The gut mycobiota of rural and urban individuals is shaped by geography

Intraneoplastic fungal dysbiosis is associated with colorectal cancer progression and host gene mutation

BACKGROUND

The relationship between intraneoplastic fungi and colorectal cancer (CRC) progression remains largely unclear. Here, we investigated fungal community changes in adenoma and CRC and their correlation with host genetic mutations.

METHODS

We obtained 261 tissue biopsies from two geographically distinct cohorts of CRC and adenoma patients, with each individual contributing 2-5 biopsies from lesions and 2 from adjacent normal tissues. 18S ribosomal RNA gene sequencing was used for microbial profiling. Host genetic alterations including KRAS mutations and microsatellite instability (MSI) were detected concurrently.

FINDINGS

Intra-neoplastic fungal composition significantly differed between CRC and adenoma in two independent cohorts, with enrichment of highly variable fungi (HVF) in CRC. Six HVFs exhibited higher abundances in adenoma and CRC compared to adjacent normal tissues with Malassezia showing a progressive increase from adenoma to CRC. Fungi intratumoral heterogeneity index also increased from adenoma through stages I to IV of CRC. Intra-tumoral fungi-fungi co-abundance analysis indicated stronger positive interactions in CRC than in adenoma, with increasingly robust links among intra-tumoral fungi along adenoma-CRC progression, primarily driven by Malassezia and Aspergillus. Furthermore, fungal heterogeneity was significantly correlated with host genetic mutations, with higher risk indices in CRC tissues harboring KRAS and MSI mutations. Thirteen fungi stratified CRC samples with KRAS mutations, achieving an area under the curve (AUC) of 0.86, while those associated with MSI status showed an AUC of 0.89.

INTERPRETATION

This study demonstrates that intraneoplastic fungal community alterations occur between adenoma and CRC, with increasing heterogeneity associated with host genetic mutations, emphasizing the role of fungal dysbiosis in CRC.

FUNDING

This work was supported by RGC Research Impact Fund Hong Kong (R4032-21F); RGC-CRF (C4008-23W); Strategic Seed Funding Collaboration Research Scheme CUHK (3133344); Strategic Impact Enhancement Fund CUHK (3135509); Impact case for RAE CUHK (3134277).

Comparing the impact of landscape on the gut microbiome of Apis mellifera in Atlantic Forest and Caatinga Biomes

The composition of the gut microbiota in animals can be influenced by a variety of intrinsic and extrinsic factors in the host, such as diet, physiological state, and genetics. This study aimed to compare the structural composition of the gut microbiota of Apis mellifera bees from two distinct Brazilian biomes, the Atlantic Forest and the Caatinga, using high throughput 16 S rRNA sequencing. We identified a core microbiota composed of seven genera present in all samples: Lactobacillus, Commensalibacter, Rhizobiaceae, Snodgrassella, Gilliamella, Orbaceae and Bifidobacterium. These taxa accounted for 63% of all bacterial genera in the dataset. Interestingly, we observed a significantly differential abundance of the genus Apibacter between bees from the two biomes, with a marked increase in bees from Atlantic Forest. However, the overall variance in the gut structural composition attributable to landscape type, while significant, was relatively low. Notably, none of the members of the core microbiota were differently abundant between the biomes. Understanding the magnitude of landscape-associated effects on the microbiota of bees in different biomes is crucial for the accurate assessment of the impact of anthropogenic factors. These findings provide important insights into the resilience and adaptability of the honey bee gut microbiome across contrasting environments, contributing to the development of conservation and sustainable management strategies for these essential pollinators.

Gut microbiota and their metabolites in the immune response of rheumatoid arthritis: Therapeutic potential and future directions

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent joint inflammation, damage, and loss of function. In recent years, the role of gut microbiota and its metabolites in immune regulation has attracted increasing attention. The gut microbiota influences the host immune system's homeostasis through various mechanisms, regulating the differentiation, function, and immune tolerance of immune cells. Dysbiosis of the gut microbiota in RA patients is closely associated with abnormal activation of immune cells and excessive secretion of inflammatory cytokines. Metabolites produced by the gut microbiota, such as short-chain fatty acids (SCFAs), tryptophan metabolites, bile acids, and amino acid metabolites, play a critical role in immune responses, regulating the functions of immune cells like T cells, B cells, and macrophages, and inhibiting the release of pro-inflammatory cytokines. Restoring the balance of the gut microbiota and optimizing the production of metabolic products may become a new strategy for RA treatment. This review discusses the role of gut microbiota and its metabolites in the immune response of RA, exploring how they influence the immunopathological process of RA through the regulation of immune cells and key immune factors. It also provides a theoretical basis for future therapeutic strategies based on gut microbiota modulation.

Normal Gut Microbiomes in Diverse Populations: Clinical Implications

The human microbiome is a sensor and modulator of physiology and homeostasis. Remarkable tractability underpins the promise of therapeutic manipulation of the microbiome. However, the definition of a normal or healthy microbiome has been elusive. This is in part due to the underrepresentation of minority groups and major global regions in microbiome studies to date. We review studies of the microbiome in different populations and highlight a commonality among health-associated microbiome signatures along with major drivers of variation. We also provide an overview of microbiome-associated therapeutic interventions for some widespread, widely studied diseases. We discuss sources of bias and the challenges associated with defining population-specific microbiome reference bases. We propose a roadmap for defining normal microbiome references that can be used for population-customized microbiome therapeutics and diagnostics.

Impact of urbanization on gut microbiome mosaics across geographic and dietary contexts

This study provides a comprehensive assessment of how urban-rural divides influence gut microbial diversity and composition across the distinct geographical landscapes of Kazakhstan, elucidating the intricate interplay between lifestyle, environment, and gut microbiome. In this prospective cohort study, we enrolled 651 participants from urban centers and rural settlements across Kazakhstan, following ethical approval and informed consent. Comprehensive demographic, dietary, and stool sample data were collected. 16S rRNA gene sequencing and shotgun metagenomics techniques were employed to delineate the intricate patterns of the gut microbiome. A rigorous statistical framework dissected the interplay between urbanization gradients, geography, dietary lifestyles, and microbial dynamics. Our findings demonstrate a stark microbial divide between urban and rural gut ecosystems. The study found significant differences in gut microbiome diversity and composition between urban and rural populations in Kazakhstan. Urban microbiomes exhibited reduced diversity, higher Firmicutes/Bacteroidetes ratios, and increased prevalence of genera Coprococcus and Parasutterella. In contrast, rural populations had greater microbial diversity and abundance of Ligilactobacillus, Sutterella, and Paraprevotella. Urbanization also influenced dietary patterns, with urban areas consuming more salt, cholesterol, and protein, while rural areas had diets richer in carbohydrates and fiber. The study also identified distinct patterns in the prevalence of antibiotic resistance genes and virulence factors between urban and rural gut microbiomes. This study sheds light on how urbanization may be deeply involved in shaping the intricate mosaic of the gut microbiome across Kazakhstan's diverse geographical and dietary landscapes, underscoring the complex interplay between environmental exposures, dietary lifestyles, and the microbial residents inhabiting our intestines.

IMPORTANCE

The study examined gut microbiome composition across diverse geographical locations in Kazakhstan, spanning urban centers and rural settlements. This allows for thoroughly investigating how urbanization gradients and geographic factors shape the gut microbiome. The study's examination of the gut resistome and prevalence of virulence-associated genes provide essential insights into the public health implications of urbanization-driven microbiome alterations. Collecting comprehensive demographic, dietary, and stool sample data enables the researchers to better understand the relationships between urbanization, nutritional patterns, and gut microbiome composition. The findings have important implications for understanding how urbanization-driven microbiome changes may impact human health and well-being, paving the way for tailored interventions to restore a balanced gut microbial ecology.

Neonatal Gut Mycobiome: Immunity, Diversity of Fungal Strains, and Individual and Non-Individual Factors

The human gastrointestinal ecosystem, or microbiome (comprising the total bacterial genome in an environment), plays a crucial role in influencing host physiology, immune function, metabolism, and the gut-brain axis. While bacteria, fungi, viruses, and archaea are all present in the gastrointestinal ecosystem, research on the human microbiome has predominantly focused on the bacterial component. The colonization of the human intestine by microbes during the first two years of life significantly impacts subsequent composition and diversity, influencing immune system development and long-term health. Early-life exposure to pathogens is crucial for establishing immunological memory and acquired immunity. Factors such as maternal health habits, delivery mode, and breastfeeding duration contribute to gut dysbiosis. Despite fungi's critical role in health, particularly for vulnerable newborns, research on the gut mycobiome in infants and children remains limited. Understanding early-life factors shaping the gut mycobiome and its interactions with other microbial communities is a significant research challenge. This review explores potential factors influencing the gut mycobiome, microbial kingdom interactions, and their connections to health outcomes from childhood to adulthood. We identify gaps in current knowledge and propose future research directions in this complex field.

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.

Fermented foods: Harnessing their potential to modulate the microbiota-gut-brain axis for mental health

Over the past two decades, whole food supplementation strategies have been leveraged to target mental health. In addition, there has been increasing attention on the ability of gut microbes, so called psychobiotics, to positively impact behaviour though the microbiota-gut-brain axis. Fermented foods offer themselves as a combined whole food microbiota modulating intervention. Indeed, they contain potentially beneficial microbes, microbial metabolites and other bioactives, which are being harnessed to target the microbiota-gut-brain axis for positive benefits. This review highlights the diverse nature of fermented foods in terms of the raw materials used and type of fermentation employed, and summarises their potential to shape composition of the gut microbiota, the gut to brain communication pathways including the immune system and, ultimately, modulate the microbiota-gut-brain axis. Throughout, we identify knowledge gaps and challenges faced in designing human studies for investigating the mental health-promoting potential of individual fermented foods or components thereof. Importantly, we also suggest solutions that can advance understanding of the therapeutic merit of fermented foods to modulate the microbiota-gut-brain axis.

Documenting the diversity of the Namibian Ju|'hoansi intestinal microbiome

We investigate the bacterial and fungal composition and functionality of the Ju|'hoansi intestinal microbiome (IM). The Juǀ'hoansi are a hunter-gatherer community residing in northeastern Namibia. They formerly subsisted by hunting and gathering but have been increasingly exposed to industrial dietary sources, medicines, and lifestyle features. They present an opportunity to study the evolution of the human IM in situ, from a predominantly hunter-gatherer to an increasingly Western urban-forager-farmer lifestyle. Their bacterial IM resembles that of typical hunter-gatherers, being enriched for genera such as Prevotella, Blautia, Faecalibacterium, Succinivibrio, and Treponema. Fungal IM inhabitants include animal pathogens and plant saprotrophs such as Fusarium, Issatchenkia, and Panellus. Our results suggest that diet and culture exert a greater influence on Ju|'hoansi IM composition than age, self-identified biological sex, and medical history. The Ju|'hoansi exhibit a unique core IM composition that diverges from the core IMs of other populations.

Gut mycobiome alterations in obesity in geographically different regions

The gut fungi play important roles in human health and are involved in energy metabolism. This study aimed to examine gut mycobiome composition in obese subjects in two geographically different regions in China and to identify specific gut fungi associated with obesity. A total of 217 subjects from two regions with different urbanization levels [Hong Kong (HK): obese, n = 59; lean, n = 59; Kunming (KM): obese, n = 50; lean, n = 49. Mean body mass index (BMI) for obesity = 33.7] were recruited. We performed deep shotgun metagenomic sequencing on fecal samples to compare gut mycobiome composition and trophic functions in lean and obese subjects across these two regions. The gut mycobiome of obese subjects in both HK and KM were altered compared to those of lean subjects, characterized by a decrease in the relative abundance of Nakaseomyces, Schizosaccharomyces pombe, Candida dubliniensis and an increase in the abundance of Lanchanceathermotolerans, Saccharomyces paradox, Parastagonospora nodorum and Myceliophthorathermophila. Reduced fungal - bacterial and fungal - fungal correlations as well as increased negative fungal-bacterial correlations were observed in the gut of obese subjects. Furthermore, the anti-obesity effect of fungus S. pombe was further validated using a mouse model. Supplementing high-fat diet-induced obese mice with the fungus for 12 weeks led to a significant reduction in body weight gain (p < 0.001), and an improvement in lipid and glucose metabolism compared to mice without intervention. In conclusion, the gut mycobiome composition and functionalities of obese subjects were altered. These data shed light on the potential of utilizing fungus-based therapeutics for the treatment of obesity. S. pombe may serve as a potential fungal probiotic in the prevention of diet-induced obesity and future human trials are needed.

Recent progress in plant-derived polysaccharides with prebiotic potential for intestinal health by targeting gut microbiota: a review

Natural products of plant origin are of high interest and widely used, especially in the food industry, due to their low toxicity and wide range of bioactive properties. Compared to other plant components, the safety of polysaccharides has been generally recognized. As dietary fibers, plant-derived polysaccharides are mostly degraded in the intestine by polysaccharide-degrading enzymes secreted by gut microbiota, and have potential prebiotic activity in both non-disease and disease states, which should not be overlooked, especially in terms of their involvement in the treatment of intestinal diseases and the promotion of intestinal health. This review elucidates the regulatory effects of plant-derived polysaccharides on gut microbiota and summarizes the mechanisms involved in targeting gut microbiota for the treatment of intestinal diseases. Further, the structure-activity relationships between different structural types of plant-derived polysaccharides and the occurrence of their prebiotic activity are further explored. Finally, the practical applications of plant-derived polysaccharides in food production and food packaging are summarized and discussed, providing important references for expanding the application of plant-derived polysaccharides in the food industry or developing functional dietary supplements.

The eukaryome of African children is influenced by geographic location, gut biogeography, and nutritional status

Eukaryotes have historically been studied as parasites, but recent evidence suggests they may be indicators of a healthy gut ecosystem. Here, we describe the eukaryome along the gastrointestinal tract of children aged 2-5 years and test for associations with clinical factors such as anaemia, intestinal inflammation, chronic undernutrition, and age. Children were enrolled from December 2016 to May 2018 in Bangui, Central African Republic and Antananarivo, Madagascar. We analyzed a total of 1104 samples representing 212 gastric, 187 duodenal, and 705 fecal samples using a metabarcoding approach targeting the full ITS2 region for fungi, and the V4 hypervariable region of the 18S rRNA gene for the overall eukaryome. Roughly, half of all fecal samples showed microeukaryotic reads. We find high intersubject variability, only a handful of taxa that are likely residents of the gastrointestinal tract, and frequent co-occurrence of eukaryotes within an individual. We also find that the eukaryome differs between the stomach, duodenum, and feces and is strongly influenced by country of origin. Our data show trends towards higher levels of Fusarium equiseti, a mycotoxin producing fungus, and lower levels of the protist Blastocystis in stunted children compared to nonstunted controls. Overall, the eukaryome is poorly correlated with clinical variables. Our study is of one of the largest cohorts analyzing the human intestinal eukaryome to date and the first to compare the eukaryome across different compartments of the gastrointestinal tract. Our results highlight the importance of studying populations across the world to uncover common features of the eukaryome in health.

Longitudinal gut mycobiota changes in Japanese infants during first three years of life

Although fungi can have a large impact on host health through the stimulation of the immune system and toxin production, few studies have investigated the gut mycobiota during infancy, a period during which sensitivity to internal and external stimuli is high. To capture the trend in fungal colonization during infancy, we evaluated the gut mycobiota of ten Japanese infants during the first 3 years of life. Infants had two major phyla, Ascomycota (68.9%) and Basidiomycota (29.6%), and the most abundant genus was Saccharomyces (26.8%), followed by Malassezia (18.5%), Candida (12.3%), Meyerozyma (8.5%), and Penicillium (8.3%). Alpha diversity analysis revealed a significant decrease in fungal richness and evenness with age, suggesting adaptive selection of the colonizing species in the gut environment. Beta diversity analysis divided infant mycobiota into age-related clusters and showed discrete separation before and after weaning, suggesting shift in microenvironment via weaning. In the initial stage, a variety of fungal species that likely originated from an environment, such as Malassezia spp., was highly colonized and were replaced by yeasts, such as Saccharomyces, after weaning. Further studies are needed to shed light on how the passage of the series of fungal colonizations in infancy affects the development of the host immune system and the other homeostasis involved in health later in life.

Fungal-Bacterial Interactions in the Human Gut of Healthy Individuals

Most studies of the microbiota in the human gut focus on the bacterial part, but increasing information shows that intestinal fungi are also important for maintaining health. This can be either by directly influencing the host or by indirectly influencing the gut bacteria that link to host health. Studies of fungal communities in large cohorts are scarce; therefore, this study aims at obtaining more insight into the mycobiome of healthy individuals and how this mycobiome interacts with the bacterial component of the microbiome. For this purpose, ITS2 and 16S rRNA gene amplicon sequencing was performed on fecal samples from 163 individuals which were available from two separate studies to analyze the fungal and bacterial microbiome, respectively, as well as the cross-kingdom interactions. The results showed a much lower fungal, as compared to bacterial, diversity. Ascomycota and Basidiomycota were the dominant fungal phyla across all the samples, but levels varied enormously between individuals. The ten most abundant fungal genera were Saccharomyces, Candida, Dipodascus, Aureobasidium, Penicillium, Hanseniaspora, Agaricus, Debaryomyces, Aspergillus, and Pichia, and here also extensive inter-individual variation was observed. Correlations were made between bacteria and fungi, and only positive correlations were observed. One of the correlations was between Malassezia restricta and the genus Bacteroides, which have both been previously described as alleviated in IBD. Most of the other correlations found were with fungi that are not known as gut colonizers but originate from food and the environment. To further investigate the importance of the observed correlations found, more research is needed to discriminate between gut colonizers and transient species.

Esophageal mycobiome landscape and interkingdom interactions in esophageal squamous cell carcinoma

Background

The study purpose was to characterize the mycobiome and its associations with the expression of pathogenic genes in esophageal squamous cell carcinoma (ESCC).

Methods

Patients with primary ESCC were recruited from two central hospitals. We performed internal transcribed spacer 1 (ITS1) ribosomal DNA sequencing analysis. We compared differential fungi and explored the ecology of fungi and the interaction of bacteria and fungi.

Results

The mycobiota diversity was significantly different between tumors and tumor-adjacent samples. We further analysed the differences between the two groups, at the species level, confirming that Rhodotorula toruloides, Malassezia dermatis, Hanseniaspora lachancei, and Spegazzinia tessarthra were excessively colonized in the tumor samples, whereas Preussia persica, Fusarium solani, Nigrospora oryzae, Acremonium furcatum, Golovinomyces artemisiae, and Tausonia pullulans were significantly more abundant in tumor-adjacent samples. The fungal co-occurrence network in tumor-adjacent samples was larger and denser than that in tumors. Similarly, the more complex bacterial-fungal interactions in tumor-adjacent samples were also detected. The expression of mechanistic target of rapamycin kinase was positively correlated with the abundance of N. oryzae and T. pullulans in tumor-adjacent samples. In tumors, the expression of MET proto-oncogene, receptor tyrosine kinase (MET) had a negative correlation and a positive correlation with the abundance of R. toruloides and S. tessarthra, respectively.

Conclusion

This study revealed the landscape of the esophageal mycobiome characterized by an altered fungal composition and bacterial and fungal ecology in ESCC.

Role of gastrointestinal microbial populations, a terra incognita of the human body in the management of intestinal bowel disease and metabolic disorders

Intestinal bowel disease (IBD) is a chronic immune-mediated clinical condition that affects the gastrointestinal tract and is mediated by an inflammatory response. Although it has been extensively studied, the multifactorial aetiology of this disorder makes it difficult to fully understand all the involved mechanisms in its development and therefore its treatment. In recent years, the fundamental role played by the human microbiota in the pathogenesis of IBD has been emphasised. Microbial imbalances in the gut bacterial communities and a lower species diversity in patients suffering from inflammatory gastrointestinal disorders compared to healthy individuals have been reported as principal factors in the development of IBD. These served to support scientific arguments for the use of probiotic microorganisms in alternative approaches for the prevention and treatment of IBD. In a homeostatic environment, the presence of bacteria (including probiotics) on the intestinal epithelial surface activates a cascade of processes by which immune responses inhibited and thereby commensal organisms maintained. At the same time these processes may support activities against specific pathogenic bacteria. In dysbiosis, these underlying mechanisms will serve to provoke a proinflammatory response, that, in combination with the use of antibiotics and the genetic predisposition of the host, will culminate in the development of IBD. In this review, we summarised the main causes of IBD, the physiological mechanisms involved and the related bacterial groups most frequently associated with these processes. The intention was to enable a better understanding of the interaction between the intestinal microbiota and the host, and to suggest possibilities by which this knowledge can be useful for the development of new therapeutic treatments.

Fungal diversity in the gut microbiome of young South African children

BACKGROUND

The fungal microbiome, or mycobiome, is a poorly described component of the gut ecosystem and little is known about its structure and development in children. In South Africa, there have been no culture-independent evaluations of the child gut mycobiota. This study aimed to characterise the gut mycobiota and explore the relationships between fungi and bacteria in the gut microbiome of children from Cape Town communities.

METHODS

Stool samples were collected from children enrolled in the TB-CHAMP clinical trial. Internal transcribed spacer 1 (ITS1) gene sequencing was performed on a total of 115 stool samples using the Illumina MiSeq platform. Differences in fungal diversity and composition in relation to demographic, clinical, and environmental factors were investigated, and correlations between fungi and previously described bacterial populations in the same samples were described.

RESULTS

Taxa from the genera Candida and Saccharomyces were detected in all participants. Differential abundance analysis showed that Candida spp. were significantly more abundant in children younger than 2 years compared to older children. The gut mycobiota was less diverse than the bacterial microbiota of the same participants, consistent with the findings of other human microbiome studies. The variation in richness and evenness of fungi was substantial, even between individuals of the same age. There was significant association between vitamin A supplementation and higher fungal alpha diversity (p = 0.047), and girls were shown to have lower fungal alpha diversity (p = 0.003). Co-occurrence between several bacterial taxa and Candida albicans was observed.

CONCLUSIONS

The dominant fungal taxa in our study population were similar to those reported in other paediatric studies; however, it remains difficult to identify the true core gut mycobiota due to the challenges set by the low abundance of gut fungi and the lack of true gut colonising species. The connection between the microbiota, vitamin A supplementation, and growth and immunity warrants exploration, especially in populations at risk for micronutrient deficiencies. While we were able to provide insight into the gut mycobiota of young South African children, further functional studies are necessary to explain the role of the mycobiota and the correlations between bacteria and fungi in human health.

Smokeless tobacco consumption induces dysbiosis of oral mycobiome: a pilot study

Smokeless tobacco (SLT) alters the oral microbiome of smokeless tobacco users. Dysbiosis of oral bacteriome has been determined; however, the mycobiome of SLT users has not been characterized. The oral mycobiome was assayed by amplification and sequencing of the fungal internal transcribed spacer (ITS1) region from oral swab samples of non-SLT users, SLT users (with or without oral lesions), and SLT with alcohol users. We observed that the richness and diversity of oral mycobiome were significantly decreased in SLT with oral lesions users than in non-users. The β-diversity analysis showed significant dissimilarity of oral mycobiome between non-users and SLT with oral lesions users. Linear discriminant analysis effect size and random forest analysis of oral mycobiome affirm that the genus Pichia was typical for SLT with oral lesions users. Prevalence of the fungal genus Pichia correlates positively with Starmerella, Mortierella, Fusarium, Calonectria, and Madurella, but is negatively correlated with Pyrenochaeta, Botryosporium, and Alternaria. Further, the determination of oral mycobiome functionality showed a high abundance of pathotroph-saprotroph-symbiotroph and animal pathogen-endophyte-epiphyte-undefined saprotroph at trophic and guild levels, respectively, indicating possibly major changes in normal growth repression of types of fungi. The oral mycobiome in SLT users was identified and comprehensively analyzed for the first time. SLT intake is associated with oral mycobiome dysbiosis and such alterations of the oral mycobiome may contribute to oral carcinogenesis in SLT users. This study will provide a basis for further large-scale investigations on the potential role of the mycobiome in SLT-induced oral cancer. KEY POINTS: • SLT induces dysbiosis of the oral microbiome that can contribute to oral cancer. • Oral mycobiome diversity is noticeably reduced in SLT users having oral lesions. • Occurrence of Pichia can be used as a biomarker for SLT users having oral lesions.

Mycobiota composition and changes across pregnancy in patients with gestational diabetes mellitus (GDM)

The gut mycobiota has never been studied either during pregnancy or in patients with gestational diabetes (GDM). This study aimed to analyze the fecal mycobiota of GDM patients during the second (T2) and third (T3) trimester of pregnancy and to compare it with the mycobiota of pregnant normoglycemic women (controls). Forty-one GDM patients and 121 normoglycemic women were studied. GDM mycobiota was composed almost exclusively by the Ascomycota phylum; Basidiomicota accounted for 43% of the relative frequency of the controls. Kluyveromyces (p < 0.001), Metschnikowia (p < 0.001), and Pichia (p < 0.001) showed a significantly higher frequency in GDM patients, while Saccharomyces (p = 0.019), were more prevalent in controls. From T2 to T3, a reduction in fungal alpha diversity was found in GDM patients, with an increase of the relative frequency of Candida, and the reduction of some pro-inflammatory taxa. Many associations between fungi and foods and nutrients were detected. Finally, several fungi and bacteria showed competition or co-occurrence. Patients with GDM showed a predominance of fungal taxa with potential inflammatory effects when compared to normoglycemic pregnant women, with a marked shift in their mycobiota during pregnancy, and complex bacteria-fungi interactions.

Mycobiome-Host Coevolution? The Mycobiome of Ancestral Human Populations Seems to Be Different and Less Diverse Than Those of Extant Native and Urban-Industrialized Populations

Few data exist on the human gut mycobiome in relation to lifestyle, ethnicity, and dietary habits. To understand the effect of these factors on the structure of the human gut mycobiome, we analyzed sequences belonging to two extinct pre-Columbian cultures inhabiting Puerto Rico (the Huecoid and Saladoid) and compared them to coprolite samples found in Mexico and Ötzi, the Iceman’s large intestine. Stool mycobiome samples from extant populations in Peru and urban cultures from the United States were also included. The ancient Puerto Rican cultures exhibited a lower fungal diversity in comparison to the extant populations. Dissimilarity distances showed that the Huecoid gut mycobiome resembled that from ancient Mexico. Fungal genera including Aspergillus spp., Penicillium spp., Rasamsonia spp., Byssochlamys spp., Talaromyces spp., Blastomyces spp., Monascus spp., and Penicilliopsis spp. were differentially abundant in the ancient and extant populations. Despite cultural differences, certain fungal taxa were present in all samples. These results suggest that culture and diet may impact the gut mycobiome and emphasize that modern lifestyles could be associated with the alteration of gut mycobiome diversity. The present study presents data on ancient and extant human gut mycobiomes in terms of lifestyle, ethnicity, and diet in the Americas.

The Neglected Gut Microbiome: Fungi, Protozoa, and Bacteriophages in Inflammatory Bowel Disease

The gut microbiome has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Studies suggest that the IBD gut microbiome is less diverse than that of the unaffected population, a phenomenon often referred to as dysbiosis. However, these studies have heavily focused on bacteria, while other intestinal microorganisms-fungi, protozoa, and bacteriophages-have been neglected. Of the nonbacterial microbes that have been studied in relation to IBD, most are thought to be pathogens, although there is evidence that some of these species may instead be harmless commensals. In this review, we discuss the nonbacterial gut microbiome of IBD, highlighting the current biases, limitations, and outstanding questions that can be addressed with high-throughput DNA sequencing methods. Further, we highlight the importance of studying nonbacterial microorganisms alongside bacteria for a comprehensive view of the whole IBD biome and to provide a more precise definition of dysbiosis in patients. With the rise in popularity of microbiome-altering therapies for the treatment of IBD, such as fecal microbiota transplantation, it is important that we address these knowledge gaps to ensure safe and effective treatment of patients.

Fungal allergic sensitisation in young rural Zimbabwean children: Gut mycobiome and seroreactivity characteristics

Background

The prevalence of allergic diseases has increased over the last few decades, with sensitisation to fungal allergens and gut microbiome dysbiosis implicated in this trend. The fungal community in the gut (mycobiome) has yet to be characterised and related to fungal allergic sensitisation. Thus, we characterised the gut mycobiome and related it to fungal sensitisation and seroreactivity among Zimbabwean children. We further determined the effect of host age, sex, Schistosoma haematobium infection and mycobiome composition on fungal sensitisation and seroreactivity.

Methods

Using shotgun metagenomic sequencing, we characterised the gut microbiome of stool samples of 116 preschool aged children (PSAC) (≤5 years old, 57(49.1%) male and 59 (50.9%) female). Sensitisation to common fungi in Zimbabwe was assessed using skin prick tests (SPTs). Allergen-specific IgM, IgA, IgG, IgE and IgG4 antibodies were quantified by ELISA. We analysed the relationship between fungal genera and SPT reactivity by ANOVA; fungal genera and IgE antibody reactivity by linear regression; variation in mycobiome abundance with host and environmental factors by PERMANOVA; SPT reactivity and host and environmental factors by logistic regression; seroreactivity and host and environmental factors by ANOVA.

Results

The mycobiome formed <1% of the sequenced gut microbiome and 228 fungal genera were identified. The most abundant genera detected were Protomyces, Taphrina, and Aspergillus. S.haematobium infection had a significant effect on fungal genera. Prevalence of SPT sensitisation to ≥1 fungal species was 96%, and individuals were frequently sensitised to Saccharomyces cerevisiae. Antibodies were detected in 100% of the population. There was no relationship between mycobiome abundance and IgE titres or IgE/IgG4 ratios for each fungal species; no significant differences between SPT reactivity and abundance of fungal species except for S. cerevisiae; and fungal seroreactivity did not significantly differ with age. There were some sex (m>f for, Epicoccum nigrum and Penicillium chrysogenum) and SPT reactivity -related differences in seroreactivity.

Conclusion

This is the first comprehensive characterisation of gut mycobiome and fungal allergic sensitisation of rural children in Zimbabwe. Although reported allergic disease is low there is a high percentage of sensitisation. Further studies with larger populations are required to understand the role of the mycobiome in allergic diseases.

Intestinal mycobiota composition and changes in children with thalassemia who underwent allogeneic hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) alters the diversity of the intestinal bacterial microbiota. This study aimed to evaluate human mycobiota composition pre-HSCT and post-HSCT in children with thalassemia.

METHOD

Ten children with thalassemia undergoing allogeneic HSCT were enrolled. The stool samples were collected before the transplantation regimen, before the transplant day, and +15, +30 days, and three months after transplantation. Stool samples were also collected from the donor and the patient's caregivers. Gut mycobiota composition was evaluated with metagenomic analysis.

RESULTS

Pretransplant mycobiota of children with thalassemia (the predominant genus was Saccharomyces, 64.1%) has been shown to approximate the diverse mycobiota compositions of healthy adult donors but becomes altered (lower diversity) following transplant procedures. Three months after HSCT, phyla Ascomycota and Basidiomycota were 83.4% and 15.6%, respectively. The predominant species were Saccaharomyces_uc and Saccharomyces cerevisiae (phylum Ascomycota); we also observed Malassezia restricta and Malassezia globosa (phylum Basidiomycota) (∼13%). On day 90 after HSCT, we observed 65.3% M. restricta and 18.4% M. globosa predominance at the species level in a four-year-old boy with acute graft-versus-host disease (GVHD) (skin and gut involvement) 19 days after transplantation included.

CONCLUSION

The mycobiota composition of children with thalassemia altered after HSCT. We observed Malassezia predominance in a child with GVHD. Further studies in children with GVHD will identify this situation.

Diversity Scaling Analysis of Chinese Gut Microbiomes Across Ethnicities and Lifestyles

Diversity scaling (changes) of human gut microbiome is important because it measures the inter-individual heterogeneity of diversity and other important parameters of population-level diversity. Understanding the heterogeneity of microbial diversity can be used as a reference for the personalized medicine of microbiome-associated diseases. Similar to diversity per se, diversity scaling may also be influenced by host factors, especially lifestyles and ethnicities. Nevertheless, this important topic regarding Chinese populations has not been addressed, to our best knowledge. Here, we fill the gap by applying a recent extension to the classic species–area relationship (SAR), i.e., diversity–area relationship (DAR), to reanalyze a large dataset of Chinese gut microbiomes covering the seven biggest Chinese ethnic groups (covering > 95% Chinese) living rural and urban lifestyles. Four DAR profiles were constructed to investigate the diversity scaling, diversity overlap, potential maximal diversity, and the ratio of local to global diversity of Chinese gut microbiomes. We discovered the following: (i) The diversity scaling parameters (z) at various taxon levels are little affected by either ethnicity or lifestyles, as exhibited by less than 0.5% differences in pairwise comparisons. (ii) The maximal accrual diversity (potential diversity) exhibited difference in only about 5% of pairwise comparisons, and all of the differences occurred in ethnicity comparisons (i.e., lifestyles had no effects). (iii) Ethnicity seems to have stronger effects than lifestyles across all taxon levels, and this may reflect the reality that China has been experiencing rapid urbanization in the last few decades, while the ethnic-related genetic background may change relatively little during the same period.

Dynamic Changes of the Fungal Microbiome in Alcohol Use Disorder

BACKGROUND

Alcohol-associated liver disease (ALD) is an important cause of morbidity and mortality worldwide. The intestinal microbiota is involved in the development and progression of ALD; however, little is known about commensal fungi therein.

METHODS

We studied the dynamic changes of the intestinal fungal microbiome, or mycobiome, in 66 patients with alcohol use disorder (AUD) and after 2 weeks of alcohol abstinence using internal transcribed spacer 2 (ITS2) amplicon sequencing of fecal samples.

RESULTS

Patients with AUD had significantly increased abundance of the genera Candida, Debaryomyces, Pichia, Kluyveromyces, and Issatchenkia, and of the species Candida albicans and Candida zeylanoides compared with control subjects. Significantly improved liver health markers caspase-cleaved and intact cytokeratin 18 (CK18-M65) levels and controlled attenuation parameter (CAP) in AUD patients after 2 weeks of alcohol abstinence were associated with significantly lower abundance of the genera Candida, Malassezia, Pichia, Kluyveromyces, Issatchenkia, and the species C. albicans and C. zeylanoides. This was mirrored by significantly higher specific anti-C. albicans immunoglobulin G (IgG) and M (IgM) serum levels in AUD patients in relation to control participants, and significantly decreased anti-C. albicans IgG levels in AUD subjects after 2 weeks of abstinence. The intestinal abundance of the genus Malassezia was significantly higher in AUD subjects with progressive liver disease compared with non-progressive liver disease.

CONCLUSION

In conclusion, improved liver health in AUD patients after alcohol abstinence was associated with lower intestinal abundances of Candida and Malassezia, and lower serum anti-C. albicans IgG levels. Intestinal fungi might serve as a therapeutic target to improve the outcome of patients in ALD.

Comparative Analysis of Fecal Microbiota of Grazing Mongolian Cattle from Different Regions in Inner Mongolia, China

Simple Summary

Recently, there has been increasing attention focused on the intestinal microflorae of animals due to their critical role in maintaining health and preventing disease. With the improvement of the Chinese national economy and the people’s material standard of living, the beef cattle industry is growing rapidly to meet the growing market demand for beef. Mongolian cattle is a precious genetic resource in China and an excellent cattle breed in Inner Mongolia. However, updated research on topics concerning the gut microbiota of Mongolian cattle are absent. Therefore, this study focused on the differences in the gut microbiota composition of Mongolian cattle in different geographical environments. The gut microbiota composition of the Mongolian cattle from the grasslands was relatively similar, while that from the desert areas was different. The results of this study contribute to our understanding of the influence of geographical factors on the composition of gut microbiota in Mongolian cattle.

Abstract

Mongolian cattle from China have strong adaptability and disease resistance. We aimed to compare the gut microbiota community structure and diversity in grazing Mongolian cattle from different regions in Inner Mongolia and to elucidate the influence of geographical factors on the intestinal microbial community structure. We used high throughput 16S rRNA sequencing to analyze the fecal microbial community and diversity in samples from 60 grazing Mongolian cattle from Hulunbuir Grassland, Xilingol Grassland, and Alxa Desert. A total of 2,720,545 high-quality reads and sequences that were 1,117,505,301 bp long were obtained. Alpha diversity among the three groups showed that the gut microbial diversity in Mongolian cattle in the grasslands was significantly higher than that in the desert. The dominant phyla were Firmicutes and Bacteroidetes, whereas Verrucomicrobia presented the highest abundance in the gut of cattle in the Alxa Desert. The gut bacterial communities in cattle from the grasslands versus the Alxa Desert were distinctive, and those from the grasslands were closely clustered. Community composition analysis revealed significant differences in species diversity and richness. Overall, the composition of the gut microbiota in Mongolian cattle is affected by geographical factors. Gut microbiota may play important roles in the geographical adaptations of Mongolian cattle.

Non-Celiac Gluten/Wheat Sensitivity: Clinical Characteristics and Microbiota and Mycobiota Composition by Response to the Gluten Challenge Test

The aims of this observational “proof-of-concept” study were to analyze the clinical/psychological characteristics and gut microbiota/mycobiota composition of individuals with suspected non-celiac gluten/wheat sensitivity (NCGS/WS) according to responses to the double-blind-placebo-controlled (DBPC) crossover gluten challenge test. Fifty individuals with suspected NCGS/WS were subjected to the DBPC challenge test; anthropometric measurements, psychometric questionnaires, and fecal samples were collected. Twenty-seven (54%) participants were gluten responsive (NCGS), and 23 were placebo responsive, with an order effect. NCGS individuals displayed a significantly lower risk of eating disorders and a higher mental health score when compared to placebo-responsive participants, confirmed by multiple logistic regression analyses (OR = 0.87; 95% CI 0.76–0.98, p = 0.021, and OR = 1.30; 95% CI 1.06–1.59, p = 0.009, respectively). Principal coordinate analyses based on microbiota composition showed a separation by the DBPC response (p = 0.039). For Bacteroides (p = 0.05) and Parabacteroides (p = 0.007), the frequency of amplicon sequence variants was lower, and that for Blautia (p = 0.009) and Streptococcus (p = 0.004) was higher in NCGS individuals at multiple regression analyses. No difference in the mycobiota composition was detected between the groups. In conclusion, almost half of the individuals with suspected gluten sensitivity reported symptoms with placebo; they showed lower mental health scores, increased risk for eating disorders, and a different gut microbiota composition.