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Composition and Diversity of Human Oral Microbiome
Published in Chaminda Jayampath Seneviratne, Microbial Biofilms, 2017
Preethi Balan, Chaminda Jayampath Seneviratne and Wim Crielaard
The term mycobiome represents the fungal component of the microbiome community [48]. Being as low as 0.1% of the total microbiome, the mycobiome is often ignored as a constituent of the microbial community [49]. The term microbiome is often used synonymously to represent exclusively the bacterial component of the community. The pioneering HMP and related research consortium have also entirely focussed on the bacteriome in their publications on human microbiome [50]. However, with the commencement of increased recent studies on the human mycobiome, the recovery of information on fungal species populating the microbiome has become increasing available. High-throughput sequencing technologies have begun to untangle the diversity and dynamics of fungal community and are elucidating their role as commensals and pathogens, similar to their bacterial counterparts. The mycobiome is now regarded to play a vital role in maintaining the structure, metabolism and interactions of the microbiome [51].
The Role of Fecal Microbiota Transplantation in Neurological Diseases
Published in David Perlmutter, The Microbiome and the Brain, 2019
Thomas Borody, John Bienenstock
The gut mycobiome, which encompasses all fungal strains within the gut, is an often-neglected component of the gut microbiome as it has been poorly studied and characterized. The mycobiome plays a significant role, similar to that of the gut microbiota, in maintaining a balanced enteric microbial ecosystem,12,13 and has consequently been implicated in a number of gut-associated neurological and psychiatric diseases.14 It is also increasingly being acknowledged that some individual species of fungi may have beneficial therapeutic effects. For example, Saccharomyces boulardii is well established as a potential probiotic.15,16 Increased production of immunoglobulin A has been observed in mice fed S. boulardii following exposure to C. difficile toxin.17 Furthermore, supernatants from S. boulardii cultures have been shown to inhibit the activation of T and dendritic cells in patients with inflammatory bowel disease (IBD).18 It is possible that fungal strains could extensively modulate the immune system in a variety of ways, including interaction with C-type lectin receptors such as Dectin-1.19 Overgrowth of enteric fungi may occur as a result of antibiotic therapy, and diets high in carbohydrates also influence fungal abundance and diversity.20 Changes in mycobiome have also been associated with the development of human metabolic diseases including obesity and diabetes21,22 psychiatric conditions23 and eating disorders24. Whether these described changes are involved in, or simply associated with, the modulation of these conditions is unclear at present.
Mycobiome in health and disease
Published in Mahmoud A. Ghannoum, John R. Perfect, Antifungal Therapy, 2019
Najla El-Jurdi, Jyotsna Chandra, Pranab K. Mukherjee
The correlation between infection due to the Hepatitis B virus (HBV) and the composition and diversity of the gastrointestinal mycobiome was investigated by Chen et al. [64] in 161 participants including: (1) hepatitis B cirrhosis patients (n = 38), (2) chronic hepatitis B patients (n = 35), (3) HBV carriers (n = 33), and (4) healthy volunteers (n = 55). Both culture-dependent and independent (18S rRNA sequencing) methods were used. As expected, the culture-dependent approach detected Candida species (C. albicans, C. glabrata, C. krusei and C. tropicalis) and S. cerevisiae. The culture-independent method identified 37 operational taxonomic units (OTUs, clusters of nearly-identical sequence tags or phylotypes, commonly used to define microbial taxa) [65] representing different fungi, including: Saccharomyces spp., Penicillium spp., Galactomyces spp., and Cryptococcus spp., results that are in agreement with other studies investigating the gastrointestinal mycobiome [51]. The number of fungi detected was positively correlated with disease progression. Abundance of Candida and Saccharomyces spp. were higher in volunteers with increasing severity of HBV infection. Moreover, patients with HBV-related cirrhosis or chronic HBV infection had greater fungal diversity than HBV carriers and healthy controls. These results confirmed earlier findings regarding the relationship between increasing fungal burden and disease severity in HBV infection [66,67]. A potential link between increase in fungal abundance and HBV infection could be an underlying deficiency in the host immune response. For example, Thomas et al. [68] reported an association between mutation in the mannose binding protein (MBP) and persistent HBV infection in Caucasian patients. This protein is a pattern recognition receptor (PRR) that binds to mannan on fungal cell walls, triggering a host immune response, and, thus, plays a key role in defense against fungal pathogens. It is possible that lack or dysfunction of MBP during HBV infection leads to attenuated defense against fungi, and, thus, results in increased colonization by these pathogens. Further research is required to confirm the underlying mechanisms.
Host-mycobiome metabolic interactions in health and disease
Published in Gut Microbes, 2022
Neelu Begum, Azadeh Harzandi, Sunjae Lee, Mathias Uhlen, David L. Moyes, Saeed Shoaie
Understanding the behaviour of fungi, both individually and as a community, is essential in elucidating the role of the mycobiome in health and disease. Untethering the distinct metabolic interactions and effects of secondary metabolism provide an opportunity for disease intervention, determining the point at which dysbiosis arises, identifying biomarkers for better diagnostics and novel therapeutic targets. Metabolism is a holistic and integrative subject that combines genetics, molecular pathways, signalling and environmental factors. Multi-disciplinary tools and methods such as system biology are needed to develop in silico models as a predictive tool to validate current datasets and knowledge. In doing so, we will generate a platform to answer how mycobiome metabolism affects the host in health and disease.
Supragingival mycobiome and inter-kingdom interactions in dental caries
Published in Journal of Oral Microbiology, 2020
Divyashri Baraniya, Tsute Chen, Anubhav Nahar, Fadhl Alakwaa, Jennifer Hill, Marisol Tellez, Amid Ismail, Sumant Puri, Nezar Noor Al-Hebshi
Despite extensive research on the human oral microbiome, little is known about its fungal component, particularly species belonging to genera other than Candida. This may have been due to the fact that other fungi are present in very low abundance (rare biosphere), in addition to the difficulty in recovering them using culture-based methods [24,25]. Indeed, in this study we found the fungal load in supragingival plaque to be in the range of 4–10 fungi for each 10 million bacteria (i.e. hardly 0.0001%), which is even lower than that found in saliva (0.06%) [26]. Nevertheless, mycobiome analysis revealed the presence of a complex fungal community, consistent with previous reports [6–8]. Several core taxa identified in this study are in common with those studies, including Candida, Malassezia, Cryptococcus, Cladosporium, and Saccharomyces, supporting the presence of an endogenous oral mycobiome.
Preliminary study of the oral mycobiome of children with and without dental caries
Published in Journal of Oral Microbiology, 2019
Jacquelyn M. Fechney, Gina V. Browne, Neeta Prabhu, Laszlo Irinyi, Wieland Meyer, Toby Hughes, Michelle Bockmann, Grant Townsend, Hanieh Salehi, Christina J. Adler
The current study also identified what made up the ‘core’ oral mycobiome in childhood, and found there was a considerable overlap in composition between this and the adult oral mycobiome. In both the children examined herein and previous studies of the adult oral mycobiome [21,22], Candida, Malassezia, Saccharomyces and Cladosporium species were identified as core members. The adult core oral mycobiome was also found to contain Aureobasidium, Cystofilobasidium, Filobasidium and Penicillium species [21,22]. These were identified in the childrens’ plaque samples, however were present in less than 50% of samples and not considered ‘core’ species. R. mucilaginosa was also found to be a core member in the childhood oral mycobiome. This species was amongst the most frequently isolated fungal species in a study examining the oral mycobiome in 40 adults [23].