Hydrocarbon-Contaminated Sites: Is There Something More Than Exophiala xenobiotica? New Insights into Black Fungal Diversity Using the Long Cold Incubation Method

Abstract

Human-made hydrocarbon-rich environments are important reservoirs of microorganisms with specific degrading abilities and pathogenic potential. In particular, black fungi are of great interest, but their presence in the environment is frequently underestimated because they are difficult to isolate. In the frame of a biodiversity study from fuel-contaminated sites involving 30 diesel car tanks and 112 fuel pump dispensers (52 diesel and 60 gasoline, respectively), a total of 181 black fungal strains were isolated. The long cold incubation (LCI) of water-suspended samples, followed by plating on Dichloran Rose Bengal Chloramphenicol Agar (DRBC), gave isolation yields up to six times (6.6) higher than those of direct plating on DRBC, and those of enrichment with a phenolic mix. The sequencing of ITS and LSU-rDNA confirmed the dominance of potentially pathogenic fungi from the family Herpotrichiellaceae and Exophiala xenobiotica. Moreover, other opportunistic species were found, including E. opportunistica, E. oligosperma, E. phaeomuriformis, and Rhinocladiella similis. The recurrent presence of E. crusticola, Knufia epidermidis, Aureobasidium melanogenum, Cladosporium spp., and Scolecobasidium spp. was also recorded. Interestingly, 12% of total isolates, corresponding to 50% of taxa found (16/32), represent new species. All the novel taxa in this study were isolated by LCI. These findings suggest that black fungal diversity in hydrocarbon-rich niches remains largely unexplored and that LCI can be an efficient tool for further investigations.

Black Fungi and Stone Heritage Conservation: Ecological and Metabolic Assays for Evaluating Colonization Potential and Responses to Traditional Biocides

“…dirinae CCFEE 5707, and N. capensis CCFEE 6200), can be considered at least in part to be occasional. A. pullulans is considered, indeed, a generalist that can inhabit different habitats without substantial specialization at the genomic level [54], and E. oligosperma is a well-known opportunist isolated from a number of household environments such as tap water and diesel car tanks [41,55,56]. This confirms the two survival strategies in fungi from extreme environments: they can be either widespread generalists, thriving in both extreme and moderate conditions, or specialists more or less confined to extremes [57][58][59].…”

“…To study them, two main approaches are available: the high throughput sequencing and the traditional culture-based approach. The biomolecular approach has become the dominant method of studying the microbial diversity in the last decade [41]. In fact, the main part of environmental microorganisms are unculturable and the behavior of a single species can frequently be explained in a community context [41].…”

“…The biomolecular approach has become the dominant method of studying the microbial diversity in the last decade [41]. In fact, the main part of environmental microorganisms are unculturable and the behavior of a single species can frequently be explained in a community context [41]. However, beyond the exponentially increasing information, there is not an equally rapid increase in knowledge regarding the mechanisms and the main actors of the deterioration phenomena [42].…”

Response of Poplar and Associated Fungal Endophytic Communities to a PAH Contamination Gradient

“…; OTU55: Phlyctochytrium africanum ; OTU184: Exophiala sp.) as they were already described as potential hydrocarbon degraders [ 46 , 47 , 48 ].…”

The Biodiversity of Microfungi Isolated from the Bark of the Sugar Maple (Acer saccharum)

“…Some species of Exophiala are extremophiles that can grow on rocks and lichens (Harutyunyan et al 2008; or in habitats rich in phenolic hydrocarbons (Isola et al 2021). Various phenols occur in the bark of A. saccharum (St-Pierre et al 2013).…”