Osmoregulation and the human mycobiome

Characterizing the Human Mycobiota: A Comparison of Small Subunit rRNA, ITS1, ITS2, and Large Subunit rRNA Genomic Targets

Interest in the human microbiome has increased dramatically in the last decade. However, much of this research has focused on bacteria, while the composition and roles of their fungal counterparts remain less understood. Furthermore, a variety of methodological approaches have been applied, and the comparability between studies is unclear. This study compared four primer pairs targeting the small subunit (SSU) rRNA (18S), ITS1, ITS2, and large subunit (LSU) rRNA (26S) genomic regions for their ability to accurately characterize fungal communities typical of the human mycobiota. All four target regions of 21 individual fungal mock community taxa were capable of being amplified adequately and sequenced. Mixed mock community analyses revealed marked variability in the ability of each primer pair to accurately characterize a complex community. ITS target regions outperformed LSU and SSU. Of the ITS regions, ITS1 failed to generate sequences for Yarrowia lipolytica and all three Malassezia species when in a mixed community. These findings were further supported in studies of human sinonasal and mouse fecal samples. Based on these analyses, previous studies using ITS1, SSU, or LSU markers may omit key taxa that are identified by the ITS2 marker. Of methods commonly used in human mycobiota studies to date, we recommend selection of the ITS2 marker. Further investigation of more recently developed fungal primer options will be essential to ultimately determine the optimal methodological approach by which future human mycobiota studies ought to be standardized.

Examining the gut bacteriome, virome, and mycobiome in glucose metabolism disorders: Are we on the right track?

Human gut microbiome is defined as the gene complement of the gut microbial community, measured via laboratory metagenomic techniques. It includes bacteriome, virome and mycobiome, which represent, respectively, the assemblages of bacteria, viruses and fungi, living in the human gut. Gut microbiota function as a living "organ" that interacts with the gastro-intestinal environment, provides nutrients and vitamins to the organism and transduces hormonal messages, essentially influencing the main metabolic pathways, including drug metabolism. A clear association between gut, and glucose metabolism disorders has recently emerged. Medications acting on glucose absorption in the gut, or enhancing gut hormone activity are already extensively employed in the therapy of diabetes. Moreover, the gut is characterized by immune, and autonomous neuronal features, which play a critical role in maintaining glucose metabolism homeostasis. Gut microbes respond to neuroendocrine, and immune biochemical messages, affecting the health, and behavior of the host. There is vast heterogeneity in the studies included in this review, hence a meta-analysis, or a systematic review were not applicable. In this article, we attempt to reveal the interplay between human gut microbiota physiology, and hyperglycemic states, synthesizing, and interpreting findings from human studies.