Frontiers in fungal biology最新文献

Introduction and methods: The distribution of tenuazonic acid (TeA), alternariol (AOH), alternariol monomethyl ether (AME), and tentoxin (TEN) between the pulp and peel was determined in different tomato varieties after artificial inoculation with three Alternaria species (Alternaria alternata, Alternaria tenuissima, and Alternaria solani) and incubation for 3 weeks. The role of heat treatments, similar to pasteurization, in their stability was also investigated.

Results and discussion: Unlike AME that was never detected, TeA, AOH, and TEN were determined at different levels in the pulp and peel. Specifically, AOH remained mainly in the peel, where the inoculation was carried out, while TeA and TEN migrated into the pulp and were also found in the discarded liquid accumulated during the incubation period. Heat treatments reduced TeA, AOH, and TEN to varying degrees. In particular, the TeA level was slightly reduced after treatment both at 100°C (approximately 10%) and 121°C (approximately 20%), while a reduction of approximately 30% was achieved after the double heat treatment (treatment at 100°C followed by treatment at 121°C). AOH was found to be less stable to heat treatments, showing a reduction of around 50% after treatment at 100°C and up to 80% after double heating treatments. TEN was reduced by approximately 50% only after the combined treatment of 100°C + 121°C.

Methionine, a key sulfur-containing amino acid, is involved in various important functions in cellular metabolism. Genes that encode enzymes to catalyze steps of the methionine biosynthesis pathway are essential for survival of fungi. The SsMet1 (SS1G_11000) gene in Sclerotinia sclerotiorum is an orthologue of BcStr2, a gene characterized in Botrytis cinerea that plays a key role in methionine biosynthesis. In this study, we characterized SsMet1 in S. sclerotiorum by creating SsMet1-deletion mutants, Met1-2 and Met1-4, using a split marker technique. The SsMet1-deletion mutants were unable to grow on minimal medium and did not produce sclerotia. Supplementation with methionine and homocysteine rescued the defects in mycelial growth, but not sclerotial development of the SsMet1-deletion mutants. These results indicate that SsMet1-deletion mutants are auxotrophic for methionine. In addition, the SsMet1-deletion mutants exhibited increased sensitivity to osmotic and oxidative stresses, cell wall-damaging agents, and thermal stress. The mutants were avirulent on detached bean leaves, but virulence was also restored with methionine supplementation in minimal media. All the defects were restored by genetic complementation of the mutant with wildtype SsMet1 allele. The results of this study indicate that SsMet1 plays a critical role in the regulation of various cellular processes in S. sclerotiorum.

Native yeast strains have been proved to be of great importance for food industry. In the present work, two different Saccharomyces cerevisiae native yeast strains isolated from the must from Moschofilero and Agiorgitiko varieties, respectively, were studied in order to estimate the influence of temperature and ethanol concentration on their proliferation ability via asymmetric flow field-flow fractionation (AsFlFFF) technique. The growth rate of the yeast strains, was directly linked to the biomass production under these conditions and was finally investigated via the ability of AsFlFFF to separate particles according to their size. The experimental results showed that the native yeast Saccharomyces cerevisiae from the must of the Moschofilero variety has an ideal growth temperature of 15°C in the absence of alcohol but exhibits low resistance to ethanol. In contrast, yeasts from the Agiorgitiko variety exhibit resistance to 10% v/v ethanol and remain active for a longer period of time. The ability of these strains to grow under these conditions is a strong indication that they can be used as starter cultures in winemaking to improve the organoleptic characteristics of the produced wines. Yeasts from Moschofilero are suitable for starting fermentation under normal conditions, while yeasts from Agiorgitiko can be used both as starter yeasts and in ethanol environments. This study shows also that the asymmetric flow field-flow fractionation technique can be successfully used to monitor yeast growth under different experimental conditions.

Background: The rising prevalence of nosocomial infections, particularly those caused by airborne fungal spores in operating rooms and intensive care units (ICUs), has become a significant public health concern. Fusarium species in water systems pose a severe threat to immunocompromised patients and can disseminate as aerosols through devices such as faucets and showers. This study aimed to isolate and identify Fusarium species from the water systems of the ICUs and transplant units at Imam Khomeini Hospital Complex and Shariati Hospital in Tehran, Iran, as potential sources of future outbreaks. Additionally, the study sought to determine the in vitro susceptibilities of the isolates to conventional antifungal agents.

Methods: Sterile swabs and open plates containing Sabouraud dextrose agar (SDA) with chloramphenicol were used to collect water samples from sink surfaces, shower trays, faucets, and around the drains of sinks, as well as from bathroom areas. Swab samples were cultured, and the open-plate samples were evaluated for the growth of Fusarium species. The validation of all Fusarium sp. isolates was performed using DNA sequencing of the translation elongation factor 1-alpha (TEF-1α) gene. The antifungal susceptibility patterns of each isolate were tested against voriconazole, itraconazole, posaconazole, caspofungin, and amphotericin B using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method for filamentous fungi.

Results: Fusarium species were recovered from six out of 362 water system samples, representing 1.65% of the total. Five isolates were identified as Fusarium oxysporum from the F. oxysporum complex, while one isolate was identified as Fusarium proliferatum from the Fusarium fujikuroi complex. All isolates were obtained from sinks (three isolates) and faucets (three isolates) at Imam Khomeini Hospital. Antifungal susceptibility testing revealed that posaconazole, voriconazole, and amphotericin B were the most effective drugs against all Fusarium isolates, with no instances of resistance to these antifungal agents observed. However, non-wild-type isolates were noted for the other drugs tested.

Discussion: The isolation of pathogenic Fusarium species from water samples collected in the ICU wards of the Imam Khomeini Hospital Complex underscores the urgent need to implement effective control and prevention measures in hospital water systems.

Temperature-related growth characteristics and wood decay capacities of Biscogniauxia nummularia strains were analysed in vitro, revealing variability between strains. To model the growth characteristics fitted dose-response curves were generated using the four-parameter Brain-Cousens hormesis model. The different strains showed distinct optimum growth temperatures, with some achieving maximum growth at 25°C, while others peaked at 28°C, depending on the tested culture media. Strains tested also exhibited variation in their temperature ranges for measurable growth, with some tolerating a broader range than others. The results of the study lead to the consideration that temperature tolerance as well as the optimal growth temperature might be influenced by the strains' geographic origin, with those from southern Germany possibly adapted to higher temperatures. In terms of wood decay, mass loss caused by the various strains differed clearly in many cases, suggesting potential strain-dependent differences in pathogenicity. Additionally, genetic analysis of the beta-tubulin DNA region of B. nummularia specimens examined revealed considerable variations between the strains.

Ecuador is one of the countries in the world where ticks and tick-borne diseases are major constraints on cattle health and productivity. The intense use of synthetic acaricides to manage tick infestations resulted in widespread acaricide resistance in the tick Rhipicephalus microplus, which is known to infest over 75% of the farms where cattle are raised in the country. Sustainable and environmentally friendly alternatives to control the cattle tick R. microplus are needed urgently. This minireview describes a project at the Santo Domingo Experimental Station of the National Institute of Agricultural Research to develop biopesticides for tick management to exemplify advances in collaborative research on the use of entomopathogenic fungi as active ingredients, or mycopesticides, in formulations to control R. microplus. Research and development conducted in multiple phases revealed the in vitro and in vivo acaricidal properties of B. bassiana sensu lato (s.l.) strain INIAP L3B3. These efforts followed efficacy and safety norms issued by the government agency of Ecuador in charge of controls and regulations to protect an improve animal health, plant health, and food safety. Results described herein indicate that B. bassiana s.l. INIAP L3B3 can be registered as an eco-friendly mycopesticide alternative to synthetic chemical acaricides or could complement conventional chemical acaricide applications for integrated R. microplus management programs in support of sustainable cattle raising in Ecuador.

Introduction: Onion bulbs are edible, nutritious vegetables and spices. In Nigeria, mass propagation of onion seedlings is limited due to infection of the onion bulbs by Aspergillus section Nigri, especially Aspergillus niger strains. Mycotoxin-producing A. niger strains are detrimental to public health. Hence, this study was undertaken to screen the locally sourced onion bulbs for fumonisin B₂ (FB₂) [Multiplex A: fum6 (374 bp), fum8 (272 bp), fum13 (168 bp), and fum19 (479 bp) and Multiplex B: fum1 (452 bp), fum7 (238 bp), fum3 (173 bp), and fum14 (321 bp)] and ochratoxin A [OTA; pks15ks (776 bp)] A. niger biosynthetic genes.

Methods: Thus, 100 onion bulbs were collected from four different local markets (Dugbe, Agbowo, Sasa, and Omi). The surface of each bulb was disinfected, and after incubation, isolates of A. niger were detected. A. niger isolates were cultured on potato dextrose agar. Genomic DNA was extracted from isolates of A. niger. Multiplex PCR confirmed the presence and absence of FB₂ (fum) and OTA (pks15ks) biosynthetic genes.

Results and discussion: A total of 200 isolates of A. niger were isolated from the onion bulbs, and 22 (11%) isolates amplified at least two fum genes, while three (1.5%) amplified the pks15ks gene. All isolates were positive for fum1 and fum19. The highest/lowest percentage of the location/isolates of fum and pks15ks was Agbowo/Omi with 32.0%/2.1% and Dugbe/Agbowo with 6.7%/2.3%, respectively. Hence, the use of multiplex PCR to detect FB₂ and OTA biosynthetic genes in the isolated A. niger strains from the locally sourced onion bulbs will assist onion growers in the mass production of healthy onion seedlings with export potential and quality. Early detection of FB₂ and OTA biosynthetic genes is important to predict possible mycotoxin-producing A. section Nigri in onion bulbs.

Two biological phenomena that contribute to increasing complexity in biological systems are mutualistic symbiotic interactions and the evolution of sociality. These two phenomena are also of fundamental importance to our understanding of the natural world. An organism that poses a threat to one or both of these is therefore also of great interest as it represents a challenge that mutualistic symbioses and social organisms have to overcome. This is the case with the fungus Escovopsis (Ascomycota: Hypocreales), which attacks the fungus garden of attine ants (Formicidae: Attina) such as the leaf cutters. This parasite has attracted much high-profile scientific interest for considerable time, and its study has been fruitful in understanding evolutionary, ecological and behavioural processes. Despite this, much of the biology and ecology of this organism remains unknown. Here we discuss this fungus and three sister genera (Escovopsioides, Luteomyces and Sympodiorosea) that until recently were considered as a single group. We first describe its position as the most highly specialised microbial symbiont in this system other than the mutualistic fungal cultivar itself and as that of greatest scientific interest. We then review the taxonomic history of the group and its macroevolution and biogeography. We examine what we know of its life cycle in the field - surprisingly little is known of how it is transmitted between colonies, but we explain what is known to date. We then review how it interacts with its host(s), first at the level of its direct interaction with the basidiomycete host fungi wherein we show the evidence for it being a mycoparasite; then at the colony level where empirical evidence points towards it being a parasite with a very low virulence or even merely a opportunist. Finally, we offer directions for future research.

Introduction: The genus Colletotrichum comprises numerous fungal species with diverse ecological roles, including plant pathogenic, endophytic, and saprophytic lifestyles. Accurate species identification is crucial for understanding host-pathogen interactions, disease epidemiology, and fungal ecology. However, taxonomic classification within Colletotrichum remains challenging due to genetic complexity and phenotypic plasticity. Conventional approaches such as single-gene analyses and multilocus sequence typing (MLST) frequently fail to resolve closely related taxa, leading to misidentifications that hinder species delimitation and comparative evolutionary studies. Whole-genome sequencing (WGS) offers a promising alternative by providing genome-wide resolution for phylogenetic analysis. This study investigates Colletotrichum isolates associated with the fern Rumohra adiantiformis and evaluates the effectiveness of WGS in addressing taxonomic uncertainties.

Methods: A total of 18 Colletotrichum isolates, including fern-associated strains, were analyzed. Genomic DNA was extracted and sequenced using the Illumina NovaSeq platform. High-quality genome assemblies were generated, and gene prediction was conducted using AUGUSTUS. Orthogroup assignment and phylogenomic analysis were performed based on single-copy orthologs, and phylogenetic trees were constructed using MLST and WGS-based approaches. Comparative analyses were carried out to assess the taxonomic resolution provided by WGS in relation to traditional methods.

Results: Genome-wide phylogenomic analysis revealed distinct evolutionary lineages among Colletotrichum isolates that MLST failed to resolve, highlighting host and geographic differentiation. High-quality genome assemblies were obtained, with 98.3% of genes assigned to orthogroups, indicating strong genomic conservation. Phylogenetic analyses confirmed a close relationship between Rumohra adiantiformis-associated isolates and Colletotrichum filicis, reinforcing the effectiveness of WGS in species identification.

Discussion: These findings demonstrate the superiority of WGS over MLST in resolving species boundaries and reconstructing evolutionary relationships. The enhanced resolution provided by genome-wide data enables more accurate taxonomic classification, reducing misidentifications and improving our understanding of fungal biodiversity. By refining Colletotrichum taxonomy, WGS facilitates ecological and pathogenic studies, offering a robust framework for future research in fungal systematics and plant pathology. As sequencing technologies continue to advance, WGS is expected to become a standard tool for fungal species delineation and evolutionary studies.