity and distribution of bacterial virulence genes. This suggests that phages are implicated in the rise of pathogens in disturbed marine ecosystems.

A new genomic taxonomy system for the Synechococcus collective.

Cyanobacteria of the genus Synechococcus are major contributors to global primary productivity and are found in a wide range of aquatic ecosystems. This Synechococcus collective (SC) is metabolically diverse, with some lineages thriving in polar and nutrient-rich locations and others in tropical or riverine waters. Although many studies have discussed the ecology and evolution of the SC, there is a paucity of knowledge on its taxonomic structure. Thus, we present a new taxonomic classification framework for the SC based on recent advances in microbial genomic taxonomy. Phylogenomic analyses of 1085 cyanobacterial genomes demonstrate that organisms classified as Synechococcus are polyphyletic at the order rank. The SC is classified into 15 genera, which are placed into five distinct orders within the phylum Cyanobacteria: (i) Synechococcales (Cyanobium, Inmanicoccus, Lacustricoccus gen. Nov., Parasynechococcus, Pseudosynechococcus, Regnicoccus, Synechospongium gen. nov., Synechococcus and Vulcanococcus); (ii) Cyanobacteriales (Limnothrix); (iii) Leptococcales (Brevicoccus and Leptococcus); (iv) Thermosynechococcales (Stenotopis and Thermosynechococcus) and (v) Neosynechococcales (Neosynechococcus). The newly proposed classification is consistent with habitat distribution patterns (seawater, freshwater, brackish and thermal environments) and reflects the ecological and evolutionary relationships of the SC.

Rapid screening of marine bacterial symbionts using MALDI-TOF MS.

Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) is a rapid, cost-effective and high-throughput method for bacteria characterization. However, most previous studies focused on clinical isolates. In this study, we evaluated the use of MALDI-TOF MS as a rapid screening tool for marine bacterial symbionts. A set of 255 isolates from different marine sources (corals, sponge, fish and seawater) was analyzed using cell lysates to obtain a rapid grouping. Cluster analysis of mass spectra and 16S rRNA showed 18 groups, including Vibrio, Bacillus, Pseudovibrio, Alteromonas and Ruegeria. MALDI-TOF distance similarity scores ≥ 60% and ≥ 70% correspond to ≥ 98.7% 16S rRNA gene sequence similarity and ≥ 95% pyrH gene sequence similarity, respectively. MALDI-TOF MS is a useful tool for Vibrio species groups' identification.

Ecogenomics of the Marine Benthic Filamentous Cyanobacterium Adonisia.

Turfs are among the major benthic components of reef systems worldwide. The nearly complete genome sequences, basic physiological characteristics, and phylogenomic reconstruction of two phycobiliprotein-rich filamentous cyanobacteria strains isolated from turf assemblages from the Abrolhos Bank (Brazil) are investigated. Both Adonisia turfae CCMR0081T (= CBAS 745T) and CCMR0082 contain approximately 8 Mbp in genome size and experiments identified that both strains exhibit chromatic acclimation. Whereas CCMR0081T exhibits chromatic acclimation type 3 (CA3) regulating both phycocyanin (PC) and phycoerythrin (PE), CCMR0082 strain exhibits chromatic acclimation type 2 (CA2), in correspondence with genes encoding specific photosensors and regulators for PC and PE. Furthermore, a high number and diversity of secondary metabolite synthesis gene clusters were identified in both genomes, and they were able to grow at high temperatures (28 °C, with scant growth at 30 °C). These characteristics provide insights into their widespread distribution in reef systems.

Enterovibrio baiacu sp. nov.

We report here the novel species to encompass the isolate A649T (=CBAS 716T = CBRVS P1061T) obtained from viscera of the healthy pufferfish Sphoeroides spengleri (Family Tetraodontidae). Genomic taxonomy analysis demonstrates that the novel strain A649T had < 95% average amino acid identity/average nucleotide identity (AAI/ANI) and < 70% similarity of genome-to-genome distance (GGDH) towards its closest neighbors which places A649T into a new Enterovibrio species (Enterovibrio baiacu sp nov.). In silico phenotyping disclosed several features that may be used to differentiate related Enterovibrio species. The nearly complete genome assembly of strain A649T consisted of 5.4 Mbp and 4826 coding genes.

Genome sequence of Shewanella corallii strain A687 isolated from pufferfish (Sphoeroides spengleri).

We present here the genome sequence of Shewanella corallii strain A687 isolated from pufferfish Sphoeroides spengleri (Family Tetraodontidae). The assembly consists of 5,215,037 bp and contains 284 contigs, with a G+C content of 50.3%.

Halomonas coralii sp. nov. Isolated from Mussismilia braziliensis.

We report here the novel species Halomonas coralii. The nearly complete genome of strain 362.1T consisted of 4.4 Mbp (3989 CDS; 66.3% GC). Genomic taxonomy analysis demonstrates that the novel strain has < 83% AAI and < 29% GGDH towards its closest neighbors.

Metagenomic Analysis of the Whole Gut Microbiota in Brazilian Termitidae Termites Cornitermes cumulans, Cyrilliotermes strictinasus, Syntermes dirus, Nasutitermes jaraguae, Nasutitermes aquilinus, Grigiotermes bequaerti, and Orthognathotermes mirim.

Although some previous studies have described the microbial diversity of termite in Brazil, the lack of studies about this subject is still evident. In the present study, we described by whole genome sequencing, the gut microbiota of seven species of termites (Termitidae) with different feeding habits from four Brazilian locations. For the litter species, the most abundant bacterial phylum was Firmicutes, where Cornitermes cumulans and Syntermes dirus (Syntermitinae) were identified. For the humus species, the most abundant bacterial phylum was Proteobacteria where three species were studied: Cyrilliotermes strictinasus (Syntermitinae), Grigiotermes bequaerti (Apicotermitinae), and Orthognathotermes mirim (Termitinae). For the wood termites, Firmicutes and Spirochaetes were the most abundant phyla, respectively, where two species were identified: Nasutitermes aquilinus and Nasutitermes jaraguae (Nasutitermitinae). The gut microbiota of all four examined subfamilies shared a conserved functional and carbohydrate-active enzyme profile and specialized in cellulose and chitin degradation. Taken together, these results provide insight into the partnerships between termite and microbes that permit the use of refractory energy sources.

Rhodoliths holobionts in a changing ocean: host-microbes interactions mediate coralline algae resilience under ocean acidification.

BACKGROUND: Life in the ocean will increasingly have to contend with a complex matrix of concurrent shifts in environmental properties that impact their physiology and control their life histories. Rhodoliths are coralline red algae (Corallinales, Rhodophyta) that are photosynthesizers, calcifiers, and ecosystem engineers and therefore represent important targets for ocean acidification (OA) research. Here, we exposed live rhodoliths to near-future OA conditions to investigate responses in their photosynthetic capacity, calcium carbonate production, and associated microbiome using carbon uptake, decalcification assays, and whole genome shotgun sequencing metagenomic analysis, respectively. The results from our live rhodolith assays were compared to similar manipulations on dead rhodolith (calcareous skeleton) biofilms and water column microbial communities, thereby enabling the assessment of host-microbiome interaction under climate-driven environmental perturbations. RESULTS: Under high pCO2 conditions, live rhodoliths exhibited positive physiological responses, i.e. increased photosynthetic activity, and no calcium carbonate biomass loss over time. Further, whereas the microbiome associated with live rhodoliths remained stable and resembled a healthy holobiont, the microbial community associated with the water column changed after exposure to elevated pCO2. CONCLUSIONS: Our results suggest that a tightly regulated microbial-host interaction, as evidenced by the stability of the rhodolith microbiome recorded here under OA-like conditions, is important for host resilience to environmental stress. This study extends the scarce comprehension of microbes associated with rhodolith beds and their reaction to increased pCO2, providing a more comprehensive approach to OA studies by assessing the host holobiont.

Microbial and Functional Biodiversity Patterns in Sponges that Accumulate Bromopyrrole Alkaloids Suggest Horizontal Gene Transfer of Halogenase Genes.

Marine sponge holobionts harbor complex microbial communities whose members may be the true producers of secondary metabolites accumulated by sponges. Bromopyrrole alkaloids constitute a typical class of secondary metabolites isolated from sponges that very often display biological activities. Bromine incorporation into secondary metabolites can be catalyzed by either halogenases or haloperoxidases. The diversity of the metagenomes of sponge holobiont species containing bromopyrrole alkaloids (Agelas spp. and Tedania brasiliensis) as well as holobionts devoid of bromopyrrole alkaloids spanning in a vast biogeographic region (approx. Seven thousand km) was studied. The origin and specificity of the detected halogenases was also investigated. The holobionts Agelas spp. and T. brasiliensis did not share microbial halogenases, suggesting a species-specific pattern. Bacteria of diverse phylogenetic origins encoding halogenase genes were found to be more abundant in bromopyrrole-containing sponges. The sponge holobionts (e.g., Agelas spp.) with the greatest number of sequences related to clustered, interspaced, short, palindromic repeats (CRISPRs) exhibited the fewest phage halogenases, suggesting a possible mechanism of protection from phage infection by the sponge host. This study highlights the potential of phages to transport halogenases horizontally across host sponges, particularly in more permissive holobiont hosts, such as Tedania spp.

Description of Alteromonas abrolhosensis sp. nov., isolated from sea water of Abrolhos Bank, Brazil.

Two Gram-negative, motile, aerobic bacteria isolated from waters of the Abrolhos Bank were classified through a whole genome-based taxonomy. Strains PEL67ET and PEL68C shared 99% 16S rRNA and dnaK sequence identity with Alteromonas marina SW-47T and Alteromonas macleodii ATCC 27126T. In silico DNA-DNA Hybridization, i.e. genome-to-genome distance (GGD), average amino acid identity (AAI) and average nucleotide identity (ANI) showed that PEL67ET and PEL68C had identity values between 33-36, 86-88 and 83-84%, and 85-86 and 83%, respectively, towards their close neighbors A. macleodii ATCC 27126T and A. marina SW-47T. The DNA G + C contents of PEL67ET and PEL68C were 44.5%. The phenotypic features that differentiate PEL67ET and PEL68C strains from their close neighbors were assimilation of galactose and activity of phosphatase, and lack of mannitol, maltose, acetate, xylose and glycerol assimilation and lack of lipase, α and ß-glucosidase activity. The new species Alteromonas abrolhosensis is proposed. The type strain is PEL67ET (= CBAS 610T = CAIM 1925T).

Metaproteomics reveals metabolic transitions between healthy and diseased stony coral Mussismilia braziliensis.

Infectious diseases such as white plague syndrome (WPS) and black band disease (BBD) have caused massive coral loss worldwide. We performed a metaproteomic study on the Abrolhos coral Mussismilia braziliensis to define the types of proteins expressed in healthy corals compared to WPS- and BBD-affected corals. A total of 6363 MS/MS spectra were identified as 361 different proteins. Healthy corals had a set of proteins that may be considered markers of holobiont homoeostasis, including tubulin, histone, Rab family, ribosomal, peridinin-chlorophyll a-binding protein, F0F1-type ATP synthase, alpha-iG protein, calmodulin and ADP-ribosylation factor. Cnidaria proteins found in healthy M. braziliensis were associated with Cnidaria-Symbiodinium endosymbiosis and included chaperones (hsp70, hsp90 and calreticulin), structural and membrane modelling proteins (actin) and proteins with functions related to intracellular vesicular traffic (Rab7 and ADP-ribosylation factor 1) and signal transduction (14-3-3 protein and calmodulin). WPS resulted in a clear shift in the predominance of proteins, from those related to aerobic nitrogen-fixing bacteria (i.e. Rhizobiales, Sphingomonadales and Actinomycetales) in healthy corals to those produced by facultative/anaerobic sulphate-reducing bacteria (i.e. Enterobacteriales, Alteromonadales, Clostridiales and Bacteroidetes) in WPS corals. BBD corals developed a diverse community dominated by cyanobacteria and sulphur cycle bacteria. Hsp60, hsp90 and adenosylhomocysteinase proteins were produced mainly by cyanobacteria in BBD corals, which is consistent with elevated oxidative stress in hydrogen sulphide- and cyanotoxin-rich environments. This study demonstrates the usefulness of metaproteomics for gaining better comprehension of coral metabolic status in health and disease, especially in reef systems such as the Abrolhos that are suffering from the increase in global and local threatening events.

Insights from genome of Clostridium butyricum INCQS635 reveal mechanisms to convert complex sugars for biofuel production.

Clostridium butyricum is widely used to produce organic solvents such as ethanol, butanol and acetone. We sequenced the entire genome of C. butyricum INCQS635 by using Ion Torrent technology. We found a high contribution of sequences assigned for carbohydrate subsystems (15-20 % of known sequences). Annotation based on protein-conserved domains revealed a higher diversity of glycoside hydrolases than previously found in C. acetobutylicum ATCC824 strain. More than 30 glycoside hydrolases (GH) families were found; families of GH involved in degradation of galactan, cellulose, starch and chitin were identified as most abundant (close to 50 % of all sequences assigned as GH) in C. butyricum INCQS635. KEGG metabolic pathways reconstruction allowed us to verify possible routes in the C. butyricum INCQS635 and C. acetobutylicum ATCC824 genomes. Metabolic pathways for ethanol synthesis are similar for both species, but alcohol dehydrogenase of C. butyricum INCQS635 and C. acetobutylicum ATCC824 was different. The genomic repertoire of C. butyricum is an important resource to underpin future studies towards improved solvents production.

Description of Endozoicomonas arenosclerae sp. nov. using a genomic taxonomy approach.

The taxonomic position of strains Ab112(T) (CBAS 572(T)) and Ab227_MC (CBAS 573) was evaluated by means of genomic taxonomy. These isolates represent the dominant flora cultured from the healthy marine sponge Arenosclera brasiliensis, endemic to Rio de Janeiro. Strains CBAS 572(T) and CBAS 573 shared >98 % 16S rRNA sequence identity with Endozoicomonas numazuensis and Endozoicomonas montiporae. In silico DNA-DNA Hybridization, i.e. genome-to-genome distance (GGD), amino acid identity (AAI) and average nucleotide identity (ANI) further showed that these strains had <70 %, at maximum 71.1 and 78 % of identity, respectively, to their closest neighbours E. numazuensis and E. montiporae. The DNA G+C content of CBAS 572(T) and CBAS 573 were 47.6 and 47.7 mol%, respectively. Phenotypic and chemotaxonomic features also allowed a separation from the type strains of their phylogenetic neighbours. Useful phenotypic features for discriminating CBAS 572(T) and CBAS 573 from E. numazuensis and E. montiporae species include C8 esterase, N-acetyl-ß-glucosaminidase, citric acid, uridine and siderophore. The species Endozoicomonas arenosclerae sp. nov. is proposed to harbour the new isolates. The type strain is CBAS 572(T) (=Ab112(T)).

Microbial and sponge loops modify fish production in phase-shifting coral reefs.

Shifts from coral to algae dominance of corals reefs have been correlated to fish biomass loss and increased microbial metabolism. Here we investigated reef benthic and planktonic primary production, benthic dissolved organic carbon (DOC) release and bacterial growth efficiency in the Abrolhos Bank, South Atlantic. Benthic DOC release rates are higher while water column bacterial growth efficiency is lower at impacted reefs. A trophic model based on the benthic and planktonic primary production was able to predict the observed relative fish biomass in healthy reefs. In contrast, in impacted reefs, the observed omnivorous fish biomass is higher, while that of the herbivorous/coralivorous fish is lower than predicted by the primary production-based model. Incorporating recycling of benthic-derived carbon in the model through microbial and sponge loops explains the difference and predicts the relative fish biomass in both reef types. Increased benthic carbon release rates and bacterial carbon metabolism, but decreased bacterial growth efficiency could lead to carbon losses through respiration and account for the uncoupling of benthic and fish production in phase-shifting reefs. Carbon recycling by microbial and sponge loops seems to promote an increase of small-bodied fish productivity in phase-shifting coral reefs.