Emerging Insights into the Occupational Mycobiome

Abstract

Purpose of Review The evolution of molecular-based methods over the last two decades has provided new approaches to identify and characterize fungal communities or “mycobiomes” at resolutions previously not possible using traditional hazard identification methods. The recent focus on fungal community assemblages within indoor environments has provided renewed insight into overlooked sources of fungal exposure. In occupational studies, internal transcribed spacer (ITS) region sequencing has recently been utilized in a variety of environments ranging from indoor office buildings to agricultural commodity and harvesting operations. Recent Findings Fungal communities identified in occupational environments have been primarily placed in the phylum Ascomycota and included classes typically identified using traditional fungal exposure methods such as the Eurotiomycetes, Dothideomycetes, Sordariomycetes, and Saccharomycetes. The phylum Basidiomycota has also been reported to be more prevalent than previously estimated and ITS region sequences have been primarily derived from the classes Agaricomycetes and Ustilaginomycetes. These studies have also resolved sequences placed in the Basidiomycota classes Tremellomycetes and Exobasidiomycetes that include environmental and endogenous yeast species. Summary These collective datasets have shown that occupational fungal exposures include a much broader diversity of fungi than once thought. Although the clinical implications for occupational allergy are an emerging field of research, establishing the mycobiome in occupational environments will be critical for future studies to determine the complete spectrum of worker exposures to fungal bioaerosols and their impact on worker health.

The Domestic Environment and the Lung Mycobiome

“…Previous culture-based studies showed a higher prevalence of Aspergillus and Penicillium [20][21][22]42], which are traditionally the most expected genus in indoors environments. It seems that this is a bias of culture-based procedures as our results are coincident with other molecular approaches [24,43,56]. Nevertheless, Penicillium polonicum and two species of Aspergillus (A. subversicolor and A. flavus) were detected in 50% (6/12) and 33.3% (4/12) of the samples from houses and the genera were also cultured.…”

“…Among the filamentous fungi, Aureobasidium was isolated in 70% of the houses, and Penicillium, Aspergillus, Alternaria, and Cladosporium were present in 40% to 60% of the 20 houses and Cladosporium showed the highest number of colonies detected (Supplemental material cultures). All these genera were also the genus Cryptococcus and Malassezia as highly present in indoor environments [23,24,40,43]. The work of Green et al [23] specifically described 41% of the fungal microbiota inside a building as members of Basidiomycota and 55% of Ascomycota species, which is almost the same distribution detected in the houses of our patients.…”

“…Perhaps its presence in other studies is somehow hidden under the Cryptococcus spp. Group, which is described in different works [13,23,24,40].…”

“…Several culture-based studies have attempted to demonstrate the link between asthmatic crises in children and the presence of fungal components in the air of their homes [20][21][22]. More recently, some studies have approached the same objective through various molecular methods by studying the mycobiome of environments at work [23][24][25]. Most of these studies have shown that the lung mycobiome mainly proceeds from inhaled air and oral cavity mycobiota [26].…”

Potential occupational and respiratory hazards in a Minnesota cannabis cultivation and processing facility

“…Internal transcribed spacer region sequencing revealed fungal taxa commonly detected in occupational environments . Basidiomycota and Agaricomycetes were the most frequently identified fungal sequences in general area samples collected at the Minnesota facility, accounting for 20% of all fungal sequences.…”