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Povzetek: The fungal genus Wallemia of the order Wallemiales (Wallemiomycotina, Basidiomycota) comprises the most xerotolerant, xerophilic and also halophilic species worldwide. Wallemia spp. are found in various osmotically challenged environments, such as dry, salted, or highly sugared foods, dry feed, hypersaline waters of solar salterns, salt crystals, indoor and outdoor air, and agriculture aerosols. Recently, eight species were recognized for the genus Wallemia, among which four are commonly associated with foods: W. sebi, W. mellicola, W. muriae and W. ichthyophaga. To date, only strains of W. sebi, W. mellicola and W. muriae have been reported to be related to human health problems, as either allergological conditions (e.g., farmer’s lung disease) or rare subcutaneous/cutaneous infections. Therefore, this allergological and infective potential, together with the toxins that the majority of Wallemia spp. produce even under saline conditions, defines these fungi as filamentous food-borne pathogenic fungi.
Ključne besede: food, air, pathogen, xerophile, halophile, mycotoxin, farmerʼs lung disease, subcutaneous infection
Objavljeno v DiRROS: 06.08.2024; Ogledov: 21; Prenosov: 24
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Povzetek: Numerous agents of infections in humans and other mammals are found among fungi that are able to survive extreme environmental conditions and to quickly adapt to novel habitats. Nevertheless, the relationship between opportunistic potential and polyextremotolerance was not yet studied systematically in fungi. Here, the link between polyextremotol- erance and opportunistic pathogenicity is shown in a kingdom-wide phylogenetic analysis as a statistically significant co- occurrence of extremotolerance (e.g. osmotolerance and psychrotolerance) and opportunism at the level of fungal orders. In addition to extremotolerance, fungal opportunists share another characteristic%an apparent lack of specialised virulence traits. This is illustrated by a comparative genomic analysis of 20 dothideomycetous and eurotiomycetous black fungi. While the genomes of specialised fungal plant pathogens were significantly enriched in known virulence-associated genes that encode secreted proteases, carbohydrate active enzyme families, polyketide synthases, and non-ribosomal peptide synthetases, no such signatures were observed in human opportunists. Together the presented results have several implications. If infection of human hosts is a side effect of fungal stress tolerance and adaptability, the human body is most likely neither the preferred habitat of such species, nor important for their evolutionary success. This defines opportunism as opposed to pathogenicity, where infection is advantageous for the species% fitness. Since opportunists are generally incapable of the host-to-host transmission, any host-specific adaptations are likely to be lost with the resolution of the infection, explaining the observed lack of specialised virulence traits. In this scenario opportunistic infections should be seen as an evolutionary dead end and unlikely to lead to true pathogenicity.
Ključne besede: fungi, pathogenicity, infections in humans
Objavljeno v DiRROS: 24.07.2024; Ogledov: 85; Prenosov: 3334
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Povzetek: One of the most commonly encountered species in the small basidiomycetous sub-phylum Wallemiomycotina is Wallemia mellicola, a xerotolerant fungus with a widespread distribution. To investigate the population characteristics of the species, whole genomes of twenty-five strains were sequenced. Apart from identification of four strains of clonal origin, the distances between the genomes failed to reflect either the isolation habitat of the strains or their geographical origin. Strains from different parts of the world appeared to represent a relatively homogenous and widespread population. The lack of concordance between individual gene phylogenies and the decay of linkage disequilibrium indicated that W. mellicola is at least occasionally recombining. Two versions of a putative mating-type locus have been found in all sequenced genomes, each present in approximately half of the strains. W. mellicola thus appears to be capable of (sexual) recombination and shows no signs of allopatric speciation or specialization to specific habitats.
Ključne besede: population genomics, halotolerance, xerotolerance, basidiomycete, allergenic fungus, recombination
Objavljeno v DiRROS: 23.07.2024; Ogledov: 113; Prenosov: 55
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Povzetek: The fungus Phyllosticta citricarpa is a quarantine pathogen in the EU and is of high economic importance in many parts of the world where favourable climate conditions drive the development of citrus black spot (CBS) disease. Disease symptoms include necrotic lesions on leaves and fruits. Low disease pressure can reduce crop market-ability, while higher disease pressure can cause premature fruit drop, significantly increasing crop losses. The wind-dispersed spores of P. citricarpa are especially prob-lematic for rapid pathogen dispersal, but also provide an opportunity for early detec-tion of the disease spreading into a new area. In this study we have developed and validated a quantitative PCR (qPCR) assay based on the TEF1-α sequence. Specificity testing demonstrated that it is currently the only qPCR assay that does not cross- react with closely related Phyllosticta species. The assay is sensitive and can detect a single copy of the TEF1 gene in a reaction, it is highly repeatable and reproducible and can be used for testing of the sticky tapes from spore traps as well as citrus fruit sam-ples. High-throughput sequencing (HTS) of the DNA barcodes ITS1 and TEF1 was also explored for the detection and discrimination of P. citricarpa. The limit of detection of the HTS was 1000 spores on a daily spore trap tape. This study makes an important improvement to the diagnostics of the CBS and the methods developed can also be applied to improve the surveillance and early detection of the pathogen when linked to spore samplers in the field.
Ključne besede: detection, fungal spore sampling, internal transcribed region (ITS), translation elongation factor 1-α (TEF1)
Objavljeno v DiRROS: 12.07.2024; Ogledov: 118; Prenosov: 137
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Ključne besede: common hazel, Turkish hazel, powdery mildew
Objavljeno v DiRROS: 28.02.2023; Ogledov: 677; Prenosov: 300
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