FEMS microbiology ecology最新文献

Kelp deforestation by sea urchin grazing is a widespread phenomenon globally, with vast consequences for coastal ecosystems. The ability of sea urchins to survive on a kelp diet of poor nutritional quality is not well understood and bacterial communities in the sea urchin intestine may play an important role in digestion. A no-choice feeding experiment was conducted with the sea urchin Strongylocentrotus droebachiensis, offering three different seaweeds as diet, including the kelp Saccharina latissima. Starved sea urchins served as experimental control. Amplicons of the 16S rRNA gene were analyzed from fecal pellets. One dominant symbiont (Psychromonas marina) accounted for 44% of all sequence reads and was especially abundant in the sea urchins fed seaweed diets. The starved and field captured sea urchins consistently displayed higher diversity than the seaweed-fed sea urchins. Cloning and sequencing of the nifH gene revealed diverse nitrogen fixers. We demonstrate that the sea urchin intestinal microbiome is dynamic, with bacterial communities that are plastic depending on diet and have the capacity for nitrogen fixation. This reflects the dietary flexibility of these sea urchins, and their intestinal microbiota could be a key component in understanding catastrophic kelp forest grazing events.

Oral antibiotic treatment is well known to be one of the main factors affecting gut microbiota composition by altering bacterial diversity. It decreases the abundance of butyrate-producing bacteria such as Lachnospiraceae and Ruminococcaceae, while increasing abundance of Enterobacteriaceae. The recovery time of commensal bacteria post-antibiotic treatment varies among individuals, and often, complete recovery is not achieved. Recently, gut microbiota disruption has been associated with increased gut oxygen levels and higher redox potential in faecal samples. Given that redox balance is crucial for microbial metabolism and gut health, influencing fermentation processes and maintaining anaerobic conditions, we investigated the impact of oral amoxicillin treatment on the redox potential in the caecum. We used 24 Wistar Han male rats and measured caecal redox potential in situ with a probe, before and after 7 days of amoxicillin treatment, as well as after 7 days of recovery. Additionally, we analysed caecal weight, pH, antioxidant capacity, caecal microbiota, metabolome, and colonic tissue expression of relevant genes involved in the redox potential state. Our findings show that oral amoxicillin treatment significantly reduced archaeal load, and decreased the bacterial alpha diversity and affected bacterial composition of the caecal microbiome. The caecal metabolome was also significantly affected, exemplified by reduced amounts of short chain fatty acids during amoxicillin treatment. While the caecal metabolome fully recovered seven days post amoxicillin treatment, the microbiome did not fully recover within this time frame. However, amoxicillin did not lead to an increase in luminal redox potential in the cecum during or post amoxicillin treatment. Limited differences were observed for colonic expression of genes involved in intestinal barrier function and generation of reactive oxygen species, except for the catalase gene, which was significantly upregulated post-amoxicillin treatment. Our results suggest that while oral amoxicillin disrupts the gut microbiome and metabolome, it does not directly interfere with gut luminal redox state.

Recently we demonstrated that the seed microbiome of certain spinach (Spinacia oleracea) seed lots can confer disease suppression against Globisporangium ultimum damping-off (previously known as Pythium ultimum). We hypothesised that differences in the microbial community composition of spinach seed lots correlate with the levels of damping-off suppressiveness of each seed lot. Here, we show that a large proportion of variance in seed-associated bacterial (16S) and fungal (ITS1) amplicon sequences was explained by seed lot identity, while 9.8% of bacterial and 7.1% of fungal community variance correlated with disease suppression. More specifically, a higher relative abundance of basidiomycetous dimorphic yeasts such as Vishniacozyma, Filobasidium and Papiliotrema and of the bacterial genus Massilia was a key feature of suppressive seed microbiomes. We suggest that the abundance of these genera is indicative of seed lot suppressive potential. Seed processing and treatment can become more targeted with indicator taxa being used to evaluate the presence of beneficial seed-associated microbial functions. This process in turn could contribute to the sustainable management of seedling diseases. Finally, this study highlights the ubiquity of yeasts in spinach seed microbiota and their potential beneficial roles for seed health.

Climate change is predicted to alter the hydrological and thermal regimes of high-mountain streams, particularly glacier-fed streams. However, relatively little is known about how these environmental changes impact the microbial communities in glacier-fed streams. Here, we operated streamside flume mesocosms in the Swiss Alps, where benthic biofilms were grown under treatments simulating climate change. Treatments comprised four flow (natural, intermittent, stochastic, and constant) and two temperature (ambient streamwater and warming of +2°C) regimes. We monitored microbial biomass, diversity, community composition, and metabolic diversity in biofilms over 3 months. We found that community composition was largely influenced by successional dynamics independent of the treatments. While stochastic and constant flow regimes did not significantly affect community composition, droughts altered their composition in the intermittent regime, favouring drought-adapted bacteria and decreasing algal biomass. Concomitantly, warming decreased algal biomass and the abundance of some typical glacier-fed stream bacteria and eukaryotes, and stimulated heterotrophic metabolism overall. Our study provides experimental evidence towards potential and hitherto poorly considered impacts of climate change on benthic biofilms in glacier-fed streams.

Free-living amoebae (FLA) are described as environmental reservoirs for some bacteria able to resist their phagocytosis. In the environment, the fate of Mycobacterium bovis (Mbo) and Mycobacterium avium subsp. paratuberculosis (Map) responsible for bovine tuberculosis and paratuberculosis, respectively, remains poorly understood and is considered potentially problematic in the eradication and control of these diseases. We hypothesize that FLA may play a role in the persistence of Mbo and Map in the environment. In this study, 90 samples were collected from herds affected by one or both diseases to investigate the diversity of amoeba and their associated bacteria. Metabarcoding analyses revealed that Acanthamoeba, Copromyxa, Naegleria, and Vermamoeba were the most represented genera of FLA, with Pseudomonadota being the bacteria most commonly found associated with FLA. Although no Mbo and Map DNA were identified by sequencing, traces were detected by ddPCR (digital droplet PCR), specifically targeting these bacteria. In conclusion, we described a wide diversity of FLA and associated bacteria in this environment. It also suggests that Map and Mbo could be associated, even weakly, with FLA in the environment. However, this needs to be confirmed by detecting a highest amount of DNA and, if possible, cultivable Map and/or Mbo associated with these environmental FLA.

The built environment provides an excellent setting for interdisciplinary research on the dynamics of microbial communities. The system is simplified compared to many natural settings, and to some extent the entire environment can be manipulated, from architectural design to materials use, air flow, human traffic, and capacity to disrupt microbial communities through cleaning. Here, we provide an overview of the ecology of the microbiome in the built environment. We address niche space and refugia, population, and community (metagenomic) dynamics, spatial ecology within a building, including the major microbial transmission mechanisms, as well as evolution. We also address landscape ecology, connecting microbiomes between physically separated buildings. At each stage, we pay particular attention to the actual and potential interface between disciplines, such as ecology, epidemiology, materials science, and human social behavior. We end by identifying some opportunities for future interdisciplinary research on the microbiome of the built environment.

The physical and chemical properties of wild berry fruits change dramatically during development, and the ripe berries host species-specific endophytic communities. However, the development of fungal endophytic communities during berry ripening is unknown. We studied bilberries (Vaccinium myrtillus L.), valuable natural resources in northern Europe and richest sources of phenolic compounds, to characterize dynamics of the fungal communities over fruit developmental stages (raw, veraison, and ripe). Our focus was to examine the changes in the fruit phenolic compounds associated with the fungal community structure using liquid chromatography-mass spectrometry for phenolic compounds and high-throughput sequencing technology targeting the internal transcribed spacer 2 ribosomal DNA region for endophytic fungi. We found that the fungal diversity increased with the ripening stages. The fungal profile changed dramatically through fruit development, and the veraison stage was a transition stage, where the core mycobiome of fruits changed. The fungal community structure and abundance of the most dominant genera in raw and ripe stages, Monilinia and Cladosporium, respectively, were driven by the bilberry phenolic profile. We conclude that sampling time, tissue age, and phenolic compounds play important roles in the development of fruit fungal community. Moreover, phenolic compounds could be the host's strategy to recruit beneficial microbes.

Lake Sentani is a tropical lake in Indonesia, consisting of four interconnected sub-basins of different water depths. While previous work has highlighted the impact of catchment composition on biogeochemical processes in Lake Sentani, little is currently known about the microbiological characteristics across this unique ecosystem. With recent population growth in this historically rural area, the anthropogenic impact on Lake Sentani and hence its microbial life is also increasing. Therefore, we aimed to explore the influence of environmental and anthropogenic factors on the microbial diversity of Lake Sentani. Here, we present a detailed microbiological evaluation of Lake Sentani, analyzing 49 different sites across the lake, its tributary rivers and their river mouths to assess diversity and community structure using 16S rRNA gene sequencing. Our results reveal distinct communities in lake and river sediments, supporting the observed geochemical differences. Taxonomic assessment showed the potential impact of anthropogenic pressure along the northern, urbanized shore, as river and river mouth samples revealed high abundances of Bacteroidota, Firmicutes, and Cyanobacteria, which could be attributed to pollution and eutrophication. In contrast, lake sediment communities were dominated by Thermodesulfovibrionia, Methanomethylicia, Bathyarchaeia, and Thermoplasmata, suggesting sulfate reducing, thermophilic, acidophilic bacteria and methanogenic archaea to play an important role in tropical lake systems. This study provides novel insights into ecological functions of tropical lakes and contributes to the optimization of management strategies of Lake Sentani, ensuring its holistic preservation in the future.

The thermophilic bacterium Rhodothermus marinus has mainly been studied for its thermostable enzymes. More recently, the potential of using the species as a cell factory and in biorefinery platforms has been explored, due to the elevated growth temperature, native production of compounds such as carotenoids and exopolysaccharides, the ability to grow on a wide range of carbon sources including polysaccharides, and available genetic tools. A comprehensive understanding of the metabolism of cell factories is important. Here, we report a genome-scale metabolic model of R. marinus DSM 4252T. Moreover, the genome of the genetically amenable R. marinus ISCaR-493 was sequenced and the analysis of the core genome indicated that the model could be used for both strains. Bioreactor growth data were obtained, used for constraining the model and the predicted and experimental growth rates were compared. The model correctly predicted the growth rates of both strains. During the reconstruction process, different aspects of the R. marinus metabolism were reviewed and subsequently, both cell densities and carotenoid production were investigated for strain ISCaR-493 under different growth conditions. Additionally, the dxs gene, which was not found in the R. marinus genomes, from Thermus thermophilus was cloned on a shuttle vector into strain ISCaR-493 resulting in a higher yield of carotenoids.

The gut microbiota, which includes prokaryotes, archaea, and eukaryotes such as yeasts, some protozoa, and fungi, significantly impacts fish by affecting digestion, metabolism, and the immune system. In this research, we combine various tasks carried out by various bacteria in the gut of fish. This study also examines the gut microbiome composition of marine and freshwater fish, identifying important bacterial species linked to different biological functions. The diversity within fish species highlights the importance of considering nutrition, habitat, and environmental factors in microbiological research on fish. The ever-changing gut microbiome of the fish indicates that microbial communities are specifically adapted to meet the needs of both the host and its environment. This indicates that the fish can adjust to a specific environment with the help of gut microbiota. This important research is crucial for comprehending the complex relationships between fish and their gut bacteria in different aquatic environments. These discoveries have implications for aquaculture practices, fisheries administration, and the broader ecological processes of both freshwater and marine environments. With further progress in this area of study, the knowledge acquired would offer a valuable standpoint to enhance our comprehension of aquatic microbiology and enhance the sustainability and nutrition of fish resources.