Could the transcription factor AtnN coordinating the aspercryptin secondary metabolite gene cluster in Aspergillus nidulans be a global regulator?

Products of dormant secondary metabolite gene clusters of fungal genomes can be exploited for medical purposes as bioactive agents. These clusters can be switched on under oxidative stress and may endow fungi with a versatile chemical armory in a competitive niche. In Aspergillus nidulans, the aspercryptin gene cluster, including the synthase [atnA (AN7884)] and its transcription factor (atnN), was activated under menadione sodium bisulfite (MSB) treatment.

Biotechnological potential of salt tolerant and xerophilic species of Aspergillus.

Xerophilic fungi occupy versatile environments owing to their rich arsenal helping them successfully adapt to water constraints as a result of low relative humidity, high-osmolarity, and high-salinity conditions. The general term xerophilic fungi relates to organisms that tolerate and/or require reduced water activity, while halophilic and osmophilic are applied to specialized groups that require high salt concentrations or increased osmotic pressure, respectively. Species belonging to the family Aspergillaceae, and especially those classified in Aspergillus subgenus Aspergillus (sections Restricti and Aspergillus) and Polypaecilum, are particularly enriched in the group of osmophilic and salt-tolerant filamentous fungi.

The bacterial and yeast microbiota in livestock forages in Hungary.

Background: Along bacteria, yeasts are common in forages and forage fermentations as spoilage microbes or as additives, yet few studies exist with species-level data on these fungi's occurrence in feedstuff. Active dry yeast and other yeast-based products are also common feed additives in animal husbandry. Here, we aimed to characterize both fermented and non-fermented milking cow feedstuff samples from Hungary to assess their microbial diversity in the first such study from Central Europe.

, Encoding the Hyperosmotic Stress Protein Glycerol-3-phosphate Dehydrogenase, Disrupts Osmoadaptation in .

The genome of the osmophilic , unlike that of the osmotolerant , contains only the , but not the , glycerol 3-phosphate dehydrogenase gene. Here, we studied transcriptomic changes of (reference strain and Δ gene deletion mutant) and (reference strain and expressing mutant) elicited by high osmolarity. showed a canonic hyperosmotic stress response characterized by the upregulation of the trehalose and glycerol metabolism genes (including ), as well as the genes of the high-osmolarity glycerol (HOG) map kinase pathway.

Total transcriptome response for tyrosol exposure in Aspergillus nidulans.

Although tyrosol is a quorum-sensing molecule of Candida species, it has antifungal activity at supraphysiological concentrations. Here, we studied the effect of tyrosol on the physiology and genome-wide transcription of Aspergillus nidulans to gain insight into the background of the antifungal activity of this compound. Tyrosol efficiently reduced germination of conidia and the growth on various carbon sources at a concentration of 35 mM.

The Oxidative Stress Response Highly Depends on Glucose and Iron Availability in .

Pathogens have to cope with oxidative, iron- and carbon(glucose)-limitation stresses in the human body. To understand how combined iron-carbon limitation alters oxidative stress responses, was cultured in glucose-peptone or peptone containing media supplemented or not with deferiprone as an iron chelator. Changes in the transcriptome in these cultures were recorded after HO treatment.

Global Transcriptomic Changes Elicited by Deletion and Menadione Exposure in .

Manganese superoxide dismutases (MnSODs) play a pivotal role in the preservation of mitochondrial integrity and function in fungi under various endogenous and exogenous stresses. Deletion of mnSOD/SodB increased oxidative stress sensitivity and apoptotic cell death rates as well as affected antioxidant enzyme and sterigmatocystin productions, respiration, conidiation and the stress tolerance of conidiospores. The physiological consequences of the lack of were more pronounced during carbon starvation than in the presence of glucose.

The bZIP-type transcription factors NapA and RsmA modulate the volumetric ratio and the relative superoxide ratio of mitochondria in Aspergillus nidulans.

Basic leucine zipper (bZIP) transcription factors are crucial components of differentiation, cellular homeostasis and the environmental stress defense of eukaryotes. In this work, we further studied the consequence of gene deletion and overexpression of two bZIP transcription factors, NapA and RsmA, on superoxide production, mitochondrial morphology and hyphal diameter of Aspergillus nidulans. We have found that reactive oxygen species production was influenced by both gene deletion and overexpression of napA under tert-butylhydroperoxide (tBOOH) elicited oxidative stress.

Functional characterization of genes encoding cadmium pumping P-type ATPases in and .

Several P-type ATPases are important Cd/Cu pumps in species, and they are tightly associated with the heavy metal stress tolerance of these ascomycetous fungi. To better understand the roles of the two P-type ATPases, CrpA Cd/Cu pump (orthologue of the Cd/Cu pump) and PcaA Cd pump (orthologue of the Pca1 Cd pump), we have generated individual mutants and characterized their heavy metal susceptibilities. The deletion of CrpA in has led to the increased sensitivity of the fungus to stresses induced by Zn, Fe, or the combination of oxidative-stress-inducing menadione sodium bisulfite and Fe.

pH-dependent effect of Congo Red on the growth of Aspergillus nidulans and Aspergillus niger.

The azo dye Congo Red (CR) is frequently used as an agent to elicit cell wall integrity stress in fungi. This highly toxic aromatic, heterocyclic compound contains two azo bonds as chromophore, which are responsible for protonation under acidic conditions, leading to changes in the molecular structure of the dye and the color of the solution. The investigation of how CR affects the growth of Aspergillus nidulans and Aspergillus niger on surface cultures provided us with evidence about its pH-dependent toxicity.

New perspectives in application of kidney biomarkers in mycotoxin induced nephrotoxicity, with a particular focus on domestic pigs.

The gradual spread of worldwide is adding to the global shortage of food and is affecting its safe consumption. -derived mycotoxins, including aflatoxins and ochratoxin A, and fumonisins (members of the fusariotoxin group) can cause pathological damage to vital organs, including the kidney or liver. Although the kidney functions as the major excretory system in mammals, monitoring and screening for mycotoxin induced nephrotoxicity is only now a developmental area in the field of livestock feed toxicology.

The Effect of Environmental Factors on Mould Counts and AFB1 Toxin Production by in Maize.

The toxins produced by can significantly inhibit the use of maize. As a result of climate change, toxin production is a problem not only in tropical and subtropical areas but in an increasing number of European countries, including Hungary. The effect of meteorological factors and irrigation on mould colonization and aflatoxin B1 (AFB1) mycotoxin production by were investigated in natural conditions, as well as the inoculation with a toxigenic isolate in a complex field experiment for three years.

Species-specific effects of the introduction of Aspergillus nidulans gfdB in osmophilic aspergilli.

Industrial fungi need a strong environmental stress tolerance to ensure acceptable efficiency and yields. Previous studies shed light on the important role that Aspergillus nidulans gfdB, putatively encoding a NAD-dependent glycerol-3-phosphate dehydrogenase, plays in the oxidative and cell wall integrity stress tolerance of this filamentous fungus model organism. The insertion of A.

Genome-Wide Gene Expression Analyses of the AtfA/AtfB-Mediated Menadione Stress Response in .

The bZIP transcription factors (TFs) govern regulation of development, secondary metabolism, and various stress responses in filamentous fungi. In this work, we carried out genome-wide expression studies employing Illumina RNAseq to understand the roles of the two bZIP transcription factors AtfA and AtfB in . Comparative analyses of transcriptomes of control, Δ, Δ, and ΔΔ mutant strains were performed.

Advanced mycotoxin control and decontamination techniques in view of an increased aflatoxin risk in Europe due to climate change.

Aflatoxins are toxic secondary metabolites produced by spp. found in staple food and feed commodities worldwide. Aflatoxins are carcinogenic, teratogenic, and mutagenic, and pose a serious threat to the health of both humans and animals.

Stress Responses Elicited by Glucose Withdrawal in .

Glucose is a widely used carbon source in laboratory practice to culture Aspergillus fumigatus, however, glucose availability is often low in its “natural habitats”, including the human body. We used a physiological−transcriptomical approach to reveal differences between A. fumigatus Af293 cultures incubated on glucose, glucose and peptone, peptone (carbon limitation), or without any carbon source (carbon starvation).

Whole blood transcriptome characterization of young female triathlon athletes following an endurance exercise: a pilot study.

The vast majority of studies focusing on the effects of endurance exercise on hematological parameters and leukocyte gene expression were performed in adult men, so our aim was to investigate these changes in young females. Four young (age 15.3 ± 1.

Optimization and Validation of ELISA for Aflatoxin B1 Detection in Fermented Forages and Feeds.

Enzyme-coupled immunosorbent assays (ELISA) methods are usually validated only for homogenous matrixes like corn and wheat. More complex materials like fermented forages and mixed feed are not targeted for mycotoxin measurement. The low number of ELISA methods found in the literature neither contained the pH set for fermented forages nor dealt with the setting of the matrix:solvent ratio.

Functional analysis of the bZIP-type transcription factors AtfA and AtfB in .

Transcription factors (TFs) with the basic leucin zipper domain are key elements of the stress response pathways in filamentous fungi. In this study, we functionally characterized the two bZIP type TFs AtfA and AtfB by deletion () and overexpression (OE) of their encoding genes in all combination: OE, OE, OE, OE and OEOE in . Based on our previous studies, increased the sensitivity of the fungus to oxidative stress mediated by menadione sodium bisulfite (MSB) and tert-butylhydroperoxide (BOOH), while was not sensitive to any oxidative stress generating agents, namely MSB, BOOH and diamide at all.

Elimination of Deoxynivalenol, Aflatoxin B1, and Zearalenone by Gram-Positive Microbes ().

Mycotoxin contaminations in the feed and food chain are common. Either directly or indirectly, mycotoxins enter the human body through the consumption of food of plant and animal origin. Bacteria with a high mycotoxin elimination capability can reduce mycotoxin contamination in feed and food.

Probabilistic modeling and risk characterization of the chronic aflatoxin M1 exposure of Hungarian consumers.

Aflatoxin contamination can appear in various points of the food chain. If animals are fed with contaminated feed, AFB1 is transformed-among others-to aflatoxin M1 (AFM1) metabolite. AFM1 is less toxic than AFB1, but it is still genotoxic and carcinogenic and it is present in raw and processed milk and all kinds of milk products.

Effect of the combinatorial iron-chelation and oxidative stress on the growth of Aspergillus species.

The growth of 14 Aspergillus strains belonging to nine species was studied under combinatorial deferriprone - HO (iron-chelation - oxidative) stress. When deferriprone pretreated mycelia were subjected to even a weak oxidative stress, the growth inhibitory effect of iron-chelation stress was enhanced in 10 out of 14 strains. In contrast, oxidative stress pretreatment of conidia increased their deferriprone tolerance in 10 strains.