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

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.

Yeast-insect interactions in southern Africa: Tapping the diversity of yeasts for modern bioprocessing

Yeast-insect interactions are one of the most interesting long-standing relationships whose research has contributed to our understanding of yeast biodiversity and their industrial applications. Although insect-derived yeast strains are exploited for industrial fermentations, only a limited number of such applications has been documented. The search for novel yeasts from insects is attractive to augment the currently domesticated and commercialized production strains. More specifically, there is potential in tapping the insects native to southern Africa. Southern Africa is home to a disproportionately high fraction of global biodiversity with a cluster of biomes and a broad climate range. This review presents arguments on the roles of the mutualistic relationship between yeasts and insects, the presence of diverse pristine environments and a long history of spontaneous food and beverage fermentations as the potential source of novelty. The review further discusses the recent advances in novelty of industrial strains of insect origin, as well as various ancient and modern-day industries that could be improved by use yeasts from insect origin. The major focus of the review is on the relationship between insects and yeasts in southern African ecosystems as a potential source of novel industrial yeast strains for modern bioprocesses.

The complex interactions between nutrition, immunity and infection in insects

Insects are the most diverse animal group on the planet. Their success is reflected by the diversity of habitats in which they live. However, these habitats have undergone great changes in recent decades; understanding how these changes affect insect health and fitness is an important challenge for insect conservation. In this Review, we focus on the research that links the nutritional environment with infection and immune status in insects. We first discuss the research from the field of nutritional immunology, and we then investigate how factors such as intracellular and extracellular symbionts, sociality and transgenerational effects may interact with the connection between nutrition and immunity. We show that the interactions between nutrition and resistance can be highly specific to insect species and/or infection type - this is almost certainly due to the diversity of insect social interactions and life cycles, and the varied environments in which insects live. Hence, these connections cannot be easily generalised across insects. We finally suggest that other environmental aspects - such as the use of agrochemicals and climatic factors - might also influence the interaction between nutrition and resistance, and highlight how research on these is essential.

Bees just wanna have fungi: a review of bee associations with nonpathogenic fungi

Bee-fungus associations are common, and while most studies focus on entomopathogens, emerging evidence suggests that bees associate with a variety of symbiotic fungi that can influence bee behavior and health. Here, we review nonpathogenic fungal taxa associated with different bee species and bee-related habitats. We synthesize results of studies examining fungal effects on bee behavior, development, survival, and fitness. We find that fungal communities differ across habitats, with some groups restricted mostly to flowers (Metschnikowia), while others are present almost exclusively in stored provisions (Zygosaccharomyces). Starmerella yeasts are found in multiple habitats in association with many bee species. Bee species differ widely in the abundance and identity of fungi hosted. Functional studies suggest that yeasts affect bee foraging, development, and pathogen interactions, though few bee and fungal taxa have been examined in this context. Rarely, fungi are obligately beneficial symbionts of bees, whereas most are facultative bee associates with unknown or ecologically contextual effects. Fungicides can reduce fungal abundance and alter fungal communities associated with bees, potentially disrupting bee-fungi associations. We recommend that future study focus on fungi associated with non-honeybee species and examine multiple bee life stages to document fungal composition, abundance, and mechanistic effects on bees.

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.

Non-saccharomyces yeast probiotics: revealing relevance and potential

Non-Saccharomyces yeasts are unicellular eukaryotes that play important roles in diverse ecological niches. In recent decades, their physiological and morphological properties have been reevaluated and reassessed, demonstrating the enormous potential they possess in various fields of application. Non-Saccharomyces yeasts have gained relevance as probiotics, and in vitro and in vivo assays are very promising and offer a research niche with novel applications within the functional food and nutraceutical industry. Several beneficial effects have been described, such as antimicrobial and antioxidant activities and gastrointestinal modulation and regulation functions. In addition, several positive effects of bioactive compounds or production of specific enzymes have been reported on physical, mental and neurodegenerative diseases as well as on the organoleptic properties of the final product. Other points to highlight are the multiomics as a tool to enhance characteristics of interest within the industry; as well as microencapsulation offer a wide field of study that opens the niche of food matrices as carriers of probiotics; in turn, non-Saccharomyces yeasts offer an interesting alternative as microencapsulating cells of various compounds of interest.

Ameliorative Effect of Saccharomyces cerevisiae JKSP39 on Fusobacterium nucleatum and Dextran Sulfate Sodium-Induced Colitis Mouse Model

The aim of this study was to evaluate the ability of the Saccharomyces cerevisiae strain with probiotic properties isolated from Tibetan kefir grains to ameliorate Fusobacterium nucleatum (Fn) infection and dextran sulfate sodium (DSS) treatment-induced murine model of colitis. The tolerance to simulated gastrointestinal conditions, hydrophobicity test, autoaggregation assay, and the antioxidant effect of strains was used to screen one strain with colonization and probiotic potential. The murine model of colitis was established by giving 10⁹ cfu Fn 3 weeks by intragastric administration and 3% DSS in water 1 week before sacrifice. The results indicated that S. cerevisiae JKSP39 (SC) possessed optimal probiotic characteristics in vitro. Supplementation with SC increased the body weight and the expression of anti-inflammatory cytokines (IL-4 and IL-10), while decreasing the disease activity index score and expression of proinflammatory cytokines (TNF-α, IL-6, and IL-17F) in mice undergoing experimental colitis as compared with the colitis model group. Additionally, tight junction proteins and the number of goblet cells per crypt were significantly increased in the SC group, which indicated that the gut barrier was well repaired. The mechanism of SC ameliorating Fn-DSS-induced colitis could be related to the decreased levels of reactive oxygen species (myeloperoxidase, total superoxide dismutase, catalase, H₂O₂, and malondialdehyde) in the colon, the inhibition of endoplasmic reticulum stress, and the regulation of gut microbiota.

Pre-exposure to Candida albicans induce trans-generational immune priming and gene expression of Musca domestica

Insects have the phenomenon of immune priming by which they can have enhanced protection against reinfection with the same pathogen, and this immune protection can be passed on to their offspring, which is defined as “trans-generational immune priming (TGIP).” But whether housefly possesses TGIP is still unclear. Therefore, we used the housefly as the insect model and Candida albicans as the pathogen to explore whether the housefly is capable of eliciting TGIP, and RNA sequencing (RNA-seq) was performed to explore the molecular mechanism of TGIP of the housefly. We found that the housefly possesses TGIP, and adults pre-exposed to heat-killed C. albicans could confer protection to itself and its offspring upon reinfection with a lethal dose of C. albicans. RNA-seq results showed that 30 and 154 genes were differentially expressed after adults were primed with heat-killed C. albicans (CA-A) and after offspring larvae were challenged with a lethal dose of C. albicans (CA-CA-G), respectively. Among the differentially expressed genes (DEGs), there were 23 immune genes, including 6 pattern recognition receptors (PRRs), 7 immune effectors, and 10 immunoregulatory molecules. More importantly, multiple DEGs were involved in the Toll signaling pathway and phagosome signaling pathway, suggesting that the Toll signaling pathway and phagocytosis might play important roles in the process of TGIP of housefly to C. albicans. Our results expanded on previous studies and provided parameters for exploring the mechanism of TGIP.

Beta-Glucan from S. cerevisiae Protected AOM-Induced Colon Cancer in cGAS-Deficient Mice Partly through Dectin-1-Manipulated Macrophage Cell Energy

Although the impacts of Saccharomyces cerevisiae on cancers are mentioned, data on its use in mice with cyclic GMP-AMP synthase deficiency (cGAS-/-) are even rarer. Here, 12 weeks of oral administration of S. cerevisiae protected cGAS-/- mice from azoxymethane (AOM)-induced colon cancers, partly through dysbiosis attenuation (fecal microbiome analysis). In parallel, a daily intralesional injection of a whole glucan particle (WGP; the beta-glucan extracted from S. cerevisiae) attenuated the growth of subcutaneous tumor using MC38 (murine colon cancer cell line) in cGAS-/- mice. Interestingly, the incubation of fluorescent-stained MC38 with several subtypes of macrophages, including M1 (using Lipopolysaccharide; LPS), M2 (IL-4), and tumor-associated macrophages (TAM; using MC38 supernatant activation), could not further reduce the tumor burdens (fluorescent intensity) compared with M0 (control culture media). However, WGP enhanced tumoricidal activities (fluorescent intensity), the genes of M1 pro-inflammatory macrophage polarization (IL-1β and iNOS), and Dectin-1 expression and increased cell energy status (extracellular flux analysis) in M0, M2, and TAM. In M1, WGP could not increase tumoricidal activities, Dectin-1, and glycolysis activity, despite the upregulated IL-1β. In conclusion, S. cerevisiae inhibited the growth of colon cancers through dysbiosis attenuation and macrophage energy activation, partly through Dectin-1 stimulation. Our data support the use of S. cerevisiae for colon cancer protection.

Characterization of cultivable intestinal microbiota in Rhynchophorus palmarum Linnaeus (Coleoptera: Curculionidae) and determination of its cellulolytic activity

Rhynchophorus palmarum Linnaeus is an agricultural pest that affects various palm crops, including coconut (Cocos nucifera) plantations which are prominent in the economy of Northeastern Brazil. Characterization of the intestinal microbiota of R. palmarum, as well as elucidation of aspects related to the biochemistry and physiology of the insect's digestion, is essential for intervention in specific metabolic processes as a form of pest control. Thus, this study aimed to characterize the intestinal microbiota of R. palmarum and investigate its ability to degrade cellulosic substrates, to explore new biological control measures. Intestinal dissection of eight adult R. palmarum insects was performed in a laminar flow chamber, and the intestines were homogenized in sterile phosphate-buffered saline solution. Subsequently, serial dilution aliquots of these solutions were spread on nutritive agar plates for the isolation of bacteria and fungi. The microorganisms were identified by matrix-assisted laser desorption/ionization with a time-of-flight mass spectrometry and evaluated for their ability to degrade cellulose. Fourteen bacterial genera (Acinetobacter, Alcaligenes, Arthrobacter, Bacillus, Citrobacter, Enterococcus, Kerstersia, Lactococcus, Micrococcus, Proteus, Providencia, Pseudomonas, Serratia, and Staphylococcus) and two fungal genera (Candida and Saccharomyces)-assigned to the Firmicutes, Actinobacteria, Proteobacteria, and Ascomycota phyla-were identified. The cellulolytic activity was exhibited by six bacterial and one fungal species; of these, Bacillus cereus demonstrated the highest enzyme synthesis (enzymatic index = 4.6). This is the first study characterizing the R. palmarum intestinal microbiota, opening new perspectives for the development of strategies for the biological control of this insect.

Lactobacillus kefiranofaciens JKSP109 and Saccharomyces cerevisiae JKSP39 isolated from Tibetan kefir grain co-alleviated AOM/DSS induced inflammation and colorectal carcinogenesis

This study aimed to investigate the alleviative effects of Lactobacillus kefiranofaciens JKSP109 (LK) and Saccharomyces cerevisiae JKSP39 (SC) isolated from Tibetan kefir grain on colon inflammation and colorectal carcinogenesis. Azoxymethane (AOM) and dextran sulfate sodium (DSS) were used to establish a mouse model of colorectal cancer (CRC). The treatment group mice were administered with LK, SC, or the combination of LK and SC for five days per week from the day of receiving AOM. The composition of the gut microbiota was assessed using internal transcribed spacer 2 and 16S rRNA gene high-throughput sequencing. Furthermore, the biomarkers associated with gut barrier integrity, inflammation, regulators of cell proliferation, and apoptosis were evaluated. The results showed that the administration of LK, SC, and their combination increased the body weights and decreased the disease activity index (DAI) score and tumor multiplicity. As compared to the CRC model group, the three treatment groups positively regulated the gut microbiota. Meanwhile, the three treatments also enhanced the gut barrier, decreased the expression of proinflammatory cytokines and oncocyte proliferation indicators, and increased the expression of terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive tumor epithelial cells and content of short chain fatty acids in fecal samples. All these results indicated that the LK and SC alleviated the inflammation and colorectal carcinogenesis in AOM/DSS-induced CRC mouse models, and the majority of tested indexes in the combination group were superior to single strain groups.

Is the Intestinal Bacterial Community in the Australian Rabbitfish Siganus fuscescens Influenced by Seaweed Supplementation or Geography?

We recently demonstrated that dietary supplementation with seaweed leads to dramatic improvements in immune responses in S. fuscescens, a candidate species for aquaculture development in Asia. Here, to assess whether the immunostimulatory effect was facilitated by changes to the gut microbiome, we investigated the effects of those same seaweed species and four commercial feed supplements currently used in aquaculture on the bacterial communities in the hindgut of the fish. Since we found no correlations between the relative abundance of any particular taxa and the fish enhanced innate immune responses, we hypothesised that S. fuscescens might have a core microbiome that is robust to dietary manipulation. Two recently published studies describing the bacteria within the hindgut of S. fuscescens provided an opportunity to test this hypothesis and to compare our samples to those from geographically distinct populations. We found that, although hindgut bacterial communities were clearly and significantly distinguishable between studies and populations, a substantial proportion (55 of 174 taxa) were consistently detected across all populations. Our data suggest that the importance of gut microbiota to animal health and the extent to which they can be influenced by dietary manipulations might be species-specific or related to an animals’ trophic level.

Diversity and Functions of Yeast Communities Associated with Insects

Following the concept of the holobiont, insect-microbiota interactions play an important role in insect biology. Many examples of host-associated microorganisms have been reported to drastically influence insect biological processes such as development, physiology, nutrition, survival, immunity, or even vector competence. While a huge number of studies on insect-associated microbiota have focused on bacteria, other microbial partners including fungi have been comparatively neglected. Yeasts, which establish mostly commensal or symbiotic relationships with their host, can dominate the mycobiota of certain insects. This review presents key advances and progress in the research field highlighting the diversity of yeast communities associated with insects, as well as their impact on insect life-history traits, immunity, and behavior.

Early melanoma invasivity correlates with gut fungal and bacterial profiles

BACKGROUND

The microbiome is emerging as a crucial player of the immune checkpoint in cancer. Melanoma is a highly immunogenic tumour, and the gut microbiome composition has been correlated to prognosis and evolution of advanced melanoma and proposed as biomarker for immune checkpoint therapy.

OBJECTIVES

We investigated the gut fungal and bacterial composition in early-stage melanoma and correlated microbial profiles with histopathological features.

METHODS

Bacterial 16S rRNA and fungal ITS region sequencing was performed from faecal samples of patients affected by stage I and II melanoma, and healthy controls. A meta-analysis with gut microbiota data from metastatic melanoma patients was also carried out.

RESULTS

We found a combination of gut fungal and bacterial profiles significantly discriminating M patients from controls. In melanoma patients, we observed an abundance of Prevotella copri and yeasts belonging to the Saccharomycetales order. We found bacterial and fungal community correlated to melanoma invasiveness, whereas specific fungal profile correlated to melanoma regression. Bacteroides was identified as general marker of immunogenicity, being shared by regressive and invasive melanoma. In addition, the bacterial community from stage I and II patients were different in structure and richer than those from metastatic melanoma patients.

CONCLUSIONS

Gut microbiota composition in early-stage melanoma changes along the gradient from in situ to invasive (and metastatic) melanoma. Changes in the microbiota and mycobiota are correlated to the histological features of early-stage melanoma, and to the clinical course and response to immune therapies of advanced stage melanoma, through a direct or indirect immunomodulation.

Potential Probiotic Strains of Saccharomyces and Non-Saccharomyces: Functional and Biotechnological Characteristics

Due to the evident demand for probiotic microorganisms, a growing number of scientific studies have involved the preliminary selection of new strains, but deeper studies for knowing specific functional and biotechnological properties are needed. In the present work, twenty yeasts (Saccharomyces and non-Saccharomyces) with potential probiotic characteristics, selected in previous works, were evaluated. The following assays were realized: adhesion to Caco-2/TC7 cells, prebiotic metabolisms, assimilation of cholesterol, enzymatic and antioxidant activity, and antifungal resistance. In addition, the effect of ultrasonic treatment was evaluated for attenuating the cultures before their possible incorporation into a food or supplement. In all of the cases, the unique commercial probiotic yeast (S. boulardii CNM I-745) was used as positive control. Results show different capabilities depending on the property studied. In general, no Saccharomyces yeasts were better in the adhesion to Caco cells, prebiotic metabolism, and presented higher variability of enzymatic activities. The ones related to cholesterol assimilation and antioxidant capability did not show a marked trend, and with respect to the attenuation process, the Saccharomyces yeasts were more resistant. For selecting the potential probiotic yeasts with better balance among all characteristics, a principal component analysis (PCA) was carried out. The most promising yeasts for use as health-promoting probiotics are Hanseniaspora osmophila 1056 and 1094, Lachancea thermotolerans 1039, and S. cerevisiae 3 and 146.

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.

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.

Identification of Vaginal Microbial Communities Associated with Extreme Cervical Shortening in Pregnant Women

The vaginal microbiota plays a critical role in pregnancy. Bacteria from Lactobacillus spp. are thought to maintain immune homeostasis and modulate the inflammatory responses against pathogens implicated in cervical shortening, one of the risk factors for spontaneous preterm birth. We studied vaginal microbiota in 46 pregnant women of predominantly Caucasian ethnicity diagnosed with short cervix (<25 mm), and identified microbial communities associated with extreme cervical shortening (≤10 mm). Vaginal microbiota was defined by 16S rRNA gene sequencing and clustered into community state types (CSTs), based on dominance or depletion of Lactobacillus spp. No correlation between CSTs distribution and maternal age or gestational age was revealed. CST-IV, dominated by aerobic and anaerobic bacteria different than Lactobacilli, was associated with extreme cervical shortening (odds ratio (OR) = 15.0, 95% confidence interval (CI) = 1.56–14.21; p = 0.019). CST-III (L. iners-dominated) was also associated with extreme cervical shortening (OR = 6.4, 95% CI = 1.32–31.03; p = 0.02). Gestational diabetes mellitus (GDM) was diagnosed in 10/46 women. Bacterial richness was significantly higher in women experiencing this metabolic disorder, but no association with cervical shortening was revealed by statistical analysis. Our study confirms that Lactobacillus-depleted microbiota is significantly associated with an extremely short cervix in women of predominantly Caucasian ethnicity, and also suggests an association between L. iners-dominated microbiota (CST III) and cervical shortening.

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.

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.