The various forms of interactions that microorganisms engage in within fermented foods result in distinct metabolic product patterns. Fermentation products often feature both yeasts and bacteria, each possessing characteristics that can enhance the overall quality of the food, thus benefiting consumers. Kefir, a fermented milk originating from grains containing a unique and intricate blend of bacteria and yeasts living in a symbiotic relationship, is a valuable model for studying the evolution of the interactions between yeasts and bacteria. Targeted metagenomics was applied to investigate the microbiome of a batch of traditional Romanian kefir and further examine the growth and metabolic properties of the dominant yeast and bacterial strains isolated from this batch. In contrast to yeast, which is either unaffected or harmed by the presence of bacteria, our study revealed that a specific strain of Lactobacillus (L. rhamnosus) derived from the kefir batch benefited from the presence of Saccharomyces cerevisiae. The analysis of short-chain fatty acids (SCFAs) produced by in vitro cultures of these two chosen strains indicated significant changes in SCFA levels compared to single cultures. The dynamic interactions described in this and other studies on kefir emphasize the importance of a more profound comprehension of the ecological mechanisms governing interactions between yeast, bacterial, and mammalian cells.

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.

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

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

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.