Mycotoxin Accumulation in Dry Rot Potato Tubers from Algeria and Toxigenic Potential of Associated Isolates of Fusarium Genus.

The presence of different mycotoxins in 232 tuber samples exhibiting dry rot symptoms and their associated Fusarium strains from two production sites in Algeria was investigated. LC-MS/MS was used to simultaneously detect and quantify 14 mycotoxins, including trichothecenes and non-trichothecenes. A total of 49 tubers were contaminated with at least one mycotoxins, including T-2, HT-2, Diacetoxyscirpenol (DAS), 15-acetoxyscirpenol (15-AS) and Beauvericin (BEA). Positive samples from the Bouira region had a significantly higher level of toxin contamination compared to Ain Defla (56.34% and 5.59%, respectively). A total of 283 Fusarium strains were isolated: 155 from Bouira and 128 from Ain Defla. These strains were evaluated for their ability to produce the targeted mycotoxins. The results showed that 61.29% and 53.9% of strains originate from Bouira and Ain Defla regions were able to produce Nivalenol, Fusarenone-X, DAS, 15-AS, Neosolaniol, BEA and Zearalenone. The phylogenetic analysis of the conserved ribosomal internal transcribed spacer (ITS) sequences of 29 Fusarium strains, representative of the recorded mycotoxins profiles, was distributed into 5 Fusarium species complexes (SC): F. incarnatum-equiseti SC (FIESC), F. sambucinum SC (FSAMSC), F. oxysporum SC (FOSC), F. tricinctum SC (FTSC) and F. redolens SC (FRSC). This is the first study determining multiple occurrences of mycotoxins contamination associated to Fusarium dry rot of potato in Algeria and highlights fungal potential for producing trichothecene and non-trichothecens mycotoxins.

Antifungal metabolites produced by Pseudomonas hunanensis SPT26 effective in biocontrol of fusarium wilt of Lycopersicum esculentum under saline conditions.

In past few years, salinity has become one of the important abiotic stresses in the agricultural fields due to anthropogenic activities. Salinity is leading towards yield losses due to soil infertility and increasing vulnerability of crops to diseases. Fluorescent pseudomonads are a diverse group of soil microorganisms known for promoting plant growth by involving various traits including protecting crops from infection by the phytopathogens. In this investigation, salt tolerant plant growth promoting bacterium Pseudomonas hunanensis SPT26 was selected as an antagonist against Fusarium oxysporum, causal organism of fusarium wilt in tomato. P. hunanensis SPT26 was found capable to produce various antifungal metabolites. Characterization of purified metabolites using Fourier transform infrared spectroscopy (FT-IR) and liquid chromatography-electron spray ionization-mass spectrometry (LC-ESI/MS) showed the production of various antifungal compounds viz., pyrolnitrin, pyochelin and hyroxyphenazine by P. hunanensis SPT26. In the preliminary examination, biocontrol activity of purified antifungal metabolites was checked by dual culture method and results showed 68%, 52% and 65% growth inhibition by pyrolnitrin, 1- hydroxyphenazine and the bacterium (P. hunanensis SPT26) respectively. Images from scanning electron microscopy (SEM) revealed the damage to the mycelia of fungal phytopathogen due to production of antifungal compounds secreted by P. hunanensis SPT26. Application of bioinoculant of P. hunanensis SPT26 and purified metabolites significantly decreased the disease incidence in tomato and increased the plant growth parameters (root and shoot length, antioxidant activity, number of fruits per plant, etc.) under saline conditions. The study reports a novel bioinoculant formulation with the ability to promote plant growth parameters in tomato in presence of phytopathogens even under saline conditions.

A cyclic lipopeptide from Fusarium graminearum targets plant membranes to promote virulence.

Microbial plant pathogens deploy amphipathic cyclic lipopeptides to reduce surface tension in their environment. While plants can detect these molecules to activate cellular stress responses, the role of these lipopeptides or associated host responses in pathogenesis are not fully clear. The gramillin cyclic lipopeptide is produced by the Fusarium graminearum fungus and is a virulence factor and toxin in maize. Here, we show that gramillin promotes virulence and necrosis in both monocots and dicots by disrupting ion balance across membranes. Gramillin is a cation-conducting ionophore and causes plasma membrane depolarization. This disruption triggers cellular signaling, including a burst of reactive oxygen species (ROS), transcriptional reprogramming, and callose production. Gramillin-induced ROS depends on expression of host ILK1 and RBOHD genes, which promote fungal induction of virulence genes during infection and host susceptibility. We conclude that gramillin's ionophore activity targets plant membranes to coordinate attack by the F. graminearum fungus.

[Construction of ATMT system of Fusarium oxysporum and evaluation of its promoting effect on Glycyrrhiza uralensis].

This study aims to evaluate the in vivo function of Fusarium oxysporum in Glycyrrhiza uralensis by salt tolerance,indoleacetic acid(IAA) production capacity, phosphate-dissolving capacity, and iron carrier production capacity. The stable genetic transformation system of the F. oxysporum was established by Agrobacterium tumefaciens-mediated genetic transformation( ATMT)technology, and the stability and staining efficiency of transformants were detected by the cloning of the marker gene green fluorescent protein(GFP) and the efficiency of ß-glucuronidase staining(GUS). Efficient and stable transformants were selected for restaining G. uralensis and evaluating its influence on the growth of the G. uralensis seedlings. The results show that F. oxysporum has good salt tolerance and could still grow on potato glucose agar(PDA) medium containing 7% sodium chloride, but the growth rate slows down with the increase in sodium chloride content in PDA medium. F. oxysporum has the function of producing indoleacetic acid, and the concentration of IAA in its fermentation broth is about 3. 32 mg · m L~(-1). In this study, the genetic transformation system of F. oxysporum is successfully constructed, and the ATMT system is efficient and stable. One transformant with both high staining efficiency and genetic stability is selected, and the restaining rate of the transformant in G. uralensis is 76. 92%, which could significantly improve the main root length of one-month-old G. uralensis seedlings and promote the growth and development of G. uralensis seedlings. The results of this study can lay the foundation for the development of biological bacterial fertilizer and the growth regulation of high-quality G. uralensis.

Streptomyces-Secreted Fluvirucin B6 as a Potential Bio-Fungicide for Managing Banana Fusarium Wilt and Mycotoxins and Modulating the Soil Microbial Community Structure.

Banana Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc TR4) is the most destructive soil-borne fungal disease. Until now, there has been a lack of effective measures to control the disease. It is urgent to explore biocontrol agents to control Foc TR4 and the secretion of mycotoxin. In this study, fluvirucin B6 was screened from Streptomyces solisilvae using an activity-guided method. Fluvirucin B6 exhibited strong antifungal activity against Foc TR4 (0.084 mM of EC50 value) and significantly inhibited mycelial growth and spore germination. Further studies demonstrated that fluvirucin B6 could cause the functional loss of mitochondria, the disorder of metabolism of Foc TR4 cells, and the decrease of enzyme activities in the tricarboxylic acid cycle and electron transport chain, ultimately inhibiting mycotoxin metabolism. In a pot experiment, the application of fluvirucin B6 significantly decreased the incidence of banana Fusarium wilt and the amount of Foc TR4 and controlled fungal toxins in the soil. Additionally, fluvirucin B6 could positively regulate the changes in the structure of the banana rhizosphere microbial community, significantly enriching beneficial microbes associated with disease resistance. In summary, this study identifies fluvirucin B6, which plays versatile roles in managing fungal diseases and mycotoxins.

Enhancing bacterial biodegradation of n-hexane by utilizing the adsorption capacity of non-degrading fungi.

Biodegradation of hydrophobic volatile organic compounds (VOCs) such as n-hexane is limited by their poor accessibility. Constructing fungal-bacterial degradation alliances is an effective approach, but the role of those fungi without the capability to degrade VOCs may have been overlooked. In this study, a non-n-hexane-degrading fungus, Fusarium keratoplasticum FK, was utilized to enhance n-hexane degradation by the bacterium Mycobacterium neworleansense WCJ. It was shown that strain WCJ removed 64.84% of n-hexane (at a concentration of 648.20 mg L-1) over 3 d, and 84.04% after introducing strain FK. Microbial growth kinetic studies revealed that the growth of strain WCJ was also promoted. Through a stepwise adsorption-degradation experiment combined with qPCR technology, it was found that the strain WCJ could utilize the n-hexane pre-adsorbed by strain FK, with an increase in copy number from 108.2662 to 108.7731. Therefore, the non-degrading fungi can improved the accessibility of n-hexane by providing n-hexane adsorbed by the mycelium to the degrading bacteria. In addition, the adsorption tests and characterization of the fungal samples before and after Soxhlet extraction indicated that the adsorption of n-hexane on strain FK conformed to Lagergren's pseudo-second-order kinetics and Freundlich adsorption isotherms, and was correlated with the presence of lipids and nonpolar groups. This study emphasizes the potential role of non-degrading fungi in bioremediation and proposes a viable strategy to enhance the bacterial degradation of hydrophobic VOCs.

Transcriptional dynamics of Fusarium pseudograminearum under high fungicide stress and the important role of FpZRA1 in fungal pathogenicity and DON toxin production.

Fusarium pseudograminearum, the causal agent of Fusarium crown rot, poses a significant threat to cereal crops. Building upon our previous investigation of the transcriptional response of this pathogen to four key fungicides (carbendazim, phenamacril, pyraclostrobin, and tebuconazole), this study delves into the impact of elevated fungicide concentrations using RNA-seq. Global transcriptomic analysis and gene clustering revealed significant enrichment of genes involved in the ABC transporter pathway. Among these transporters, FPSE_06011 (FpZRA1), a conserved gene in eukaryotes, exhibited consistent upregulation at both low and high fungicide concentrations. Targeted deletion of FpZRA1 resulted in reduced sporulation, spore germination, and tolerance to cell wall stress, osmotic stress, and oxidative stress. Furthermore, the FpZRA1 knockout mutants exhibited decreased pathogenicity on wheat coleoptiles and reduced production of the mycotoxin deoxynivalenol (DON), as evidenced by the markedly down-regulated expression of TRI5, TRI6, and TRI10 in the RT-qPCR analysis. In summary, our findings highlight the impact of fungicide concentration on transcriptional reprogramming in F. pseudograminearum and identify FpZRA1 as a critical regulator of fungal development, stress tolerance, and pathogenicity.

Unveiling the Mechanism of Phenamacril Resistance in F. graminearum: Computational and Experimental Insights into the C423A Mutation in FgMyoI.

Phenamacril (PHA) is a highly selective fungicide for controlling fusarium head blight (FHB) mainly caused by F. graminearum and F. asiaticum. However, the C423A mutation in myosin I of F. graminearum (FgMyoI) leads to natural resistance to PHA. Here, based on the computational approaches and biochemical validation, we elucidate the atomic-level mechanism behind the natural resistance of F. graminearum to the fungicide PHA due to the C423A mutation in FgMyoI. The mutation leads to a rearrangement of pocket residues, resulting in increased size and flexibility of the binding pocket, which impairs the stable binding of PHA. MST experiments confirm that the mutant protein FgMyoIC423A exhibits significantly reduced affinity for PHA compared to wild-type FgMyoI and the nonresistant C423K mutant. This decreased binding affinity likely underlies the development of PHA resistance in F. graminearum. Conversely, the nonresistant C423K mutant retains sensitivity to PHA due to the introduction of a strong hydrogen bond donor, which facilitates stable binding of PHA in the pocket. These findings shed light on the molecular basis of PHA resistance and provide new directions for the creation of new myosin inhibitors.

Co-occurrence of mycotoxins in stored maize from southern and southwestern Ethiopia.

Maize grain samples collected from 129 small-scale farmers' stores in southern and southwestern Ethiopia were analysed by LC-MS/MS for a total of 218 mycotoxins and other fungal metabolites of which 15% were regulated mycotoxins. Mycotoxins produced by Penicillium, Aspergillus, and Fusarium accounted for 31%, 17%, and 12% of the metabolites, respectively. Most of the current samples were contaminated by masked and/or emerging mycotoxins with moniliformin being the most prevalent one, contaminating 93% of the samples. Each sample was co-contaminated by 3 to 114 mycotoxins/fungal metabolites. Zearalenone, fumonisin B1, and deoxynivalenol were the dominant mycotoxins, occurring in 78%, 61%, and 55% of the samples with mean concentrations of 243, 429, and 530 µg/kg, respectively. The widespread co-occurrence of several mycotoxins in the samples may pose serious health risks due to synergistic/additional effects.

Study on the inhibitory mechanism of fig leaf extract against postharvest Fusarium in melon.

The objective of this study was to explore the fungistatic mechanism of fig leaf extract against Fusarium and to provide a theoretical basis for the development of new plant-derived fungicides. Methods: The fungistaticity of fig leaf extract were analyzed by the ring of inhibition method. Fusarium equiseti was selected as the target for analyzing its fungistatic mechanism in terms of mycelial morphology, ultrastructure, cell membrane permeability, membrane plasma peroxidation, reactive oxygen species (ROS) content and changes in the activity of protective enzymes. The effect of this extract was verified in melon, and its components were determined by metabolite analysis using ultraperformance liquid chromatography‒mass spectrometry (UPLC‒MS). Results: Fig leaf extract had an obvious inhibitory effect on Fusarium, and the difference was significant (P < 0.05) or highly significant (P < 0.01). Scanning and transmission electron microscopy revealed that F. equiseti hyphae exhibited obvious folding, twisting and puckering phenomena, resulting in an increase in the cytoplasmic leakage of spores, interstitial plasma, and the concentration of the nucleus, which seriously damaged the integrity of the fungal cell membrane. This phenomenon was confirmed by propidium iodide (PI) and fluorescein diacetate (FAD) staining, cell membrane permeability and malondialdehyde (MDA) content. Fig leaf extract also induced the mycelium to produce excessive H2O2,which led to lipid peroxidation of the cell membrane, promoted the accumulation of MDA, accelerated protein hydrolysis, induced an increase in antioxidant enzyme activity, and disrupted the balance of ROS metabolism; these findings showed that fungal growth was inhibited, which was verified in melons. A total of 1,540 secondary metabolites were detected by broad-targeted metabolomics, among which the fungistatic active substances flavonoids (15.45%), phenolic acids (15%), and alkaloids (10.71%) accounted for a high percentage and the highest relative content of these substances 1,3,7,8-tetrahydroxy-2- prenylxanthone, 8-hydroxyquinoline and Azelaic acid were analysed for their antimicrobial, anti-inflammatory, antioxidant, preventive effects against plant diseases and acquisition of resistance by plants. This confirms the reason for the fungicidal properties of fig leaf extracts. Conclusion: Fig leaf extract has the potential to be developed into a plant-derived fungicide as a new means of postharvest pathogen prevention and control in melon.

First Report on Mycotoxin Contamination of Hops (Humulus lupulus L.).

The presence of mycotoxins and other toxic metabolites in hops (Humulus lupulus L.) was assessed for the first time. In total, 62 hop samples were sampled in craft breweries, and analyzed by a multi-toxin LS-MS/MS method. The study collected samples from craft breweries in all of the Croatian counties and statistically compared the results. Based on previous reports on Alternaria spp. and Fusarium spp. contamination of hops, the study confirmed the contamination of hops with these toxins. Alternaria toxins, particularly tenuazonic acid, were found in all tested samples, while Fusarium toxins, including deoxynivalenol, were present in 98% of samples. However, no Aspergillus or Penicillium metabolites were detected, indicating proper storage conditions. In addition to the Alternaria and Fusarium toxins, abscisic acid, a drought stress indicator in hops, was also detected, as well as several unspecific metabolites. The findings suggest the need for monitoring, risk assessment, and potential regulation of Alternaria and Fusarium toxins in hops to ensure the safety of hop usage in the brewing and pharmaceutical industries. Also, four local wild varieties were tested, with similar results to the commercial varieties for toxin contamination, but the statistically significant regional differences in toxin occurrence highlight the importance and need for targeted monitoring.

Increased Dissemination of Aflatoxin- and Zearalenone-Producing Aspergillus spp. and Fusarium spp. during Wet Season via Houseflies on Dairy Farms in Aguascalientes, Mexico.

Crops contamination with aflatoxins (AFs) and zearalenone (ZEA) threaten human and animal health; these mycotoxins are produced by several species of Aspergillus and Fusarium. The objective was to evaluate under field conditions the influence of the wet season on the dissemination of AF- and ZEA-producing fungi via houseflies collected from dairy farms. Ten dairy farms distributed in the semi-arid Central Mexican Plateau were selected. Flies were collected in wet and dry seasons at seven points on each farm using entomological traps. Fungi were isolated from fly carcasses via direct seeding with serial dilutions and wet chamber methods. The production of AFs and ZEA from pure isolates was quantified using indirect competitive ELISA. A total of 693 Aspergillus spp. and 1274 Fusarium spp. isolates were obtained, of which 58.6% produced AFs and 50.0% produced ZEA (491 ± 122; 2521 ± 1295 µg/kg). Houseflies and both fungal genera were invariably present, but compared to the dry season, there was a higher abundance of flies as well as AF- and ZEA-producing fungi in the wet season (p < 0.001; 45.3/231 flies/trap; 8.6/29.6% contaminated flies). These results suggest that rainy-weather conditions on dairy farms increase the spread of AF- and ZEA-producing Aspergillus spp. and Fusarium spp. through houseflies and the incorporation of their mycotoxins into the food chain.

Optimizing microbial strain selection for pyrethroid biodegradation in contaminated environments through a TOPSIS-based decision-making system.

Improved and contemporary agriculture relies heavily on pesticides, yet some can be quite persistent and have a stable chemical composition, posing a significant threat to the ecology. Removing harmful effects is upon their degradability. Biodegradation must be emphasized to lower pesticide degradation costs, especially in the soil. Here, a decision-making system was used to determine the best microbial strain for the biodegradation of the pyrethroid-contaminated soil. In this system, the criteria chosen as: pH (C1), Temp (C2), RPM (C3), Conc. (C4), Degradation (%) (C5) and Time required for degradation(hrs) (C6); and five alternatives were Bacillus (A1), Acinetobacter (A2), Escherichia (A3), Pseudomonas (A4), and Fusarium (A5). The best alternative was selected by applying the TOPSIS (technique for order performance by similarity to ideal solution) method, which evaluates based on their closeness to the ideal solution and how well they meet specific requirements. Among all the specified criteria, Acinetobacter (A2) was the best and optimal based on the relative closeness value (( R i ∗ ) = 0.740 (A2) > 0.544 (A5) > 0.480 (A1) > 0.403 (A4) > 0.296 (A3)). However, the ranking of the other alternatives is also obtained in the order Fusarium (A5), Bacillus (A1), Pseudomonas (A4), Escherichia (A3). Hence this study suggests Acinetobacter is the best microbial strain for biodegradation of pyrethroids; while least preference should be given to Escherichia. Acinetobacter, versatile metabolic nature with various xenobiotic compounds' degradation ability, is gram-negative, aerobic, coccobacilli, nonmotile, and nonspore forming bacteria. Due to less study about Acinetobacter it is not in that much frame as the other microorganisms. Hence, considering the Acinetobacter strain for the biodegradation study will give more optimal results than the other microbial strains. Novelty of this study, the TOPSIS method is applied first time in selecting the best microbial strain for the biodegradation of pyrethroid-contaminated soil, considering this selection process as multi-criteria decision-making (MCDM) problem.

Molecular Mechanism of Fusarium Fungus Inhibition by Phenazine-1-carboxamide.

Fusarium head blight caused by Fusarium graminearum is a devastating disease in wheat that seriously endangers food security and human health. Previous studies have found that the secondary metabolite phenazine-1-carboxamide produced by biocontrol bacteria inhibited F. graminearum by binding to and inhibiting the activity of histone acetyltransferase Gcn5 (FgGcn5). However, the detailed mechanism of this inhibition remains unknown. Our structural and biochemical studies revealed that phenazine-1-carboxamide (PCN) binds to the histone acetyltransferase (HAT) domain of FgGcn5 at its cosubstrate acetyl-CoA binding site, thus competitively inhibiting the histone acetylation function of the enzyme. Alanine substitution of the residues in the binding site shared by PCN and acetyl-CoA not only decreased the histone acetylation level of the enzyme but also dramatically impacted the development, mycotoxin synthesis, and virulence of the strain. Taken together, our study elucidated a competitive inhibition mechanism of Fusarium fungus by PCN and provided a structural template for designing more potent phenazine-based fungicides.

Attempting to Create a Pathway to 15-Deacetylcalonectrin with Limited Accumulation in Cultures of Fusarium Tri3 Mutants: Insight into Trichothecene Biosynthesis Machinery.

The compound 15-deacetylcalonectrin (15-deCAL) is a common pathway intermediate in the biosynthesis of Fusarium trichothecenes. This tricyclic intermediate is metabolized to calonectrin (CAL) by trichothecene 15-O-acetyltransferase encoded by Tri3. Unlike other trichothecene pathway Tri gene mutants, the Δtri3 mutant produces lower amounts of the knocked-out enzyme's substrate 15-deCAL, and instead, accumulates higher quantities of earlier bicyclic intermediate and shunt metabolites. Furthermore, evolutionary studies suggest that Tri3 may play a role in shaping the chemotypes of trichothecene-producing Fusarium strains. To better understand the functional role of Tri3p in biosynthesis and evolution, we aimed to develop a method to produce 15-deCAL by using transgenic Fusarium graminearum strains derived from a trichothecene overproducer. Unfortunately, introducing mutant Tri3, encoding a catalytically impaired but structurally intact acetylase, did not improve the low 15-deCAL production level of the ΔFgtri3 deletion strain, and the bicyclic products continued to accumulate as the major metabolites of the active-site mutant. These findings are discussed in light of the enzyme responsible for 15-deCAL production in trichothecene biosynthesis machinery. To efficiently produce 15-deCAL, we tested an alternative strategy of using a CAL-overproducing transformant. By feeding a crude CAL extract to a Fusarium commune strain that was isolated in this study and capable of specifically deacetylating C-15 acetyl, 15-deCAL was efficiently recovered. The substrate produced in this manner can be used for kinetic investigations of this enzyme and its possible role in chemotype diversification.

Validamycin A Inhibited FB1 Biosynthesis by the Target FvNth in Fusarium verticillioides.

Validamycin A (VMA) is an antifungal antibiotic derived from Streptomyces hygroscopicus commonly used in plant disease management. Surprisingly, VMA was discovered to impede the production of fumonisin B1 (FB1) in agricultural settings. However, the specific target of VMA in Fusarium verticillioides remained unclear. To unravel the molecular mechanism of VMA, ultrastructural observations unveiled damage to mitochondrial membranes. Trehalase (FvNth) was pinpointed as the target of VMA by utilizing a 3D-printed surface plasmon resonance sensor. Molecular docking identified Trp285, Arg447, Asp452, and Phe665 as the binding sites between VMA and FvNth. A ΔFvnth mutant lacking amino acids 250-670 was engineered through homologous recombination. Transcriptome analysis indicated that samples treated with VMA and ΔFvnth displayed similar expression patterns, particularly in the suppression of the FUM gene cluster. VMA treatment resulted in reduced trehalase and ATPase activity as well as diminished production of glucose, pyruvic acid, and acetyl-CoA. Conversely, these effects were absent in samples treated with ΔFvnth. This research proposes that VMA hinders acetyl-CoA synthesis by trehalase, thereby suppressing the FB1 biosynthesis. These findings present a novel target for the development of mycotoxin control agents.

The trichothecene mycotoxin deoxynivalenol facilitates cell-to-cell invasion during wheat-tissue colonization by Fusarium graminearum.

Fusarium head blight disease on small-grain cereals is primarily caused by the ascomycete fungal pathogen Fusarium graminearum. Infection of floral spike tissues is characterized by the biosynthesis and secretion of potent trichothecene mycotoxins, of which deoxynivalenol (DON) is widely reported due to its negative impacts on grain quality and consumer safety. The TRI5 gene encodes an essential enzyme in the DON biosynthesis pathway and the single gene deletion mutant, ΔTri5, is widely reported to restrict disease progression to the inoculated spikelet. In this study, we present novel bioimaging evidence revealing that DON facilitates the traversal of the cell wall through plasmodesmata, a process essential for successful colonization of host tissue. Chemical complementation of ΔTri5 did not restore macro- or microscopic phenotypes, indicating that DON secretion is tightly regulated both spatially and temporally. A comparative qualitative and quantitative morphological cellular analysis revealed infections had no impact on plant cell wall thickness. Immunolabelling of callose at plasmodesmata during infection indicates that DON can increase deposits when applied exogenously but is reduced when F. graminearum hyphae are present. This study highlights the complexity of the interconnected roles of mycotoxin production, cell wall architecture and plasmodesmata in this highly specialized interaction.

Preparation of porous biochar from fusarium wilt-infected banana straw for remediation of cadmium pollution in water bodies.

The problem of cadmium pollution and its control is becoming increasingly severe issue in the world. Banana straw is an abundant bio raw material, but its burning or discarding in field not only causes pollution but also spreads fusarium wilt. The objective of this paper is to utilize biochar derived from the wilt-infected banana straw for remediation of Cd(II) pollution while to eliminate the pathogen. The activity of wilt pathogen in biochar was determined by PDA petri dish test. The Cd(II) adsorption of the biochar was determined by batch adsorption experiments. The effects of KOH concentration (0.25, 0.5 and 0.75 M) on the physicochemical characteristics of the biochar were also observed by BET, SEM, FTIR, XRD and XPS. Results showed that pristine banana straw biochar (PBBC) did not harbor any pathogen. The specific surface area (SSA) and Cd(II) adsorption capacity of 0.75 M KOH modified banana straw biochar (MBBC0.75M) were increased by 247.2% and 46.1% compared to that of PBBC, respectively. Cd(II) adsorption by MBBC0.75M was suitable to be described by the pseudo-second-order kinetic model and Freundlich isotherm. After Cd(II) adsorption, the CdCO3 were confirmed by XRD and observed through SEM. The weakness and shift of oxygen-containing functional groups in MBBC0.75M after Cd(II) adsorption implied that those groups were complexed with Cd(II). The results showed that pyrolysis could not only eliminate banana fusarium wilt, but also prepare porous biochar with the wilt-infected banana straw. The porous biochar possessed the potential to adsorb Cd(II) pollutants.

The essential role of aggregation for the emulsifying ability of a fungal CYS-rich protein.

Biosurfactants are in demand by the global market as natural commodities suitable for incorporation into commercial products or utilization in environmental applications. Fungi are promising producers of these molecules and have garnered interest also for their metabolic capabilities in efficiently utilizing recalcitrant and complex substrates, like hydrocarbons, plastic, etc. Within this framework, biosurfactants produced by two Fusarium solani fungal strains, isolated from plastic waste-contaminated landfill soils, were analyzed. Mycelia of these fungi were grown in the presence of 5% olive oil to drive biosurfactant production. The characterization of the emulsifying and surfactant capacity of these extracts highlighted that two different components are involved. A protein was purified and identified as a CFEM (common in fungal extracellular membrane) containing domain, revealing a good propensity to stabilize emulsions only in its aggregate form. On the other hand, an unidentified cationic smaller molecule exhibits the ability to reduce surface tension. Based on the 3D structural model of the protein, a plausible mechanism for the formation of very stable aggregates, endowed with the emulsifying ability, is proposed. KEY POINTS: • Two Fusarium solani strains are analyzed for their surfactant production. • A cationic surfactant is produced, exhibiting the ability to remarkably reduce surface tension. • An identified protein reveals a good propensity to stabilize emulsions only in its aggregate form.

Mechanism of Fumonisin Self-Resistance: Fusarium verticillioides Contains Four Fumonisin B1-Insensitive-Ceramide Synthases.

Fusarium verticillioides produces fumonisins, which are mycotoxins inhibiting sphingolipid biosynthesis in humans, animals, and other eukaryotes. Fumonisins are presumed virulence factors of plant pathogens, but may also play a role in interactions between competing fungi. We observed higher resistance to added fumonisin B1 (FB1) in fumonisin-producing Fusarium verticillioides than in nonproducing F. graminearum, and likewise between isolates of Aspergillus and Alternaria differing in production of sphinganine-analog toxins. It has been reported that in F. verticillioides, ceramide synthase encoded in the fumonisin biosynthetic gene cluster is responsible for self-resistance. We reinvestigated the role of FUM17 and FUM18 by generating a double mutant strain in a fum1 background. Nearly unchanged resistance to added FB1 was observed compared to the parental fum1 strain. A recently developed fumonisin-sensitive baker's yeast strain allowed for the testing of candidate ceramide synthases by heterologous expression. The overexpression of the yeast LAC1 gene, but not LAG1, increased fumonisin resistance. High-level resistance was conferred by FUM18, but not by FUM17. Likewise, strong resistance to FB1 was caused by overexpression of the presumed F. verticillioides "housekeeping" ceramide synthases CER1, CER2, and CER3, located outside the fumonisin cluster, indicating that F. verticillioides possesses a redundant set of insensitive targets as a self-resistance mechanism.