Enhancing seafood traceability: tracking the origin of seabass and seabream from the tuscan coast area by the analysis of the gill bacterial communities.

BACKGROUND: The seafood consumption and trade have increased over the years, and along its expected expansion pose major challenges to the seafood industry and government institutions. In particular, the global trade in fish products and the consequent consumption are linked to reliable authentication, necessary to guarantee lawful trade and healthy consumption. Alterations or errors in this process can lead to commercial fraud and/or health threats. Consequently, the development of new investigative tools became crucial in ensuring unwanted scenarios. Here we used NGS techniques through targeted metagenomics approach on the V3-V4 region of the 16S rRNA genes to characterize the gill bacterial communities in wild-caught seabream (Sparus aurata) and seabass (Dicentrarchus labrax) within different fisheries areas of the "Costa degli Etruschi'' area in the Tuscan coast. Our challenge involved the possibility of discriminating between the microbiota of both fish species collected from three different fishing sites very close to each other (all within 100 km) in important areas from a commercial and tourist point of view. RESULTS: Our results showed a significant difference in the assembly of gill bacterial communities in terms of diversity (alpha and beta diversity) of both seabass and seabream in accordance with the three fishing areas. These differences were represented by a unique site -related bacterial signature, more evident in seabream compared to the seabass. Accordingly, the core membership of seabream specimens within the three different sites was minimal compared to the seabass which showed a greater number of sequence variants shared among the different fishing sites. Therefore, the LRT analysis highlighted the possibility of obtaining specific fish bacterial signatures associated with each site; it is noteworthy that specific taxa showed a unique association with the fishing site regardless of the fish species. This study demonstrates the effectiveness of target-metagenomic sequencing of gills in discriminating bacterial signatures of specimens collected from fishing areas located at a limited distance to each other. CONCLUSIONS: This study provides new information relating the structure of the gill microbiota of seabass and seabream in a fishing area with a crucial commercial and tourist interest, namely "Costa degli Etruschi". This study demonstrated that microbiome-based approaches can represent an important tool for validating the seafood origins with a central applicative perspective in the seafood traceability system.

Last-mile delivery increases vaccine uptake in Sierra Leone.

Less than 30% of people in Africa received a dose of the COVID-19 vaccine even 18 months after vaccine development1. Here, motivated by the observation that residents of remote, rural areas of Sierra Leone faced severe access difficulties2, we conducted an intervention with last-mile delivery of doses and health professionals to the most inaccessible areas, along with community mobilization. A cluster randomized controlled trial in 150 communities showed that this intervention with mobile vaccination teams increased the immunization rate by about 26 percentage points within 48-72 h. Moreover, auxiliary populations visited our community vaccination points, which more than doubled the number of inoculations administered. The additional people vaccinated per intervention site translated to an implementation cost of US $33 per person vaccinated. Transportation to reach remote villages accounted for a large share of total intervention costs. Therefore, bundling multiple maternal and child health interventions in the same visit would further reduce costs per person treated. Current research on vaccine delivery maintains a large focus on individual behavioural issues such as hesitancy. Our study demonstrates that prioritizing mobile services to overcome access difficulties faced by remote populations in developing countries can generate increased returns in terms of uptake of health services3.

Ascomycetes yeasts: The hidden part of human microbiome.

The fungal component of the microbiota, the mycobiota, has been neglected for a long time due to its poor richness compared to bacteria. Limitations in fungal detection and taxonomic identification arise from using metagenomic approaches, often borrowed from bacteriome analyses. However, the relatively recent discoveries of the ability of fungi to modulate the host immune response and their involvement in human diseases have made mycobiota a fundamental component of the microbial communities inhabiting the human host, deserving some consideration in host-microbe interaction studies and in metagenomics. Here, we reviewed recent data on the identification of yeasts of the Ascomycota phylum across human body districts, focusing on the most representative genera, that is, Saccharomyces and Candida. Then, we explored the key factors involved in shaping the human mycobiota across the lifespan, ranging from host genetics to environment, diet, and lifestyle habits. Finally, we discussed the strengths and weaknesses of culture-dependent and independent methods for mycobiota characterization. Overall, there is still room for some improvements, especially regarding fungal-specific methodological approaches and bioinformatics challenges, which are still critical steps in mycobiota analysis, and to advance our knowledge on the role of the gut mycobiota in human health and disease. This article is categorized under: Immune System Diseases > Genetics/Genomics/Epigenetics Immune System Diseases > Environmental Factors Infectious Diseases > Environmental Factors.

The yeast-human coevolution: Fungal transition from passengers, colonizers, and invaders.

Fungi are the cause of more than a billion infections in humans every year, although their interactions with the host are still neglected compared to bacteria. Major systemic fungal infections are very unusual in the healthy population, due to the long history of coevolution with the human host. Humans are routinely exposed to environmental fungi and can host a commensal mycobiota, which is increasingly considered as a key player in health and disease. Here, we review the current knowledge on host-fungi coevolution and the factors that regulate their interaction. On one hand, fungi have learned to survive and inhabit the host organisms as a natural ecosystem, on the other hand, the host immune system finely tunes the response toward fungi. In turn, recognition of fungi as commensals or pathogens regulates the host immune balance in health and disease. In the human gut ecosystem, yeasts provide a fingerprint of the transient microbiota. Their status as passengers or colonizers is related to the integrity of the gut barrier and the risk of multiple disorders. Thus, the study of this less known component of the microbiota could unravel the rules of the transition from passengers to colonizers and invaders, as well as their dependence on the innate component of the host's immune response. This article is categorized under: Infectious Diseases > Environmental Factors Immune System Diseases > Environmental Factors Infectious Diseases > Molecular and Cellular Physiology.

Species-specific gill's microbiome of eight crab species with different breathing adaptations.

Transitions to physically different environments, such as the water-to-land transition, proved to be the main drivers of relevant evolutionary events. Brachyuran crabs evolved remarkable morphological, behavioral, and physiological adaptations to terrestrial life. Terrestrial species evolved new respiratory structures devoted to replace or support the gills, a multifunctional organ devoted to gas exchanges, ion-regulation and nitrogen excretion. It was hypothesized that microorganisms associated with respiratory apparatus could have facilitated the processes of osmoregulation, respiration, and elimination of metabolites along this evolutionary transition. To test if crab species with different breathing adaptations may host similar microbial communities on their gills, we performed a comparative targeted-metagenomic analysis, selecting two marine and six terrestrial crabs belonging to different families and characterised by different breathing adaptations. We analysed anterior and posterior gills separately according to their different and specific roles. Regardless of their terrestrial or marine adaptations, microbial assemblages were strongly species-specific indicating a non-random association between the host and its microbiome. Significant differences were found in only two terrestrial species when considering posterior vs. anterior gills, without any association with species-specific respiratory adaptations. Our results suggest that all the selected species are strongly adapted to the ecological niche and specific micro-habitat they colonise.

Using wasps as a tool to restore a functioning vine grape mycobiota and preserve the mycobial "terroir".

In the last one-hundred years, the exponential expansion of wine making has artificialized the agricultural landscape as well as its microbial diversity, spreading human selected Saccharomyces cerevisiae strains. Evidence showed that social wasps can harbor a significant fraction of the yeast phenotypic diversity of a given area of wine production, allowing different strains to overwinter and mate in their gut. The integrity of the wasp-yeast ecological interaction is of paramount importance to maintain the resilience of microbial populations associated to wine aromatic profiles. In a field experiment, we verified whether Polistes dominula wasps, reared in laboratory and fed with a traceable S. cerevisiae strain, could be a useful tool to drive the controlled yeast dispersion directly on grapes. The demonstration of the biotechnological potential of social insects in organic wine farming lays the foundations for multiple applications including maintenance of microbial biodiversity and rewilding vineyards through the introduction of wasp associated microbiomes.

Vaginal Microbiome in Pregnant Women with and without Short Cervix.

Cervical shortening is a recognised risk factor for pre-term birth. The vaginal microbiome plays an essential role in pregnancy and in maternal and foetal outcomes. We studied the vaginal microbiome in 68 women with singleton gestation and a cervical length ≤25 mm and in 29 pregnant women with a cervix >25 mm in the second or early third trimester. Illumina protocol 16S Metagenomic Sequencing Library Preparation was used to detail amplified 16SrRNA gene. Statistical analyses were performed in R environment. Firmicutes was the phylum most represented in all pregnant women. The mean relative abundance of Proteobacteria and Actinobacteriota was higher in women with a short cervix. Bacterial abundance was higher in women with a normal length cervix compared to the group of women with a short cervix. Nonetheless, a significant enrichment in bacterial taxa poorly represented in vaginal microbiome was observed in the group of women with a short cervix. Staphylococcus and Pseudomonas, taxa usually found in aerobic vaginitis, were more common in women with a short cervix compared with the control group, while Lactobacillus iners and Bifidobacterium were associated with a normal cervical length. Lactobacillus jensenii and Gardenerella vaginalis were associated with a short cervix.

Mutualistic Relationships between Microorganisms and Eusocial Wasps (Hymenoptera, Vespidae).

Eusocial wasps are represented in the Vespidae by the subfamilies Stenogastrinae, Vespinae and Polistinae. These wasps present colonies that are sometimes composed of thousands of individuals which live in nests built with paper materials. The high density of the adult and larval population, as well as the stable micro environment of the nests, make very favourable conditions for the flourishing of various types of microorganisms. These microorganisms, which may be pathogens, are beneficial and certainly contribute to model the sociality of these insects. The mutualistic relationships that we observe in some species, especially in Actinomycete bacteria and yeasts, could have important fallouts for the development of new medicines and for the use of these insects in agricultural environments.

Conserved organ-specific microbial assemblages in different populations of a terrestrial crab.

Microorganisms are ubiquitous in the environment and provide genetic and physiological functions to multicellular organisms. Knowledge on the associated microbiota is becoming highly relevant to understand the host's ecology and biology. Among invertebrates, many examples of endosymbiosis have been described, such as those in corals, ants, and termites. At present, however, little is known on the presence, diversity, and putative roles of the microbiota associated to brachyuran crabs in relation to their environment. In this work we investigated the associated microbiota of three populations of the terrestrial brachyuran crab Chiromantes haematocheir to find evidence of a conserved organ-specific microbiome unrelated to the population of origin and dissimilar from environmental microbial assemblages. Bacterial 16S rRNA gene and fungal ITS sequences were obtained from selected crab organs and environmental matrices to profile microbial communities. Despite the presence of truly marine larval stages and the absence of a gregarious behaviour, favouring microbiota exchanges, we found common, organ-specific microbiota, associated with the gut and the gills of crabs from the different populations (with more than 15% of the genera detected specifically enriched only in one organ). These findings suggest the presence of possible functional roles of the organ-specific microbiota.

COVID-19 and mental health in 8 low- and middle-income countries: A prospective cohort study.

BACKGROUND: The Coronavirus Disease 2019 (COVID-19) pandemic and associated mitigation policies created a global economic and health crisis of unprecedented depth and scale, raising the estimated prevalence of depression by more than a quarter in high-income countries. Low- and middle-income countries (LMICs) suffered the negative effects on living standards the most severely. However, the consequences of the pandemic for mental health in LMICs have received less attention. Therefore, this study assesses the association between the COVID-19 crisis and mental health in 8 LMICs. METHODS AND FINDINGS: We conducted a prospective cohort study to examine the correlation between the COVID-19 pandemic and mental health in 10 populations from 8 LMICs in Asia, Africa, and South America. The analysis included 21,162 individuals (mean age 38.01 years, 64% female) who were interviewed at least once pre- as well as post-pandemic. The total number of survey waves ranged from 2 to 17 (mean 7.1). Our individual-level primary outcome measure was based on validated screening tools for depression and a weighted index of depression questions, dependent on the sample. Sample-specific estimates and 95% confidence intervals (CIs) for the association between COVID-19 periods and mental health were estimated using linear regressions with individual fixed effects, controlling for independent time trends and seasonal variation in mental health where possible. In addition, a regression discontinuity design was used for the samples with multiple surveys conducted just before and after the onset of the pandemic. We aggregated sample-specific coefficients using a random-effects model, distinguishing between estimates for the short (0 to 4 months) and longer term (4+ months). The random-effects aggregation showed that depression symptoms are associated with a increase by 0.29 standard deviations (SDs) (95% CI [-.47, -.11], p-value = 0.002) in the 4 months following the onset of the pandemic. This change was equivalent to moving from the 50th to the 63rd percentile in our median sample. Although aggregate depression is correlated with a decline to 0.21 SD (95% CI [-0.07, -.34], p-value = 0.003) in the period thereafter, the average recovery of 0.07 SD (95% CI [-0.09, .22], p-value = 0.41) was not statistically significant. The observed trends were consistent across countries and robust to alternative specifications. Two limitations of our study are that not all samples are representative of the national population, and the mental health measures differ across samples. CONCLUSIONS: Controlling for seasonality, we documented a large, significant, negative association of the pandemic on mental health, especially during the early months of lockdown. The magnitude is comparable (but opposite) to the effects of cash transfers and multifaceted antipoverty programs on mental health in LMICs. Absent policy interventions, the pandemic could be associated with a lasting legacy of depression, particularly in settings with limited mental health support services, such as in many LMICs. We also demonstrated that mental health fluctuates with agricultural crop cycles, deteriorating during "lean", pre-harvest periods and recovering thereafter. Ignoring such seasonal variations in mental health may lead to unreliable inferences about the association between the pandemic and mental health.

COVID-19 vaccine acceptance and hesitancy in low- and middle-income countries.

Widespread acceptance of COVID-19 vaccines is crucial for achieving sufficient immunization coverage to end the global pandemic, yet few studies have investigated COVID-19 vaccination attitudes in lower-income countries, where large-scale vaccination is just beginning. We analyze COVID-19 vaccine acceptance across 15 survey samples covering 10 low- and middle-income countries (LMICs) in Asia, Africa and South America, Russia (an upper-middle-income country) and the United States, including a total of 44,260 individuals. We find considerably higher willingness to take a COVID-19 vaccine in our LMIC samples (mean 80.3%; median 78%; range 30.1 percentage points) compared with the United States (mean 64.6%) and Russia (mean 30.4%). Vaccine acceptance in LMICs is primarily explained by an interest in personal protection against COVID-19, while concern about side effects is the most common reason for hesitancy. Health workers are the most trusted sources of guidance about COVID-19 vaccines. Evidence from this sample of LMICs suggests that prioritizing vaccine distribution to the Global South should yield high returns in advancing global immunization coverage. Vaccination campaigns should focus on translating the high levels of stated acceptance into actual uptake. Messages highlighting vaccine efficacy and safety, delivered by healthcare workers, could be effective for addressing any remaining hesitancy in the analyzed LMICs.

Falling living standards during the COVID-19 crisis: Quantitative evidence from nine developing countries.

Despite numerous journalistic accounts, systematic quantitative evidence on economic conditions during the ongoing COVID-19 pandemic remains scarce for most low- and middle-income countries, partly due to limitations of official economic statistics in environments with large informal sectors and subsistence agriculture. We assemble evidence from over 30,000 respondents in 16 original household surveys from nine countries in Africa (Burkina Faso, Ghana, Kenya, Rwanda, Sierra Leone), Asia (Bangladesh, Nepal, Philippines), and Latin America (Colombia). We document declines in employment and income in all settings beginning March 2020. The share of households experiencing an income drop ranges from 8 to 87% (median, 68%). Household coping strategies and government assistance were insufficient to sustain precrisis living standards, resulting in widespread food insecurity and dire economic conditions even 3 months into the crisis. We discuss promising policy responses and speculate about the risk of persistent adverse effects, especially among children and other vulnerable groups.

Active microbial ecosystem in Iron-Age tombs of the Etruscan civilization.

Earth's microbial biosphere extends down through the crust and much of the subsurface, including those microbial ecosystems located within cave systems. Here, we elucidate the microbial ecosystems within anthropogenic 'caves'; the Iron-Age, subterranean tombs of central Italy. The interior walls of the rock (calcium-rich macco) were painted ~2500 years ago and are covered with CaCO3 needles (known as moonmilk). The aims of the current study were to: identify biological/geochemical/biophysical determinants of and characterize bacterial communities involved in CaCO3 precipitation; challenge the maxim that biogenic activity necessarily degrades surfaces; locate the bacterial cells that are the source of the CaCO3 precipitate; and gain insight into the kinetics of moonmilk formation. We reveal that this environment hosts communities that consist primarily of bacteria that are mesophilic for temperature and xerotolerance (including Actinobacteria, Bacteroidetes and Proteobacteria); is populated by photosynthetic Cyanobacteria exhibiting heterotrophic nutrition (Calothrix and Chroococcidiopsis); and has CaCO3 precipitating on the rock surfaces (confirmation that this process is biogenic) that acts to preserve rather than damage the painted surface. We also identified that some community members are psychrotolerant (Polaromonas), acidotolerant or acidophilic (members of the Acidobacteria), or resistant to ionizing radiation (Brevundimonas and Truepera); elucidate the ways in which microbiology impacts mineralogy and vice versa; and reveal that biogenic formation of moonmilk can occur rapidly, that is, over a period of 10 to 56 years. We discuss the paradox that these ecosystems, that are for the most part in the dark and lack primary production, are apparently highly active, biodiverse and biomass-rich.

Altered feeding behavior and immune competence in paper wasps: A case of parasite manipulation?

Paper wasps (Polistes dominula), parasitized by the strepsipteran Xenos vesparum, are castrated and desert the colony to gather on plants where the parasite mates and releases primary larvae, thus completing its lifecycle. One of these plants is the trumpet creeper Campsis radicans: in a previous study the majority of all wasps collected from this plant were parasitized and focused their foraging activity on C. radicans buds. The unexpected prevalence and unusual feeding strategy prompted us to investigate the influence of this plant on wasp behavior and physiology through a multidisciplinary approach. First, in a series of laboratory bioassays, we observed that parasitized wasps spent more time than non-parasitized ones on fresh C. radicans buds, rich of extra-floral nectaries (EFNs), while the same wasps ignored treated buds that lacked nectar drops. Then, we described the structure and ultra-structure of EFNs secreting cells, compatible with the synthesis of phenolic compounds. Subsequently, we analysed extracts from different bud tissues by HPLC-DAD-MS and found that verbascoside was the most abundant bioactive molecule in those tissues rich in EFNs. Finally, we tested the immune-stimulant properties of verbascoside, as the biochemical nature of this compound indicates it might function as an antibacterial and antioxidant. We measured bacterial clearance in wasps, as a proxy for overall immune competence, and observed that it was enhanced after administration of verbascoside-even more so if the wasp was parasitized. We hypothesize that the parasite manipulates wasp behavior to preferentially feed on C. radicans EFNs, since the bioactive properties of verbascoside likely increase host survival and thus the parasite own fitness.

Applications of Wild Isolates of Saccharomyces Yeast for Industrial Fermentation: The Gut of Social Insects as Niche for Yeast Hybrids' Production.

In the industry of fermented food and beverages, yeast cultures are often selected and standardized in order to ensure a better control of fermentation and a more stable product over time. Several studies have shown that the organoleptic characteristics of fermented products reflect geographic variations of the microbial community composition. Despite investigations of the worldwide distribution and genetic diversity of Saccharomyces cerevisiae, it is still unclear how and to what extent human intervention has shaped the brewer's yeast population structure. The genotypic and phenotypic characterization of environmental yeast populations and their potential application in the fermentative processes can significantly enrich the industrial fermentation products. Social insects have proven to be closely associated to the yeasts ecology. The relationships between yeasts and insects represent a fundamental aspect for understanding the ecological and evolutionary forces shaping their adaptation to different niches. Studies on phylogenetic relationships of S. cerevisiae populations showed genetic differences among strains isolated from gut and non-gut environments (i.e., natural sources and fermentation). Recent evidences showed that insect's gut is a reservoir and an evolutionary niche for Saccharomyces, contributing to its survival and evolution, favoring its dispersion, mating and improving the inter-specific hybrids production during hibernation. Here, we discuss the potential use of social insects for production of a wide range of hybrid yeasts from environmental Saccharomyces isolates suitable for industrial and biotechnological applications.

To the Land and Beyond: Crab Microbiomes as a Paradigm for the Evolution of Terrestrialization.

The transition to terrestrial environments by formerly aquatic species has occurred repeatedly in many animal phyla and lead to the vast diversity of extant terrestrial species. The differences between aquatic and terrestrial habitats are enormous and involved remarkable morphological and physiological changes. Convergent evolution of various traits is evident among phylogenetically distant taxa, but almost no information is available about the role of symbiotic microbiota in such transition. Here, we suggest that intertidal and terrestrial brachyuran crabs are a perfect model to study the evolutionary pathways and the ecological role of animal-microbiome symbioses, since their transition to land is happening right now, through a number of independent lineages. The microorganisms colonizing the gut of intertidal and terrestrial crabs are expected to play a major role to conquer the land, by reducing water losses and permitting the utilization of novel food sources. Indeed, it has been shown that the microbiomes hosted in the digestive system of terrestrial isopods has been critical to digest plant items, but nothing is known about the microbiomes present in the gut of truly terrestrial crabs. Other important physiological regulations that could be facilitated by microbiomes are nitrogen excretion and osmoregulation in the new environment. We also advocate for advances in comparative and functional genomics to uncover physiological aspects of these ongoing evolutionary processes. We think that the multidisciplinary study of microorganisms associated with terrestrial crabs will shed a completely new light on the biological and physiological processes involved in the sea-land transition.

Saccharomyces cerevisiae - Insects Association: Impacts, Biogeography, and Extent.

Over the last few years, an increasing number of studies have reported the existence of an association between the budding yeast Saccharomyces cerevisiae and insects. The discovery of this relationship has called into question the hypothesis that S. cerevisiae is unable to survive in nature and that the presence of S. cerevisiae strains in natural specimens is the result of contamination from human-related environments. S. cerevisiae cells benefit from this association as they find in the insect intestine a shelter, but also a place where they can reproduce themselves through mating, the latter being an event otherwise rarely observed in natural environments. On the other hand, insects also take advantage in hosting S. cerevisiae as they rely on yeasts as nutriment to properly develop, to localize suitable food, and to enhance their immune system. Despite the relevance of this relationship on both yeast and insect ecology, we are still far from completely appreciating its extent and effects. It has been shown that other yeasts are able to colonize only one or a few insect species. Is it the same for S. cerevisiae cells or is this yeast able to associate with any insect? Similarly, is this association geographically or topographically limited in areas characterized by specific physical features? With this review, we recapitulate the nature of the S. cerevisiae-insect association, disclose its extent in terms of geographical distribution and species involved, and present YeastFinder, a cured online database providing a collection of information on this topic.

Gut microbial composition in different castes and developmental stages of the invasive hornet Vespa velutina nigrithorax.

Social insects are successful animal invaders. Their survival and success, and in some cases also their impact on invaded ecosystem functioning, is often mediated by symbiosis with microorganisms. Here, we report a comprehensive comparative characterization of the gut microbial communities of different castes and developmental stages of the invasive hornet Vespa velutina nigrithorax. The species recently colonized Europe, becoming a high ecological and economic concern, as it threatens pollinator survival and competes with native hornet species. We used targeted meta-genomics to describe the yeasts and bacteria gut communities of individuals of different reproductive phenotypes (workers and future queens), life stages (larvae, newly emerged individuals and adults) and colony non-living samples (nest paper and larval faeces). Bacilli, Gammaproteobacteria, Actinobacteria, Alphaproteobacteria were the most abundant classes of bacteria, and Saccharomycetes, Dothideomycetes, Tremellomycetes and Eurotiomycetes were the most represented yeast classes. We found that the microbial compositions significantly differ across developmental stages and castes, with yeast and bacterial communities switching in frequency and abundance during ontogeny and according to reproductive phenotype. Moreover, the gut microbial communities poorly mirror those found in the nest, suggesting that hornets possess a specific microbial signature. Our results provide the first metagenomic resource of the microbiome of V. velutina in Europe and suggest the importance of considering life stages, reproductive phenotypes and nest influence in order to obtain a comprehensive picture of social insect microbial communities.

Saccharomyces cerevisiae Induces Immune Enhancing and Shapes Gut Microbiota in Social Wasps.

Trained immunity is the enhanced response of the innate immune system to a secondary infection after an initial encounter with a microorganism. This non-specific response to reinfection is a primitive form of adaptation that has been shown to be conserved from plants to mammals. Insects lack an acquired immune component and rely solely on an innate one, and they have expanded it upon traits of plasticity and adaptation against pathogens in the form of immune priming. The recent discoveries of the role of Saccharomyces cerevisiae in the insect's ecology and the ability of this yeast to induce trained immunity in different organisms suggest that insects could have developed mechanisms of adaptation and immune enhancing. Here, we report that two yeast strains of S. cerevisiae, previously shown to induce trained immunity in mammals, enhance resistance to Escherichia coli infection in the paper wasp Polistes dominula. The reduction of injected E. coli load by S. cerevisiae strains was statistically significant in future foundresses but not in workers, and this occurs before and after hibernation. We thus investigated if the effect on E. coli was mirrored by variation in the gut microbiota composition. Foundresses, showing immune enhancing, had statistically significant changes in composition and diversity of gut bacterial communities but not in the fungal communities. Our results demonstrate that S. cerevisiae can prime insect responses against bacterial infections, providing an advantage to future foundress wasps to carry these microorganisms. Understanding the mechanisms involved in the generation of specific and long-lasting immune response against pathogenic infections in insects and the influence of the induction of trained immunity on the commensal gut microbiota could have a major impact on modern immunology.