Project description:Desert microbial communities live in a pulsed ecosystem shaped by isolated and rare precipitation events. The Namib desert is one of the oldest continuously hyperarid ecosystems on Earth. In this study, surface microbial communities of open soils (without sheltering features like rocks, vegetation or biological soil crusts) are analysed. We designed an artificial rainfall experiment where a 7x7 (3.5 x 3.5 m) plot remained dry while an adjacent one received a 30 mm simulated rain. Samples were taken randomly in parallel from both plots at 10 min, 1 h, 3 h, 7 h, 24 h and 7 days after the watering moment. Duplicate libraries were generated from total (rRNA depleted) RNA and sequenced 2x150 bp in an Illumina Hiseq 4000 instrument.
Project description:In nature, bacteria reside in biofilms - multicellular differentiated communities held together by extracellular matrix. In this work, we identified a novel subpopulation essential for biofilm formation – mineral-forming cells in Bacillus subtilis biofilms. This subpopulation contains an intracellular calcium-accumulating niche, in which the formation of a calcium carbonate mineral is initiated. As the biofilm colony develops, this mineral grows in a controlled manner, forming a functional macrostructure that serves the entire community. Consistently, biofilm development is prevented by inhibition of calcium uptake. Taken together, our results provide a clear demonstration of the orchestrated production of calcite exoskeleton, critical to morphogenesis in simple prokaryotes. We expect future research exploring this newly discovered process to shed further light on mechanisms of bacterial development.
Project description:We developed a microbial catalytic concept and strategy to prepare calcium carbonate with micro/nanostructures on the surface of bioceramics to improve bone-forming bioactivity. It involves three processes: bacterial adhesion on biomaterials, production of carbonate assisted with bacteria, nucleation and growth of calcium carbonate nano-crystals on the surface of bioceramics. The microbially catalyzed biominerals exhibited relatively uniform micro/nanostructures on both 2D and 3D CaSiO3 bioceramics. The descriptive analysis of RNA-sequencing revealed that the topographic and chemical cues presented by microbially catalyzed micro/nanostructures could stimulate the biological processes including adhesion, proliferation and differentiation. The study offers a microbially catalytic concept and strategy of fabricating micro/nanostructured biomaterials for tissue regeneration.
Project description:The rate, timing, and mode of species dispersal is recognized as a key driver of the structure and function of communities of macroorganisms, and may be one ecological process that determines the diversity of microbiomes. Many previous studies have quantified the modes and mechanisms of bacterial motility using monocultures of a few model bacterial species. But most microbes live in multispecies microbial communities, where direct interactions between microbes may inhibit or facilitate dispersal through a number of physical (e.g., hydrodynamic) and biological (e.g., chemotaxis) mechanisms, which remain largely unexplored. Using cheese rinds as a model microbiome, we demonstrate that physical networks created by filamentous fungi can impact the extent of small-scale bacterial dispersal and can shape the composition of microbiomes. From the cheese rind of Saint Nectaire, we serendipitously observed the bacterium Serratia proteamaculans actively spreads on networks formed by the fungus Mucor. By experimentally recreating these pairwise interactions in the lab, we show that Serratia spreads on actively growing and previously established fungal networks. The extent of symbiotic dispersal is dependent on the fungal network: diffuse and fast-growing Mucor networks provide the greatest dispersal facilitation of the Serratia species, while dense and slow-growing Penicillium networks provide limited dispersal facilitation. Fungal-mediated dispersal occurs in closely related Serratia species isolated from other environments, suggesting that this bacterial-fungal interaction is widespread in nature. Both RNA-seq and transposon mutagenesis point to specific molecular mechanisms that play key roles in this bacterial-fungal interaction, including chitin utilization and flagellin biosynthesis. By manipulating the presence and type of fungal networks in multispecies communities, we provide the first evidence that fungal networks shape the composition of bacterial communities, with Mucor networks shifting experimental bacterial communities to complete dominance by motile Proteobacteria. Collectively, our work demonstrates that these strong biophysical interactions between bacterial and fungi can have community-level consequences and may be operating in many other microbiomes.
Project description:Microbially induced carbonate precipitation (MICP) refers to the biogeochemical process in which calcium carbonate is precipitated by altering the local geochemical environment (Mortensen et al. 2011). These alterations occur as a by-product of common microbial metabolic activities by increasing the local carbonate content as well as pH thereby saturating the solution in respect to carbonate. To better understand the microbial ecology of MICP on a community level in natural environments, we chose to evaluate microbial communities derived from travertine adjacent to Crystal Geyser (CG), Utah. CG is a cold-driven, CO2 rich geyser which is surrounded by colorful travertine that has been suggested to be generated through microbial processes. We used a cultivation-independent, multi-omics approach combined with geochemical measurements to investigate metabolic pathways and physiologies potentially involved in MICP at CG. We collected samples from the top 20 cm of travertine adjacent to Crystal Geyser, Utah in November 2019 and June 2021 (38.9384° N, 110.1354° W) wearing gloves at all times. We sampled 1 m away from the borehole (CG-1) and 10 m away from the borehole (CG-10). We preserved all collected samples in RNAlater-like solution (Menke et al., 2017, Front. Microbiol. 8) in a 1:10 sediment: RNAlater-like solution ratio as previously validated (Jensen et al. (2021, Micro. Spec. 2021, 9:2)
Project description:Amorphous calcium carbonate (ACC) is a non-crystalline form of calcium carbonate, which is composed of aggregated nano-size primary particles. Here, we wanted to evaluate how ACC affects gene expression in a human lung cancer cell line (A549).
2023-08-21 | GSE235316 | GEO
Project description:Fungal diversity in Antrctic rocks and soils
Project description:<p>Drought stress negatively impacts microbial activity, but the magnitude of stress responses are likely dependent on a diversity of below ground interactions. Populus trichocarpa individuals and no plant bulk soils were exposed to extended drought (~0.03% gravimetric water content (GWC) after 12d), re-wet, and a 12-d 'recovery' period to determine the effects of plant presence in mediating soil microbiome stability to water stress. Plant metabolomic analyses indicated that drought exposure increased host investment in C and N metabolic pathways (amino acids, fatty-acids, phenolic glycosides) regardless of recovery. Several metabolites positively correlated with root-associated microbial alpha diversity, but not those of soil communities. Soil bacterial community composition shifted with P. trichocarpa presence and with drought relative to irrigated controls, whereas soil fungal composition only shifted with plant presence. However, root fungal communities strongly shifted with drought, whereas root bacterial communities changed to a lesser degree. The proportion of bacterial water-stress opportunistic OTUs (enriched counts in drought) were high (~11%) at the end of drying phases, and maintained after re-wet, and recovery phases in bulk soils, but declined over time in soils with plants present. For root fungi opportunistic OTUs were high at the end of recovery in drought treatments (~17% abundance), although relatively not responsive in soils, particularly planted soils (< 0.5% abundance for sensitive or opportunistic). These data indicate that plants modulate soil and root associated microbial drought responses via tight plant-microbe linkages during extreme drought scenarios, but trajectories after extreme drought vary with plant habitat and microbial functional groups.</p>
Project description:The experiment was designed to test the interactions of Spartina alterniflora, its microbiome, and the interaction of the plant-microbe relationship with oil from the Deepwater Horizon oil spill (DWH). Total RNA was extracted from leaf and root microbiome of S. alterniflora in soils that were oiled in DWH oil spill with or without added oil, as well as those grown in unoiled soil with or without added oil. The work in its entirety characterizes the transport, fate and catabolic activities of bacterial communities in petroleum-polluted soils and within plant tissues.
Project description:Because of severe abiotic limitations, Antarctic soils represent simplified ecosystems, where microorganisms are the principle drivers of nutrient cycling. This relative simplicity makes these ecosystems particularly vulnerable to perturbations, like global warming, and the Antarctic Peninsula is among the most rapidly warming regions on the planet. However, the consequences of the ongoing warming of Antarctica on microorganisms and the processes they mediate are unknown. Here, using 16S rRNA gene pyrosequencing and qPCR, we report a number of highly consistent changes in microbial community structure and abundance across very disparate sub-Antarctic and Antarctic environments following three years of experimental field warming (+ 0.5-2°C). Specifically, we found significant increases in the abundance of fungi and bacteria and in the Alphaproteobacteria-to-Acidobacteria ratio. These alterations were linked to a significant increase in soil respiration. Furthermore, the shifts toward generalist or opportunistic bacterial communities following warming weakened the linkage between bacterial diversity and functional diversity. Warming also increased the abundance of some organisms related to the N-cycle, detected as an increase in the relative abundance of nitrogenase genes via GeoChip microarray analyses. Our results demonstrate that soil microorganisms across a range of sub-Antarctic and Antarctic environments can respond consistently and rapidly to increasing temperatures, thereby potentially disrupting soil functioning. We conducted in situ warming experiments for three years using open-top chambers (OTCs) at one sub-Antarctic (Falkland Islands, 52ºS) and two Antarctic locations (Signy and Anchorage Islands, 60ºS and 67ºS respectively) (see Supplementary Fig. 1 for a map). OTCs increased annual soil temperature by an average of 0.8°C (at a depth of 5 cm), resulting in 8-43% increase in positive-degree days annually and a decrease in freeze-thaw cycle frequency by an average of 15 cycles per year (8). At each location, we included densely vegetated and bare fell-field soils in the experimental design for a total of six environments. Densely vegetated and bare environments represent two contrasting environments for Antarctic soil microorganisms, with large differences in terms of C and N inputs to soils. Massively parallel pyrosequencing (Roche 454 GS FLX Titanium) of 16S rRNA gene amplicons was used to follow bacterial diversity and community composition [GenBank Accession Numbers: HM641909-HM744649], and functional gene microarrays (GeoChip 2.0)(11) were used to assess changes in functional gene distribution. Bacterial and fungal communities were also quantified using real-time PCR.