Project description:Metagenome data from soil samples were collected at 0 to 10cm deep from 2 avocado orchards in Channybearup, Western Australia, in 2024. Amplicon sequence variant (ASV) tables were constructed based on the DADA2 pipeline with default parameters.
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:The microorganisms that colonized in or on hosts play significant roles in regulating host’s immunological fitness and bioenergy production, thus controls the host’s response to stress or foreign stimuli. Since radiation typically causes a pro-inflammatory and bioenergy expensive condition, we speculate that the radiation could influence gut microbial compositions, thereof the host-microbe bidirectional relationship. Pertinent model included exposing the young adult mice to total body irradiation (TBI) at doses of 9.5Gy and 11Gy, respectively. Descending colon contents (DCC) were collected from non-irradiated mice (baseline control), and irradiated mice euthanized on days 1, 3 and 9 post-TBI. DCC’s 16s ribosomal DNAs were screened for bacterial taxonomic classification and bacterial abundance profile informed metagenome-specific biofunctions. A second aliquot of same DCC was screened for untargeted metabolomics assay to find most perturbed metabolite-enriched networks. Dose-independent temporal delay since TBI emerged as the primary factor explaining the increased richness of bacterial community and the diversity of metabolite landscape. Among the mice exposed to 11Gy TBI, an increased abundance of Firmicutes, an anti-inflammatory and efficient energy harvesting bacteria accompanied an increment of pro-inflammatory Deferribacteres. Systems evaluation of the functional networks linked to DCC’s metagenome and metabolite, respectively, suggested a diverging trend between host and DCC microbes in regulating the network clusters, such as lipid metabolism, bioenergy synthesis, particularly at the later time points post-11Gy TBI. This analysis potentially suggested a disrupted symbiotic relationship between the host and microbes when the host became moribund.