More Like this

1. Differential Patterns of Microbiota Recovery in Symbiotic and Aposymbiotic Corals following Antibiotic Disturbance

   https://doi.org/10.1128/mSystems.01086-20  

   Bent, Shavonna M. ; Miller, Carolyn A. ; Sharp, Koty H. ; Hansel, Colleen M. ; Apprill, Amy ( April 2021 , mSystems)

   Raina, Jean-Baptiste (Ed.)

   ABSTRACT Microbial relationships are critical to coral health, and changes in microbiomes are often exhibited following environmental disturbance. However, the dynamics of coral-microbial composition and external factors that govern coral microbiome assembly and response to disturbance remain largely uncharacterized. Here, we investigated how antibiotic-induced disturbance affects the coral mucus microbiota in the facultatively symbiotic temperate coral Astrangia poculata , which occurs naturally with high (symbiotic) or low (aposymbiotic) densities of the endosymbiotic dinoflagellate Breviolum psygmophilum . We also explored how differences in the mucus microbiome of natural and disturbed A. poculata colonies affected levels of extracellular superoxide, a reactive oxygen species thought to have both beneficial and detrimental effects on coral health. Using a bacterial and archaeal small-subunit (SSU) rRNA gene sequencing approach, we found that antibiotic exposure significantly altered the composition of the mucus microbiota but that it did not influence superoxide levels, suggesting that superoxide production in A. poculata is not influenced by the mucus microbiota. In antibiotic-treated A. poculata exposed to ambient seawater, mucus microbiota recovered to its initial state within 2 weeks following exposure, and six bacterial taxa played a prominent role in this reassembly. Microbial composition among symbiotic colonies was more similar throughout the 2-weekmore »recovery period than that among aposymbiotic colonies, whose microbiota exhibited significantly more interindividual variability after antibiotic treatment and during recovery. This work suggests that the A. poculata mucus microbiome can rapidly reestablish itself and that the presence of B. psygmophilum , perhaps by supplying nutrients, photosynthate, or other signaling molecules, exerts influence on this process. IMPORTANCE Corals are animals whose health is often maintained by symbiotic microalgae and other microorganisms, yet they are highly susceptible to environmental-related disturbances. Here, we used a known disruptor, antibiotics, to understand how the coral mucus microbial community reassembles itself following disturbance. We show that the Astrangia poculata microbiome can recover from this disturbance and that individuals with algal symbionts reestablish their microbiomes in a more consistent manner compared to corals lacking symbionts. This work is important because it suggests that this coral may be able to recover its mucus microbiome following disturbance, it identifies specific microbes that may be important to reassembly, and it demonstrates that algal symbionts may play a previously undocumented role in microbial recovery and resilience to environmental change.« less
2. Effects of tidal influence on the structure and function of prokaryotic communities in the sediments of a pristine Brazilian mangrove

   https://doi.org/10.5194/bg-18-2259-2021  

   de Santana, Carolina Oliveira ; Spealman, Pieter ; Melo, Vânia Maria ; Gresham, David ; de Jesus, Taíse Bomfim ; Chinalia, Fabio Alexandre ( January 2021 , Biogeosciences)

   Abstract. Mangrove forests are ecosystems that constitute a large portion of the world's coastline and span tidal zones below, between, and above thewaterline, and the ecosystem as a whole is defined by the health of these tidal microhabitats. However, we are only beginning to understand tidal-zone microbial biodiversity and the role of these microbiomes in nutrient cycling. While extensive research has characterized microbiomes inpristine vs. anthropogenically impacted mangroves, these have, largely, overlooked differences in tidal microhabitats (sublittoral, intertidal, andsupralittoral). Unfortunately, the small number of studies that have sought to characterize mangrove tidal zones have occurred in impacted biomes,making interpretation of the results difficult. Here, we characterized prokaryotic populations and their involvement in nutrient cycling across thetidal zones of a pristine mangrove within a Brazilian Environmental Protection Area of the Atlantic Forest. We hypothesized that the tidal zones inpristine mangroves are distinct microhabitats, which we defined as distinct regions that present spatial variations in the water regime and otherenvironmental factors, and as such, these are composed of different prokaryotic communities with distinct functional profiles. Samples werecollected in triplicate from zones below, between, and above the tidal waterline. Using 16S ribosomal RNA (rRNA) gene amplicon sequencing, we found distinctprokaryotic communities with significantlymore »diverse nutrient-cycling functions, as well as specific taxa with varying contributions to functionalabundances between zones. Where previous research from anthropogenically impacted mangroves found the intertidal zone to have high prokaryoticdiversity and be functionally enriched in nitrogen cycling, we find that the intertidal zone from pristine mangroves has the lowest diversity and nofunctional enrichment, relative to the other tidal zones. The main bacterial phyla in all samples were Firmicutes, Proteobacteria,and Chloroflexi while the main archaeal phyla were Crenarchaeota and Thaumarchaeota. Our results differ slightly fromother studies where Proteobacteria is the main phyla in mangrove sediments and Firmicutes makes up only a small percentage ofthe communities. Salinity and organic matter were the most relevant environmental factors influencing these communities. Bacillaceae wasthe most abundant family at each tidal zone and showed potential to drive a large proportion of the cycling of carbon, nitrogen, phosphorus, andsulfur. Our findings suggest that some aspects of mangrove tidal zonation may be compromised by human activity, especially in the intertidal zone.« less
3. Long-term warming in a Mediterranean-type grassland affects soil bacterial functional potential but not bacterial taxonomic composition

   https://doi.org/10.1038/s41522-021-00187-7  

   Gao, Ying ; Ding, Junjun ; Yuan, Mengting ; Chiariello, Nona ; Docherty, Kathryn ; Field, Chris ; Gao, Qun ; Gu, Baohua ; Gutknecht, Jessica ; Hungate, Bruce A. ; et al ( February 2021 , npj Biofilms and Microbiomes)

   Climate warming is known to impact ecosystem composition and functioning. However, it remains largely unclear how soil microbial communities respond to long-term, moderate warming. In this study, we used Illumina sequencing and microarrays (GeoChip 5.0) to analyze taxonomic and functional gene compositions of the soil microbial community after 14 years of warming (at 0.8–1.0 °C for 10 years and then 1.5–2.0 °C for 4 years) in a Californian grassland. Long-term warming had no detectable effect on the taxonomic composition of soil bacterial community, nor on any plant or abiotic soil variables. In contrast, functional gene compositions differed between warming and control for bacterial, archaeal, and fungal communities. Functional genes associated with labile carbon (C) degradation increased in relative abundance in the warming treatment, whereas those associated with recalcitrant C degradation decreased. A number of functional genes associated with nitrogen (N) cycling (e.g., denitrifying genes encoding nitrate-, nitrite-, and nitrous oxidereductases) decreased, whereasnifHgene encoding nitrogenase increased in the warming treatment. These results suggest that microbial functional potentials are more sensitive to long-term moderate warming than the taxonomic composition of microbial community.
4. Thermal Stress Interacts With Surgeonfish Feces to Increase Coral Susceptibility to Dysbiosis and Reduce Tissue Regeneration

   https://doi.org/10.3389/fmicb.2021.620458  

   Ezzat, Leïla ; Merolla, Sarah ; Clements, Cody S. ; Munsterman, Katrina S. ; Landfield, Kaitlyn ; Stensrud, Colton ; Schmeltzer, Emily R. ; Burkepile, Deron E. ; Vega Thurber, Rebecca ( March 2021 , Frontiers in Microbiology)

   Dysbiosis of coral microbiomes results from various biotic and environmental stressors, including interactions with important reef fishes which may act as vectors of opportunistic microbes via deposition of fecal material. Additionally, elevated sea surface temperatures have direct effects on coral microbiomes by promoting growth and virulence of opportunists and putative pathogens, thereby altering host immunity and health. However, interactions between these biotic and abiotic factors have yet to be evaluated. Here, we used a factorial experiment to investigate the combined effects of fecal pellet deposition by the widely distributed surgeonfish Ctenochaetus striatus and elevated sea surface temperatures on microbiomes associated with the reef-building coral Porites lobata . Our results showed that regardless of temperature, exposure of P. lobata to C. striatus feces increased alpha diversity, dispersion, and lead to a shift in microbial community composition – all indicative of microbial dysbiosis. Although elevated temperature did not result in significant changes in alpha and beta diversity, we noted an increasing number of differentially abundant taxa in corals exposed to both feces and thermal stress within the first 48h of the experiment. These included opportunistic microbial lineages and taxa closely related to potential coral pathogens (i.e., Vibrio vulnificus , Photobacterium rosenbergii ).more »Some of these taxa were absent in controls but present in surgeonfish feces under both temperature regimes, suggesting mechanisms of microbial transmission and/or enrichment from fish feces to corals. Importantly, the impact to coral microbiomes by fish feces under higher temperatures appeared to inhibit wound healing in corals, as percentages of tissue recovery at the site of feces deposition were lower at 30°C compared to 26°C. Lower percentages of tissue recovery were associated with greater relative abundance of several bacterial lineages, with some of them found in surgeonfish feces (i.e., Rhodobacteraceae, Bdellovibrionaceae, Crocinitomicaceae). Our findings suggest that fish feces interact with elevated sea surface temperatures to favor microbial opportunism and enhance dysbiosis susceptibility in P. lobata . As the frequency and duration of thermal stress related events increase, the ability of coral microbiomes to recover from biotic stressors such as deposition of fish feces may be greatly affected, ultimately compromising coral health and resilience.« less
5. Defining the Sphagnum Core Microbiome across the North American Continent Reveals a Central Role for Diazotrophic Methanotrophs in the Nitrogen and Carbon Cycles of Boreal Peatland Ecosystems

   https://doi.org/10.1128/mbio.03714-21  

   Kolton, Max ; Weston, David J. ; Mayali, Xavier ; Weber, Peter K. ; McFarlane, Karis J. ; Pett-Ridge, Jennifer ; Somoza, Mark M. ; Lietard, Jory ; Glass, Jennifer B. ; Lilleskov, Erik A. ; et al ( February 2022 , mBio)

   Martiny, Jennifer B. (Ed.)

   ABSTRACT Peat mosses of the genus Sphagnum are ecosystem engineers that frequently predominate over photosynthetic production in boreal peatlands. Sphagnum spp. host diverse microbial communities capable of nitrogen fixation (diazotrophy) and methane oxidation (methanotrophy), thereby potentially supporting plant growth under severely nutrient-limited conditions. Moreover, diazotrophic methanotrophs represent a possible “missing link” between the carbon and nitrogen cycles, but the functional contributions of the Sphagnum -associated microbiome remain in question. A combination of metagenomics, metatranscriptomics, and dual-isotope incorporation assays was applied to investigate Sphagnum microbiome community composition across the North American continent and provide empirical evidence for diazotrophic methanotrophy in Sphagnum -dominated ecosystems. Remarkably consistent prokaryotic communities were detected in over 250 Sphagnum SSU rRNA libraries from peatlands across the United States (5 states, 17 bog/fen sites, 18 Sphagnum species), with 12 genera of the core microbiome comprising 60% of the relative microbial abundance. Additionally, nitrogenase ( nifH ) and SSU rRNA gene amplicon analysis revealed that nitrogen-fixing populations made up nearly 15% of the prokaryotic communities, predominated by Nostocales cyanobacteria and Rhizobiales methanotrophs. While cyanobacteria comprised the vast majority (>95%) of diazotrophs detected in amplicon and metagenome analyses, obligate methanotrophs of the genus Methyloferula (order Rhizobiales ) accounted for one-quartermore »of transcribed nifH genes. Furthermore, in dual-isotope tracer experiments, members of the Rhizobiales showed substantial incorporation of 13 CH 4 and 15 N 2 isotopes into their rRNA. Our study characterizes the core Sphagnum microbiome across large spatial scales and indicates that diazotrophic methanotrophs, here defined as obligate methanotrophs of the rare biosphere ( Methyloferula spp. of the Rhizobiales ) that also carry out diazotrophy, play a keystone role in coupling of the carbon and nitrogen cycles in nutrient-poor peatlands. IMPORTANCE Nitrogen availability frequently limits photosynthetic production in Sphagnum moss-dominated high-latitude peatlands, which are crucial carbon-sequestering ecosystems at risk to climate change effects. It has been previously suggested that microbial methane-fueled fixation of atmospheric nitrogen (N 2 ) may occur in these ecosystems, but this process and the organisms involved are largely uncharacterized. A combination of omics (DNA and RNA characterization) and dual-isotope incorporation approaches illuminated the functional diversity of Sphagnum -associated microbiomes and defined 12 bacterial genera in its core microbiome at the continental scale. Moreover, obligate diazotrophic methanotrophs showed high nitrogen fixation gene expression levels and incorporated a substantial amount of atmospheric nitrogen and methane-driven carbon into their biomass. Thus, these results point to a central role for members of the rare biosphere in Sphagnum microbiomes as keystone species that couple nitrogen fixation to methane oxidation in nutrient-poor peatlands.« less