Azole resistance in Aspergillus fumigatus- comprehensive review

Aspergillus fumigatus is a ubiquitous filamentous fungus commonly found in the environment. It is also an opportunistic human pathogen known to cause a range of respiratory infections, such as invasive aspergillosis, particularly in immunocompromised individuals. Azole antifungal agents are widely used for the treatment and prophylaxis of Aspergillus infections due to their efficacy and tolerability. However, the emergence of azole resistance in A. fumigatus has become a major concern in recent years due to their association with increased treatment failures and mortality rates. The development of azole resistance in A. fumigatus can occur through both acquired and intrinsic mechanisms. Acquired resistance typically arises from mutations in the target enzyme, lanosterol 14-α-demethylase (Cyp51A), reduces the affinity of azole antifungal agents for the enzyme, rendering them less effective, while intrinsic resistance refers to a natural resistance of certain A. fumigatus isolates to azole antifungals due to inherent genetic characteristics. The current review aims to provide a comprehensive overview of azole antifungal resistance in A. fumigatus, discusses underlying resistance mechanisms, including alterations in the target enzyme, Cyp51A, and the involvement of efflux pumps in drug efflux. Impact of azole fungicide uses in the environment and the spread of resistant strains is also explored.

Chitin-induced disease resistance in plants: A review

Chitin is composed of N-acetylglucosamine units. Chitin a polysaccharide found in the cell walls of fungi and exoskeletons of insects and crustaceans, can elicit a potent defense response in plants. Through the activation of defense genes, stimulation of defensive compound production, and reinforcement of physical barriers, chitin enhances the plant's ability to defend against pathogens. Chitin-based treatments have shown efficacy against various plant diseases caused by fungal, bacterial, viral, and nematode pathogens, and have been integrated into sustainable agricultural practices. Furthermore, chitin treatments have demonstrated additional benefits, such as promoting plant growth and improving tolerance to abiotic stresses. Further research is necessary to optimize treatment parameters, explore chitin derivatives, and conduct long-term field studies. Continued efforts in these areas will contribute to the development of innovative and sustainable strategies for disease management in agriculture, ultimately leading to improved crop productivity and reduced reliance on chemical pesticides.

RNA-Seq-Based Transcriptome Analysis of Nitric Oxide Scavenging Response in Neurospora crassa

While the biological role of naturally occurring nitric oxide (NO) in filamentous fungi has been uncovered, the underlying molecular regulatory networks remain unclear. In this study, we conducted an analysis of transcriptome profiles to investigate the initial stages of understanding these NO regulatory networks in Neurospora crassa, a well-established model filamentous fungus. Utilizing RNA sequencing, differential gene expression screening, and various functional analyses, our findings revealed that the removal of intracellular NO resulted in the differential transcription of 424 genes. Notably, the majority of these differentially expressed genes were functionally linked to processes associated with carbohydrate and amino acid metabolism. Furthermore, our analysis highlighted the prevalence of four specific protein domains (zinc finger C2H2, PLCYc, PLCXc, and SH3) in the encoded proteins of these differentially expressed genes. Through protein-protein interaction network analysis, we identified eight hub genes with substantial interaction connectivity, with mss-4 and gel-3 emerging as possibly major responsive genes during NO scavenging, particularly influencing vegetative growth. Additionally, our study unveiled that NO scavenging led to the inhibition of gene transcription related to a protein complex associated with ribosome biogenesis. Overall, our investigation suggests that endogenously produced NO in N. crassa likely governs the transcription of genes responsible for protein complexes involved in carbohydrate and amino acid metabolism, as well as ribosomal biogenesis, ultimately impacting the growth and development of hyphae.

Chemodiversity and Anti-Leukemia Effect of Metabolites from Penicillium setosum CMLD 18

Penicillium setosum represents a Penicillium species recently described, with little up-to-date information about its metabolic and biological potential. Due to this scenario, we performed chemical and biological studies of P. setosum CMLD18, a strain isolated from Swinglea glutinosa (Rutaceae). HRMS-MS guided dereplication strategies and anti-leukemia assays conducted the isolation and characterization of six compounds after several chromatographic procedures: 2-chloroemodic acid (2), 2-chloro-1,3,8-trihydroxy-6- (hydroxymethyl)-anthraquinone (7), 7-chloroemodin (8), bisdethiobis(methylthio)acetylaranotine (9), fellutanine C (10), and 4-methyl-5,6-diihydro-2H-pyran-2-one (15). From the assayed metabolites, (10) induced cellular death against Kasumi-1, a human leukemia cell line, as well as good selectivity for it, displaying promising cytotoxic activity. Here, the correct NMR signal assignments for (9) are also described. Therefore, this work highlights more detailed knowledge about the P. setosum chemical profile as well as its biological potential, offering prospects for obtaining natural products with anti-leukemia capabilities.

Inactivation and subsequent reactivation of Aspergillus species by the combination of UV and monochloramine: Comparisons with UV/chlorine

Ultraviolet (UV)/monochloramine (NH₂Cl) as an advanced oxidation process was firstly applied for Aspergillus spores inactivation. This study aims to: i) clarify the inactivation and photoreactivation characteristics of UV/NH₂Cl process, ii) compared with UV/Cl₂ in inactivation efficiency, photoreactivation and energy consumption. The results illustrated that UV/NH₂Cl showed better inactivation efficiency than that of UV alone and UV/Cl₂, and could effectively control the photoreactivation. For instance, the inactivation rates for Aspergillus flavus, Aspergillus niger and Aspergillus fumigatus in the processes of UV/NH₂Cl (2.0 mg/L) was 0.034, 0.030 and 0.061 cm²/mJ, respectively, which were higher than that of UV alone (0.027, 0.026 and 0.024 cm²/mJ) and UV/Cl₂ (0.023, 0.026 and 0.031 cm²/mJ). However, there was no synergistic effect for Aspergillus flavus and Aspergillus fumigatus. As for Aspergillus niger, the best synergistic effect can reach 1.86-log₁₀. This may be due to their different resistance to disinfectants, which were related to the size, an outer layer of rodlets (hydrophobins) and pigments. After UV/NH₂Cl inactivation, the degree of cell membrane damage and intracellular reactive oxygen species were higher than that of UV alone. UV/NH₂Cl had the advantages of high inactivation efficiency and inhibition of photoreactivation, which provides a new entry point for the disinfection of waterborne fungi.

Six Main Contributing Factors to High Levels of Mycotoxin Contamination in African Foods

Africa is one of the regions with high mycotoxin contamination of foods and continues to record high incidences of liver cancers globally. The agricultural sector of most African countries depends largely on climate variables for crop production. Production of mycotoxins is climate-sensitive. Most stakeholders in the food production chain in Africa are not aware of the health and economic effects of consuming contaminated foods. The aim of this review is to evaluate the main factors and their degree of contribution to the high levels of mycotoxins in African foods. Thus, knowledge of the contributions of different factors responsible for high levels of these toxins will be a good starting point for the effective mitigation of mycotoxins in Africa. Google Scholar was used to conduct a systemic search. Six factors were found to be linked to high levels of mycotoxins in African foods, in varying degrees. Climate change remains the main driving factor in the production of mycotoxins. The other factors are partly man-made and can be manipulated to become a more profitable or less climate-sensitive response. Awareness of the existence of these mycotoxins and their economic as well as health consequences remains paramount. The degree of management of these factors regarding mycotoxins varies from one region of the world to another.

The role of filamentous fungi in advancing the development of a sustainable circular bioeconomy

Human activities generate enormous amounts of organic wastes and residues. Filamentous fungi (FF) are able to grow on a broad range of substrates and survive over a wide spectrum of growth conditions. These characteristics enable FF to be exploited in biorefineries for various waste streams. Valorization of food industry byproducts into biomass and various arrays of value-added products using FF creates promising pathways toward a sustainable circular economy. This approach might also contribute to reaching the sustainable development goals set by the United Nations, particularly for zero hunger as well as affordable and clean energy. This paper presents the application of filamentous fungi in food, feeds, fuels, biochemicals, and biopolymers. The nutritional values, health benefits, and safety of foods derived from byproducts of food industries are also addressed. The technoeconomical feasibilities, sustainability aspects and challenges and future perspectives for biorefineries using filamentous fungi are discussed.

The aggregation of Aspergillus spores and the impact on their inactivation by chlorine-based disinfectants

The formation of fungal biofilm goes through some different states, including monodisperse state, aggregated state, germinated state, hyphal and biofilm. The aggregation of spores is a primary step of fungal biofilm development in aquatic systems. Previous studies on the inactivation of fungi were mostly performed in the monodisperse state of fungal spores and biofilm state, however, the inactivation of aggregated fungal spores is still unclear. In this study, the aggregated characteristics of fungal spores (Aspergillus fumigatus and Aspergillus flavus) at different pH values were firstly studied, and the inactivation efficiency of fungal spores at different aggregation degree by chlorine-based disinfectants was also clarified. The results showed that the aggregation degree of Aspergillus fumigatus was the highest at pH 9.0 while it was the lowest at pH 5.0. Aggregation between fungal spores was mainly mediated by occasional adhesin-adhesin interactions and electrostatic interactions. Compared with monodisperse spores, fungal spores were more resistant to chlorine-based disinfectants with the increase of spore aggregation degree. The inactivation rate constants of Aspergillus fumigatus at 30% and 63% aggregation degree were 1.5- and 4-folds lower than that of monodisperse spores, respectively. The lower proportion of membrane damage and higher intracellular reactive oxygen species level for aggregated spores than monodisperse spores was observed according to the flow cytometric results after chlorine-based disinfectants treatment. The reasons for the lower inactivation efficiency of aggregated spores are as following: the protection of outer layer spores and signals between aggregates lead to the increase of resistance for aggregated spores. This study is meaningful for the control of the fungal spores at different states in water.

Serra da Estrela PDO Cheese Microbiome as Revealed by Next Generation Sequencing

Serra da Estrela PDO cheese is the oldest traditional cheese manufactured in Portugal. In this work, its microbiome as well as the main raw materials used in cheese production, raw ewes’ milk and thistle flowers (Cynara cardunculus L.), were characterized using next generation sequencing. Samples were accordingly retrieved from a local producer over two consecutive production campaigns and at different time periods within each campaign. The bacterial and fungi communities associated with each matrix were accessed through sequencing of V3–V4 and Internal Transcribed Spacer 2 regions of rRNA gene amplicons, respectively. A high microbial diversity was found associated to each matrix, differing significantly (p < 0.05) from each other. Over 500 taxa were identified in each analyzed matrix, ranging from dominant (relative abundance > 1%), sub-dominant (0.01–1%) and rare taxa (<0.01%). Specifically, in cheese, 30 taxa were present in all analyzed samples (core taxa), including species of Leuconostoc spp. and Lactococcus spp. for bacteria and Candida spp., Debaryomyces spp. and Yarrowia spp. for fungi, that were cumulatively the most prevalent genera in Serra da Estrela PDO cheese (average relative abundance ≥10%). Ultimately, this characterization study may contribute to a better understanding of the microbial dynamics of this traditional PDO product, namely the influence of raw materials on cheese microbiome, and could assist producers interested in preserving the identity, quality and safety of Serra da Estrela PDO cheese.

Rabbit Fungal Keratitis Model of Fusarium solani Tested Against Three Commercially Available Antifungal Drugs

The purpose of this study was to develop a reproducible preclinical Fusarium solani keratitis model, which would allow comparative testing of currently available antifungals (NATACYN [Alcon, Fort Worth, TX], voriconazole 1%, and amphotericin B 0.1%) as well as efficacy testing of new antifungals for translation into clinical practice in the future.

Pharmacological Potential of Fungal Endophytes Associated with Medicinal Plants: A Review

Endophytic microbes are microorganisms that colonize the intracellular spaces within the plant tissues without exerting any adverse or pathological effects. Currently, the world population is facing devastating chronic diseases that affect humans. The resistance of pathogens to commercial antibiotics is increasing, thus limiting the therapeutic potential and effectiveness of antibiotics. Consequently, the need to search for novel, affordable and nontoxic natural bioactive compounds from endophytic fungi in developing new drugs with multifunction mechanisms to meet human needs is essential. Fungal endophytes produce invaluable bioactive metabolic compounds beneficial to humans with antimicrobial, anticancer, antidiabetic, anti-inflammatory, antitumor properties, etc. Some of these bioactive compounds include pestacin, taxol, camptothecin, ergoflavin, podophyllotoxin, benzopyran, isopestacin, phloroglucinol, tetrahydroxy-1-methylxanthone, salidroside, borneol, dibenzofurane, methyl peniphenone, lipopeptide, peniphenone etc. Despite the aforementioned importance of endophytic fungal metabolites, less information is available on their exploration and pharmacological importance. Therefore, in this review, we shall elucidate the fungal bioactive metabolites from medicinal plants and their pharmacological potential.

An Overview of Genomics, Phylogenomics and Proteomics Approaches in Ascomycota

Fungi are among the most successful eukaryotes on Earth: they have evolved strategies to survive in the most diverse environments and stressful conditions and have been selected and exploited for multiple aims by humans. The characteristic features intrinsic of Fungi have required evolutionary changes and adaptations at deep molecular levels. Omics approaches, nowadays including genomics, metagenomics, phylogenomics, transcriptomics, metabolomics, and proteomics have enormously advanced the way to understand fungal diversity at diverse taxonomic levels, under changeable conditions and in still under-investigated environments. These approaches can be applied both on environmental communities and on individual organisms, either in nature or in axenic culture and have led the traditional morphology-based fungal systematic to increasingly implement molecular-based approaches. The advent of next-generation sequencing technologies was key to boost advances in fungal genomics and proteomics research. Much effort has also been directed towards the development of methodologies for optimal genomic DNA and protein extraction and separation. To date, the amount of proteomics investigations in Ascomycetes exceeds those carried out in any other fungal group. This is primarily due to the preponderance of their involvement in plant and animal diseases and multiple industrial applications, and therefore the need to understand the biological basis of the infectious process to develop mechanisms for biologic control, as well as to detect key proteins with roles in stress survival. Here we chose to present an overview as much comprehensive as possible of the major advances, mainly of the past decade, in the fields of genomics (including phylogenomics) and proteomics of Ascomycota, focusing particularly on those reporting on opportunistic pathogenic, extremophilic, polyextremotolerant and lichenized fungi. We also present a review of the mostly used genome sequencing technologies and methods for DNA sequence and protein analyses applied so far for fungi.

The establishment of a fungal consortium in a new winery

The biodiversity and evolution of fungal communities were monitored over a period of 3 vintages in a new winery. Samples were collected before grape receipt and 3 months after fermentation from 3 different wine related environments (WRE): floor, walls and equipment and analyzed using Illumina Mi-Seq. Genera of mold and filamentous fungi (294), non-enological (10) and wine-associated yeasts (25) were detected on all WREs before the arrival of the first harvest. Among them, genera like Alternaria and Aureobasidium persisted during two vintages. Therefore, these genera are not specific to winery environment and appear to be adapted to natural or anthropic environments due to their ubiquitous character. Some genera like Candida were also detected before the first harvest but only on one WREs, whereas, on the other WREs they were found after the harvest. The ubiquitous character and phenotypic traits of these fungal genera can explain their dynamics. After the first harvest and during 3 vintages the initial consortium was enriched by oenological genera like Starmerella introduced either by harvest or by potential transfers between the different WREs. However, these establishing genera, including Saccharomyces, do not appear to persist due to their low adaptation to the stressful conditions of winery environment.

Nidulantes of Aspergillus (Formerly Emericella): A Treasure Trove of Chemical Diversity and Biological Activities

The genus Emericella (Ascomycota) includes more than thirty species with worldwide distribution across many ecosystems. It is considered a rich source of diverse metabolites. The published classes of natural compounds that are discussed here are organized according to the following biosynthetic pathways: polyketides (azaphilones, cyclopentenone pigments, dicyanides, furan derivatives, phenolic ethers, and xanthones and anthraquinones); shikimate derivatives (bicoumarins); mevalonate derivatives (meroterpenes, sesquiterpenes, sesterterpenes and steroids) and amino acids derivatives (alkaloids (indole-derivatives, isoindolones, and piperazine) and peptides (depsipeptides)). These metabolites produce the wide array of biological effects associated with Emericella, including antioxidant, antiproliferative, antimalarial, antiviral, antibacterial, antioxidant, antihypertensive, anti-inflammatory, antifungal and kinase inhibitors. Careful and extensive study of the diversity and distribution of metabolites produced by the genus Emericella (either marine or terrestrial) revealed that, no matter the source of the fungus, the composition of the culture medium effectively controls the metabolites produced. The topic of this review is the diversity of metabolites that have been identified from Emericella, along with the contextual information on either their biological or geographic sources. This review presents 236 natural compounds, which were reported from marine and terrestrial Emericella. Amongst the reported compounds, only 70.2% were biologically assayed for their effects, including antimicrobial or cytotoxicity. This implies the need for substantial investigation of alternative activities. This review includes a full discussion of compound structures and disease management, based on materials published from 1982 through December 2019.

The Composition and Phosphorus Cycling Potential of Bacterial Communities Associated With Hyphae of Penicillium in Soil Are Strongly Affected by Soil Origin

Intimate fungal-bacterial interactions are widespread in nature. However the main drivers for the selection of hyphae-associated bacterial communities and their functional traits in soil systems remain elusive. In the present study, baiting microcosms were used to recover hyphae-associated bacteria from two Penicillium species with different phosphorus-solubilizing capacities in five types of soils. Based on amplicon sequencing of 16S rRNA genes, the composition of bacterial communities associated with Penicillium hyphae differed significantly from the soil communities, showing a lower diversity and less variation in taxonomic structure. Furthermore, soil origin had a significant effect on hyphae-associated community composition, whereas the two fungal species used in this study had no significant overall impact on bacterial community structure, despite their different capacities to solubilize phosphorus. However, discriminative taxa and specific OTUs were enriched in hyphae-associated communities of individual Penicillium species indicating that each hyphosphere represented a unique niche for bacterial colonization. Additionally, an increased potential of phosphorus cycling was found in hyphae-associated communities, especially for the gene phnK involved in phosphonate degradation. Altogether, it was established that the two Penicillium hyphae represent unique niches in which microbiome assemblage and phosphorus cycling potential are mainly driven by soil origin, with less impact made by fungal identity with a divergent capacity to utilize phosphorus.