FEMS microbiology ecology最新文献

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.

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 to 38 fish reared under ambient conditions. Additionally, we conducted an experiment to investigate the influence of acidification and a simplified heatwave on cod NM (3 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.

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.

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 characterised 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 kilometres, 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.

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 affects 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, pin points the cascading effects of tree infestations by bark beetles and subsequent tree dieback 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 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.

Diurnal rhythms of the gut microbiota are emerging as an important yet often overlooked facet of microbial ecology. Feeding is thought to stimulate gut microbial rhythmicity, but this has not been explicitly tested. Moreover, the role of the gut environment is entirely unexplored, with rhythmic changes to gut pH rather than feeding per se possibly affecting gut microbial fluctuations. In this study, we experimentally manipulated the feeding schedule of captive lesser long-nosed bats, Leptonycteris yerbabuenae, to dissociate photic and feeding cues, and measured the faecal microbiota and gut pH every 2 h. We detected strong diurnal rhythms in both microbial alpha diversity and beta diversity as well as in pH within the control group. However, a delay in feeding disrupted oscillations of gut microbial diversity and composition, but did not affect rhythms in gut pH. The oscillations of some genera, such as Streptococcus, which aid in metabolizing nutrients, shifted in accordance with the delayed-feeding cue and were correlated with pH. For other bacterial genera, oscillations were disturbed and no connection to pH was found. Our findings suggest that the rhythmic proliferation of bacteria matches peak feeding times, providing evidence that diurnal rhythms of the gut microbiota likely evolved to optimize their metabolic support to the host's circadian phenotype.

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 7 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.

Despite the beneficial effects of plant growth-promoting rhizobacteria on agriculture, understanding the consequences of introducing foreign microbes into soil taxonomic and functional diversity is necessary. This study evaluated the effects co-inoculation of soybean with Bacillus thuringiensis (Bt) RZ2MS9 and commercial rhizobia on the natural microbial community structure and functional potential. Our results indicated that soybean development was positively influenced by co-inoculation, plants exhibited greater height and a higher number of pods, and no reductions in productivity estimates. Soil prokaryotic diversity and community structure remained unchanged by Bt RZMS9 inoculation or co-inoculation with rhizobia 147 days after sowing. However, functional diversity was influenced by sole Bt inoculation, potentially due to community quorum sensing disruption by N-acyl homoserine lactone hydrolases. The genes enriched by co-inoculation were mostly related to soil phosphorus cycling, with gcd showing the most pronounced increase. The nifA genes increased when rhizobia alone were inoculated, suggesting that this pathway could be affected by Bt RZ2MS9 inoculation. This study demonstrates the synergistic activity of rhizobia and Bt RZ2MS9 on soybean development, without significantly interfering with natural microbial community, presenting a promising approach for sustainable crop management.