A human isolate ofExophiala(Wangiella) dermatitidis forming a catenate synanamorph that links the generaExophialaandCladophialophora

Melanized fungi in human disease

Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Opportunistic, human-pathogenic species in the Herpotrichiellaceae are phenotypically similar to saprobic or phytopathogenic species in the Venturiaceae

Although morphologically similar, species of Cladophialophora (Herpotrichiellaceae) were shown to be phylogenetically distinct from Pseudocladosporium (Venturiaceae), which was revealed to be synonymous with the older genus, Fusicladium. Other than being associated with human disorders, species of Cladophialophora were found to also be phytopathogenic, or to occur as saprobes on organic material, or in water, fruit juices, or sports drinks, along with species of Exophiala. Caproventuria and Metacoleroa were confirmed to be synonyms of Venturia, which has Fusicladium (= Pseudocladosporium) anamorphs. Apiosporina, based on A. collinsii, clustered basal to the Venturia clade, and appears to represent a further synonym. Several species with a pseudocladosporium-like morphology in vitro represent a sister clade to the Venturia clade, and are unrelated to Polyscytalum. These taxa are newly described in Fusicladium, which is morphologically close to Anungitea, a heterogeneous genus with unknown phylogenetic affinity. In contrast to the Herpotrichiellaceae, which were shown to produce numerous synanamorphs in culture, species of the Venturiaceae were morphologically and phylogenetically more uniform. Several new species and new combinations were introduced in Cladophialophora, Cyphellophora (Herpotrichiellaceae), Exophiala, Fusicladium, Venturia (Venturiaceae), and Cylindrosympodium (incertae sedis).

A new species of Cladophialophora (hyphomycetes) from boreal and montane bryophytes

During a survey of bryophilous fungi from boreal and montane habitats in central Alberta, a hitherto undescribed species of Cladophialophora was recovered from Polytrichum juniperinum, Aulacomnium palustre, and Sphagnum fuscum. On potato dextrose agar (PDA) colonies grew slowly, attaining a diameter of 25 mm after 30 d, were dark grey, velvety, radially sulcate, and convolute and cracked at the centre. Micronematous conidiophores gave rise to branched chains of small (1-2 x 8-22 microm), cylindrical to fusiform conidia with truncate, swollen scars at each end. Phylogenies built on the ITS and ribosomal SSU regions indicate the isolates form a monophyletic clade within the family Herpotrichiellaceae (Chaetothyriales) that is composed of two geographically based groups, each with 99% within-group sequence similarity and 97-98% between-group sequence similarity. A teleomorph has not been found but would likely be similar to species of Capronia. In vitro inoculation of the isolates onto axenically grown P. juniperinum produced no discernible host symptoms, and host penetration could not be detected using light microscopy. The production of polyphenol oxidases by the fungus and the role of other Cladophialophora species as latent endophytes and saprobes suggest that a potential role for the fungus is the degradation of the polyphenol-rich cell walls of mosses. A dichotomous key to species of the genus Cladophialophora is provided.

Cerebral phaeohyphomycosis caused by Fonsecaea monophora

We report a case of cerebral phaeohyphomycosis in a 53-year-old immunocompetent diabetic male, caused by Fonsecaea monophora. Computerized tomography of the brain revealed an abscess, which yielded F. monophora in pure culture. The patient's condition deteriorated on treatment with voriconazole and 5-fluorocytosine, and improved subsequently with high-dose itraconazole. The genus Fonsecaea has recently been revised and the new species F. monophora generated from molecular analysis of isolates, most of which were originally identified as Fonsecaea pedrosoi. This is the fourth case of cerebral infection known to have been caused by F. monophora, although only the first reported as such. These cases suggest that the clinical potential of F. monophora differs from that of F. pedrosoi, one of the main agents of chromoblastomycosis, with F. monophora being predominantly neurotropic in the human host.

Fungal biocatalysts in the biofiltration of VOC-polluted air

Gas-phase biofilters used for the treatment of waste gases were originally packed with compost or other natural filter beds containing indigenous microorganisms. Over the past decade much effort has been made to develop new carrier materials, more performant biocatalysts and new types of bioreactors. Elimination capacities reached nowadays are 5 to 10 times higher than those originally reported with conventional compost biofilters. With the recently developed inert filter beds, inoculation is a prerequisite for successful start-up and operation. Either non-defined mixed cultures or pure bacterial cultures have originally been used. The search for efficient fungal biocatalysts started only a few years ago, mainly for the biofiltration of waste gases containing hydrophobic compounds, such as styrene, alpha-pinene, benzene, or alkylbenzenes. In this review, recently isolated new fungal strains able to degrade alkylbenzenes and other related volatile organic pollutants are described, as well as their major characteristics and their use as biocatalysts in gas-phase biofilters for air pollution control. In biofiltration, the most extensively studied organism belongs to the genus Exophiala, although strains of Scedosporium, Paecilomyces, Cladosporium, Cladophialophora, and white-rot fungi are all potential candidates for use in biofilters. Encouraging results were obtained in most of the cases in which some of those organisms were present in gas-phase biofilters. They allow reaching high elimination capacities and are resistant to low pH values and to reduce moisture content.

Phylogenetic relationships of human-pathogenic Cladosporium (Xylohypha) species inferred from partial LS rRNA sequences

The controversy about the appropriate taxonomic placement of agents of subcutaneous and systemic mycoses in either Cladosporium or Xylohypha, both genera characterized by conidia being produced in dry, acropetal chains, was addressed with partial sequencing of LS ribosomal RNA. Observation of catenate anamorphs in species of Capronia (Ascomycotina, Herpotrichiellaceae), a genus which also has anamorphs in Exophiala, suggested the possibility of a close interrelationship of all human-associated taxa. To test this hypothesis, partial sequences of 43 strains of Cladosporium/Xylohypha were analysed. Human-pathogenic and saprophytic Cladosporium species were found to be phylogenetically distinct from each other and, on the basis of known teleomorph relationships, were considered to be anamorphs of Herpotrichiellaceae and Mycosphaerellaceae, respectively. They should therefore be classified in different anamorph-genera; Cladosporium being restricted to plant-associated species. A relatively large proportion of the Herpotrichiellaceae is presumed to be animal-associated. The black yeast genus Exophiala was also confirmed to be of herpotrichiellaceous relationship. The genus Xylohypha is unrelated.