FEMS microbiology ecology最新文献

Recent exceptionally hot and dry summers provoked massive bark beetle outbreaks in German forests, which killed many conifers, forcing to clear-cut complete non-mature stands. The importance of fungi in ecosystems in particular in association with trees is widely recognized, but the ecology of how insect infestations of trees affect their mycobiomes remains poorly understood. Using Illumina MiSeq sequencing, we investigated fungal communities in soil, litter, and stem wood at early and late stages of bark beetle infestation in a Norway spruce [Picea abies (L.) Karst] stand in Central Germany. Fungal diversity decreased from soil to wood, with the highest proportion of unknown fungi in stem wood. Lifestyles, particularly of those fungi associated with stem wood, clearly changed depending on the infestation stage. The answer of tree-associated fungi to beetle infestation was characterized by an increasing community dissimilarity among all three habitats, i.e. it concerned not only the above-ground fungal communities directly connected to the tree. Our study, thus, pinpoints the cascading effects of tree infestations by bark beetles and subsequent tree diebacks on the proximate and distant mycobiomes of the plant soil system, which should be entirely considered to tackle the effects of environmental events on tree health.

The microbiome of Saccharina latissima, an important brown macroalgal species in Europe, significantly influences its health, fitness, and pathogen resistance. Yet, comprehensive studies on the diversity and function of microbial communities (bacteria, eukaryotes, and fungi) associated with this species are lacking. Using metabarcoding, we investigated the epimicrobiota of S. latissima and correlated microbial diversity with metabolomic patterns (liquid chromatography coupled to tandem mass spectrometry). Specific epibacterial and eukaryotic communities inhabit the S. latissima surface, alongside a core microbiota, while fungal communities show lower and more heterogeneous diversity. Metabolomic analysis revealed a large diversity of mass features, including putatively annotated fatty acids, amino derivatives, amino acids, and naphthofurans. Multiple-factor analysis linked microbial diversity with surface metabolome variations, driven mainly by fungi and bacteria. Two taxa groups were identified: one associated with bacterial consortia and the other with fungal consortia, each correlated with specific metabolites. This study demonstrated a core bacterial and eukaryotic microbiota associated with a core metabolome and highlighted interindividual variations. Annotating the surface metabolome using Natural Products databases suggested numerous metabolites potentially involved in interspecies chemical interactions. Our findings establish a link between microbial community structure and function, identifying two microbial consortia potentially involved in the chemical defense of S. latissima.

Studies have suggested that reduced nutrient availability enhances microbial diversity around plant roots, positively impacting plant productivity. However, the specific contributions of rhizosphere microbiomes in nutrient-poor environments still need to be better understood. This study investigates tomato (Solanum lycopersicum L.) root microbiome under low-nutrient conditions. Plants were grown in hydroponics with soil-derived microbial community inoculations. We hypothesized that nutrient limitation would increase the selection of beneficial bacterial communities, compensating for nutrient deficiencies. We identified 12 294 operational taxonomic units across treatments and controls using 16S rRNA gene sequencing. Increased plant biomass was observed in treatments compared to controls, suggesting a role for the microbiome in mitigating nutrient limitations. The relative abundance of genera such as Luteolibacter and Sphingopyxis relative abundance correlated with plant phenotypic traits (P ≤ .05), and their presence was further validated using shotgun metagenomics. We annotated 722 677 protein families and calculated a core set of 48 116 protein families shared across all treatments and assigned them into bacteria (93.7%) and eukaryota (6.2%). Within the core bacterial metagenome, we identified protein families associated with pathways involved in positive plant interactions like the nitrogen fixation. Limited nutrient availability enhanced plant productivity under controlled conditions, offering a path to reduce fertilizer use in agriculture.

Phytoplankton play a pivotal role as the primary producers in polar marine ecosystems. Despite evidence suggesting that production rates and loss factors vary from year to year, and thus drive dynamic ecosystem functioning, interannual comparisons remain sparse. In this study, we examined viral lysis and microzooplankton grazing rates on Antarctic phytoplankton during two productive seasons and compared them with published data from a previous year. Higher rates of phytoplankton gross growth and total mortality during the warmer productive season suggest global warming induced increases in the magnitude of ecosystem carbon flow. Viral lysis rates appear to be relatively independent of average seasonal temperatures, whereas grazing rates were lower during the colder productive seasons (average temperature <0°C). This resulted in a greater relative impact of viral lysis on phytoplankton mortality, particularly pronounced during periods of phytoplankton accumulation. The interannual variations in phytoplankton fate are likely due to a stronger coupling between rates of viral infection and phytoplankton growth compared with grazing. Our results emphasize the importance of monitoring rates of viral lysis, specifically in combination with the size and taxonomy of the phytoplankton community. Collectively these factors determine the relative significance of the different carbon fates, and hence the ocean's efficacy as a carbon sink.

Reef fishes exhibit enormous biodiversity within a highly interactive ecosystem. Relatively little is known about the diversity and evolution of microbial species associated with reef fish, even though this may provide valuable insights into the factors that shape microbial communities. Through metatranscriptomic sequencing, we characterized the viruses, bacteria, and single-celled eukaryotes from 126 reef fish species inhabiting Lizard Island and Orpheus Island on the Great Barrier Reef, Australia. We assessed whether microbial communities differed between islands that are separated by 450 km, and to what extent fish viruses emerge in new hosts. Despite strong ecological interactions within the species-rich reef environment, and the presence of the same families of viruses on both islands, there was minimal evidence for the presence of individual viruses shared among fish species, reflecting low levels of cross-species transmission. Among bacteria, we identified the opportunistic bacterial pathogen Photobacterium damselae in apparently healthy cardinalfish species from both islands, indicating that these fish species are natural reservoirs. These data suggest that reef fishes have microbial-host associations that arose prior to the formation of the Great Barrier Reef, likely leading to strong host barriers to cross-species transmission and hence infectious disease emergence.

Phytophagous insects engage in symbiotic relationships with bacteria that contribute to digestion, nutrient supplementation, and development of the host. The analysis of shield bug microbiomes has been mainly focused on the gut intestinal tract predominantly colonized by Pantoea symbionts and other microbial community members in the gut or other organs have hardly been investigated. In this study, we reveal that the Southern green shield bug Nezara viridula harbours a Sodalis symbiont in several organs, with a notable prevalence in salivary glands, and anterior regions of the midgut. Removing external egg microbiota via sterilization profoundly impacted insect viability but did not disrupt the vertical transmission of Sodalis and Pantoea symbionts. Based on the dominance of Sodalis in testes, we deduce that N. viridula males could be involved in symbiont vertical transmission. Genomic analyses comparing Sodalis species revealed that Sodalis sp. Nvir shares characteristics with both free-living and obligate insect-associated Sodalis spp. Sodalis sp. Nvir also displays genome instability typical of endosymbiont lineages, which suggests ongoing speciation to an obligate endosymbiont. Together, our study reveals that shield bugs harbour unrecognized symbionts that might be paternally transmitted.

Vertebrate nasal microbiota (NM) plays a key role regulating host olfaction, immunity, neuronal differentiation, and structuring the epithelium. However, little is known in fish. This study provides the first comprehensive analysis of the NM in two marine fish species, the European seabass and the Atlantic cod. Given its direct environmental exposure, fish NM is likely influenced by seawater fluctuations. We analysed the community structure, specificity regarding seawater, and interindividual variability of 32-38 fish reared under ambient conditions. Additionally, we conducted an experiment to investigate the influence of acidification and a simplified heatwave on cod NM (three fish per replicate). High-throughput 16S rRNA sequencing revealed species-specific NM communities at the genus-level with Stenotrophomonas and Ralstonia dominating seabass and cod NM, respectively. This suggests potential habitat- or physiology-related adaptations. The most abundant bacterial genera in seabass NM were also present in seawater, suggesting environmental acquisition. Alpha diversity was highest in Brest seabass NM and variability greatest in Tromsø cod NM. Simulated climate change-related scenarios did not significantly alter cod NM structure. We propose a minimum of 13 cod rosettes per replicate for future studies. This research establishes a foundation for understanding marine fish NM and its response to environmental changes.

Severity of European apple canker caused by Neonectria ditissima can vary between locations and apple genotypes. We investigated how location, cold storage/planting season, and apple scion genotype affect root-associated microbial communities. Additionally, we investigated whether differences in abundance of specific taxa could be associated with canker lesion counts. Seven scion cultivars grafted onto M9 rootstocks were inoculated with N. ditissima in the nursery and then planted in December 2018 or stored at 2°C until planting in April 2019 at three sites in Kent, UK. We assessed canker lesions and collected root samples in June 2021. Quantitative polymerase chain reaction (qPCR) and internal transcribed spacer (ITS)/16S rRNA gene amplicon sequencing was used to analyse microbial communities. Site was the primary factor affecting microbiome size, diversity, and composition. Cold storage/planting season had small but significant effects, indicating that differences in the microbiome at planting can persist long-term. Scion genotype had a limited effect on diversity but did influence the abundance of specific root-associated taxa. Bacterial α-diversity was associated with canker count in a site-dependent manner. Increased abundances of particular fungal (Rhizophagus irregularis and Epicoccum nigrum) and bacterial (Amycolatopsis and Bradyrhizobium) root-associated taxa were associated with fewer cankers.

The role of microbial terroir for enhancing the geographical origin of wines is well appreciated. Still, we lack a good understanding of the assembly mechanisms driving carposphere grapevine microbiota. We investigated the role of cultivar, vintage, terroir units (TUs), and vineyard geographic location on the composition of the carpospheric microbiota of three important cultivars in the viticultural zone of Drama, Greece using amplicon sequencing. Our strategy to define TUs based on georeferencing analysis allowed us to disentangle the effects of TU and vineyards geographic location, considered as a lumped factor in most studies to date. We hypothesized that (i) these factors contribute differently on the assembly of the carposphere microbiome and that (ii) fungal and bacterial communities follow different assembly mechanisms. Vintage and TU were the stronger determinants of the carposphere fungal and bacterial communities, although the latter showed weaker response. The stronger effect of TU over vineyard geography and cultivar reinforces the role of microbial terroir in viticulture. We identified fungi (Cladosporium, Aureobasidium, Alternaria) and bacteria (Pseudomonas, Methylobacterium, Sphingomonadaceae) as main members of the core microbiome. These microorganisms were associated with specific cultivars and TUs, a feature that could be pursued towards a new microbiome-modulated paradigm of viticulture.