Speleomycology of Air in Stopica Cave (Serbia).

Fungi can colonize organic matter present in subterranean sites and have a significant role as dwellers in different microniches of cave habitats. In order to analyze the content of airborne fungal propagules in different parts of "Stopica Cave," a touristic site in Serbia, air sampling was carried out in three seasons during 2020, prior to and during the onset of COVID-19 pandemic. Culturable mycobiota was identified using both microscopic techniques and ITS region/BenA gene barcoding, while multivariate analyses were employed to establish the link between fungal taxa and different environmental factors. The maximal measured fungal propagule concentrations were recorded during spring sampling which were based on fungal propagule concentration categories; the cave environment matches the category V. A total of 29 fungal isolates were identified, while Aspergillus, Cladosporium, Fusarium, Lecanicillium, Mucor, and Penicillium were the most diverse genera. According to the trophic mode, most of the isolated fungal species were pathotrophs (75.86%), but when regarding ecological guilds, the most dominant were undefined saprobes and animal pathogens (41.38% for each). Show caves are especially vulnerable to human impacts, and the fungal propagules' concentration within the caves could be good indices for the level of ecological disturbance.

Longitudinal alterations of the gut mycobiota and microbiota on COVID-19 severity.

BACKGROUND: The impact of SARS-CoV-2 infection on the gut fungal (mycobiota) and bacterial (microbiota) communities has been elucidated individually. This study analyzed both gut mycobiota and microbiota and their correlation in the COVID-19 patients with severe and mild conditions and follow-up to monitor their alterations after recovery. METHODS: We analyzed the gut mycobiota and microbiota by bacterial 16S and fungal ITS1 metagenomic sequencing of 40 severe patients, 38 mild patients, and 30 healthy individuals and reanalyzed those of 10 patients with severe COVID-19 approximately 6 months after discharge. RESULTS: The mycobiota of the severe and mild groups showed lower diversity than the healthy group, and in some, characteristic patterns dominated by a single fungal species, Candida albicans, were detected. Lower microbial diversity in the severe group was observed, but no differences in its diversity or community structure were detected between the mild and healthy groups. The microbiota of the severe group was characterized by an increase in Enterococcus and Lactobacillus, and a decrease in Faecalibacterium and Bacteroides. The abundance of Candida was positively correlated with that of Enterococcus in patients with COVID-19. After the recovery of severe patients, alteration of the microbiota remained, but the mycobiota recovered its diversity comparable to that of mild and healthy groups. CONCLUSION: In mild cases, the microbiota is stable during SARS-CoV-2 infection, but in severe cases, alterations persist for 6 months after recovery.

The faecal metabolome in COVID-19 patients is altered and associated with clinical features and gut microbes.

Although SARS-CoV-2 can invade the intestine, though its effect on digestion and absorption is not fully understood. In the present study, 56 COVID-19 patients and 47 age- and sex-matched healthy subjects were divided into a discovery cohort and a validation cohort. Blood, faeces and clinical information were collected from the patients in the hospital and at discharge. The faecal metabolome was analysed using gas chromatography-mass spectrometry, and Spearman's correlation analyses of clinical features, the serum metabolome, and the faecal micro- and mycobiota were conducted. The results showed that, the faeces of COVID-19 patients were enriched with important nutrients that should be metabolized or absorbed, such as sucrose and 2-palmitoyl-glycerol; diet-related components that cannot be synthesized by humans, such as 1,5-anhydroglucitol and D-pinitol; and harmful metabolites, such as oxalate, were also detected. In contrast, purine metabolites such as deoxyinosine and hypoxanthine, low-water-soluble long-chain fatty alcohols/acids such as behenic acid, compounds rarely occurring in nature such as D-allose and D-arabinose, and microbe-related compounds such as 2,4-di-tert-butylphenol were depleted in the faeces of COVID-19 patients. Moreover, these metabolites significantly correlated with altered serum metabolites such as oxalate and gut microbesincluding Ruminococcaceae, Actinomyces, Sphingomonas and Aspergillus. Although levels of several faecal metabolites, such as sucrose, 1,5-anhydroglucitol and D-pinitol, of discharged patients were not different from those of healthy controls (HCs), those of oxalate and 2-palmitoyl-glycerol did differ. Therefore, alterations in the faecal metabolome of COVID-19 patients may reflect malnutrition and intestinal inflammation and warrant greater attention. The results of present study provide new insights into the pathogenesis and treatment of COVID-19.