Substrate For Fungal Growth Research Articles

Soil amendment with biochar and manure alters wood stake decomposition and fungal community composition

AbstractBiochar and manure can be used for sustainable land management. However, little is known about how soil amendments might affect surface and belowground microbial processes and subsequent wood decomposition. In a split‐split‐split plot design, we amended soil with two rates of manure (whole plot; 0 and 9 Mg ha−1) and biochar (split plot; 0 and 10 Mg ha−1). Wood stakes of three species (hybrid poplar, triploid Populus tomentosa Carr.; aspen, Populus tremuloides Michx.; and pine, Pinus taeda L.) were placed in two positions (horizontally on the soil surface, and inserted vertically in the mineral soil), which served as a substrate for fungal growth. In 3 years, the decomposition rate (density loss), moisture content, and fungal community (via high‐throughput sequencing methods) of stakes were evaluated. Results indicated that biochar and/or manure increased the wood stake decomposition rates, moisture content, and operational taxonomic unit abundance. However, the richness and diversity of fungi were dependent on wood stake position (surface > mineral), species (pine > the two Populus), and sample dates. This study highlights that soil amendment with biochar and/or manure can alter the fungal community, which in turn can enhance an important soil process (i.e., decomposition).

Hempcrete as a substrate for fungal growth under high humidity and variable temperature conditions

Bio-based alternatives for existing construction materials can be used to reduce the carbon footprint of the built environment. Hempcrete is one of these materials and is both an excellent hygric/thermal regulator and is carbon negative. However, this novel material is still incompletely researched, especially its fungal growth potential specifically within warm and humid environments. The incorporation of significant biological material within hempcrete can enable it to act as a microbial growth medium, with the corresponding potential for the release of bioaerosols. The aim of this research was thus to investigate the overall practicality of hempcrete implementation in a humid climate. To achieve this, the endogenous fungal genera on a sample of hempcrete were identified, fungal propagules aerosolized from a hempcrete sample enumerated, and a range of temperatures tested to determine their effect on fungi growth determined. Trials were performed to determine whether hempcrete can be effectively decontaminated with common materials to manage microbial growth. Under high humidity, fungal propagule emissions were high with low diversity, with potentially allergenic fungi detected. Disinfection of high fungal load hempcrete samples was able to reduce ∼94% of the fungal observations and reduce aerosolized counts to average background tropical fungal counts. The range of temperatures tested were not found to effect fungal growth, contrary to the consensus of the literature. Overall, these properties make hempcrete suited to humid areas, however, further research to investigate the potential effects of fungi on the material remains lacking.

Improvement of DOPA-Melanin Production by Aspergillus nidulans Using Eco-Friendly and Inexpensive Substrates.

Fungal pigments, including melanin, are recognized as promising materials for biomedical, environmental, and technological applications. In previous studies, we have demonstrated that the DOPA-melanin produced by the MEL1 mutant of Aspergillus nidulans exhibits antioxidant, anti-inflammatory, and antimicrobial activities without any cytotoxic or mutagenic effects, suggesting its potential use in pharmaceuticals. In order to increase the yield of this pigment and reduce the costs of its large-scale production, the present study aimed to evaluate agro-industrial by-products, sugarcane molasses, vinasse, and corn steep liquor as inexpensive substrates for fungal growth using experimental design methodology. According to the results obtained, the optimal composition of the culture medium was 0.81% (v/v) vinasse and 1.62% (w/v) glucose, which promoted a greater production of melanin (225.39 ± 4.52 mg g-1 of biomass), representing a 2.25-fold increase compared with the condition before optimization (100.32 mg.g-1 of biomass). Considering the amount of biomass obtained in the optimized condition, it was possible to obtain a total melanin production of 1 g L-1. Therefore, this formulation of a less complex and low-cost culture medium composition makes the large-scale process economically viable for future biotechnological applications of melanin produced by A. nidulans.

Aspergillus welwitschiae inulinase enzyme cocktails obtained on agro-material inducers for the purpose of fructooligosaccharides production

Production of fructooligosaccharides (FOS) is a trending topic due to their prebiotic effect becoming increasingly important for the modern human diet. The most suitable process for FOS production is the one using fungal inulinases. Introduction of new fungal inulinase producers and their implementation in production of inulinase enzymes is therefore gaining interest. This study provides a new approach to FOS synthesis by fungal enzyme complex without prior separation of any specific enzyme. Inulinase enzyme complexes could be used for the synthesis of FOS in two possible ways – hydrolysis of inulin (FOSh) and transfructosylation process of sucrose (FOSs), as demonstrated here. Depending on the fungal growth inducing substrate, a variety of inulinase enzyme complexes was obtained – one of which was most successful in production of FOSh and another one of FOSs. Substrates derived from crops: triticale, wheat bran, Jerusalem artichoke and Aspergillus welwitschiae isolate, previously proven as safe for use in food, were utilized for production of inulinase enzyme cocktails. The highest FOSs production was obtained by enzyme complex rich in β-fructofuranosidase, while the highest FOSh production was obtained by enzyme complex rich in endoinulinase. Both FOSh and FOSs showed antioxidant potential according to ABTS and ORAC, which classifies them as a suitable additive in functional food. Simultaneous zymographic detection of inulinase enzymes, which could contribute to expansion of the knowledge on fungal enzymes, was developed and applied here. It demonstrated the presence of different inulinase isoforms depending on fungal growth substrate. These findings, which rely on the innate ability of fungi to co-produce all inulinases from a cocktail, could be useful as a new, easy approach to FOS production by fungal enzymes without their separation and purification, contributing to cheaper and faster production processes.

Sugary Foods and Beverages Relationship to Fungal Colonization and Oral Hygiene in School Children

Sugary foods and beverages are highly consumed by children. It is a substrate for fungal growth and has effects on oral hygiene. The study aimed to determine sugary foods and beverages’ relationship to oral fungi and hygiene. This cross-sectional study was conducted on 150 students aged 11-12 years old, selected based on inclusive-exclusive criteria. Demographic data and sugary foods and beverages consumption were recorded in a questionnaire. The oral material was collected and cultured in SDA media. Fungal growth was evaluated microscopically, and then fungal identification used the Integral System YEASTS Plus (Liofilchem®). OHI was used to assess oral hygiene. Results showed that 72.0% were 12 years old, the frequency of sugary foods and beverages consumption was more than once per week in 85 children (56.67 %), mostly girls (30.9%). The fungus found was mostly Candida (55.3%), and 43.3% of children had poor oral hygiene. Statistical analysis showed a significant association between the frequency of sugary foods and beverages consumption with fungal colonization (p<0.05) and oral hygiene (p<0.05). The correlation between fungal colonization and oral hygiene was statistically significant (p<0.05). This study provides insight into the relationships between sugary foods and beverages, fungal colonization, and oral hygiene.

Mushroom Production in the Southern Cone of South America: Bioeconomy, Sustainable Development and Its Current Bloom.

A Sustainable Development Goals (SDGs) based analysis is presented here for business development of the production of edible and medicinal mushrooms using agro-wastes in the Southern Cone of South America. This circular economy approach using edible and medicinal mushroom production on lignocellulosic residues is discussed by analysing both its advantages and drawbacks. Among its main benefits, it is notable that mushroom cultivation using lignocellulosic residues promotes innovation aimed at environmental sustainability, facilitating diversification of the labour supply and the transfer of science to the socio-cultural sphere, which also increases the availability of healthy foods. However, there are some bottlenecks in the process, such as the continuous supply chain of substrates for fungal growth, the lack of equipment and infrastructure for the implementation of cultivation systems in extreme habitats, as well as authorization requirements and other limitations related to a non-fungiphilic culture society. Therefore, this chapter tries to provide key tools for establishing sustainable guidelines for the procurement of local healthy food and other products derived from mushroom cultivation using agricultural residues in the region, which might bloom due to an SDGs-based circular economy approach.

Evaluation of vapor-phase antifungal activities of selected plant essential oils against fungal strains growing on bread food model

The current study aimed to investigate antifungal activities of two commercially available essential oils (EOs), specifically Tea tree oil (Melaleuca alternifolia; TTEO) and St. John's wort oil (Hypericum perforatum; HPEO) against three Penicillium (P.) species: P. citrinum, P. expansum, and P. crustosum in in situ conditions. For this purpose, EOs were applied in the vapor phase to determine the growth inhibition of fungi artificially inoculated on sliced bread. Changes in colony growth rate were evaluated as markers for the mycelial growth inhibition (MGI) effect of the EOs. The antioxidant activities of the EOs were evaluated using the DPPH method. The moisture content (MC) and water activity (aw) of bread as a substrate for fungal growth were also measured. From the DPPH assay, we have found that both EOs (TTEO, HPEO) exhibited strong antioxidant activity (64.94 ±7.34%; 70.36 ±1.57%, respectively). The values for bread MC and aw were 43.01 ±0.341% and 0.947 ±0.006, respectively. Our results suggest that HPEO is the only weak inhibitor of P. citrinum and P. crustosum colony growths. Also, the highest concentrations of TTEO display only the weak capability of mycelial growth inhibition of P. citrinum and P. crustosum. By contrast, the colony growth of P. expansum was enhanced by both EOs at all levels used. In conclusion, the application of both EOs in the vapor phase against selected Penicillium species seems not to be a promising alternative to chemical inhibitors used for bread preservation.

Fungi from dead arthropods and bats of Gomantong Cave, northern Borneo, Sabah (Malaysia)

Borneo is a biodiversity and ecotourism hotspot, yet one of its least-studied ecosystems is their limestone caves. Not many studies have been conducted on the role fungi play in tropical cave ecosystems, and no fungal surveys have been conducted in the caves of Sabah, Malaysia. Here, we assess the mycofloral diversity on bat and arthropod cadavers in one of the most popular ecotourism destinations of northern Borneo, Gomantong caves. Opportunistic sampling of cadavers within the Semud Hitam chamber of Gomantong cave yielded nine dead arthropods and four dead bats. Twenty-four culturable fungi were isolated, of which 14 morphological taxonomic units (MTU) were observed. Twelve of the 14 MTUs underwent molecular characterization of the ITS gene region to confirm identification. All fungi were Ascomycetes except for one Basidiomycete isolate. Aspergillus spp. had the highest occurrence (45.8%), followed by Penicillium spp. (25.0%), and Fusarium sp. (12.5%). Ceratobasidium sp., Diaporthe sp., Pestalotiopsis sp., and Xylaria feejeensis were isolated once each. No more than one fungal taxon was isolated from each arthropod cadaver, and not all arthropods yielded culturable fungi. Bat cadavers yielded 14 out of 24 isolates (58.3%), with the highest occurrence of the fungi sampled from their skin. Our results corroborate that bats and arthropods play a role in fungal dispersion and introduction in the cave because their exteriors are likely to harbor fungi they are exposed to in the environment. We also conclude that cadavers are important substrates for fungal growth and proliferation, perpetuating the role of fungi as important decomposers in caves. This study provides a baseline of information of the mycobiome of Bornean caves for future bioprospecting and potential biotechnological applications.

Combined effects of gamma-irradiation, dose rate and mycobiota activity on cultural heritage – Study on model paper

Cellulose, the main constituent of paper-made objects of cultural heritage (CH), is a favorable substrate for fungal growth. Gamma irradiation is a well-established low-cost treatment convenient for decontamination of such objects. Since side-effects to paper-based CH are always a concern the aim of this work was to investigate if a synergism of microbiological contamination and gamma irradiation effects exists and if it induces changes in paper's appearance and structure. The dose rate plays an important yet generally neglected role in the efficacy of the radiation treatment so another goal was to assert its influence on decontamination efficiency and paper properties.Irradiation conditions for treating the highly resistant secondary colonizer Cladosporium sphaerospermum, as well as the naturally occurring mycobiota were evaluated. Untreated and inoculated samples of paper were irradiated with doses commonly applied to CH objects, as well as to significantly higher doses, at two dose rates that differ for two orders of magnitude. Microbiological analysis of irradiated samples was conducted. Colorimetric analysis, UV-vis and FTIR measurements were performed after short lived reaction species have decayed.The results have shown that in the case of high contaminations (104 CFU/g) the applied dose needs to be adjusted and that the corresponding dose rate needs to be high enough. While at the dose rate of 31 kGy/h the irradiation dose of 7 kGy seems to be effective to obtain proper reduction of mycobita, at the dose rate that was two orders of magnitude lower the required dose increased approximately ten times. Thus the reevaluation of the recommended dose of 8 ± 2 kGy is needed. Considering the side effects of radiation treatment the dose rate effect has also been observed. At the higher of the investigated dose rates the irradiation doses needed for decontamination did not alter the appearance of paper, while at the lower one the changes were hardly perceptible. The main species showing their contribution to color change were the carbonate anion-radicals that were formed on the CaCO3 paper filler. No oxidation or change in crystallinity of cellulose was detected. Overall changes were too insignificant to make any conclusion on the contribution of mycobiota to the irradiation side-effects on the paper under the studied conditions.

Aspergillus fumigatus biofilm formation on different bone substitutes used in maxillary sinus augmentation: an in vitro analysis

BackgroundFungus ball (FB) typically affects healthy adults, and Aspergillus fumigatus is the most frequent etiologic agent: iatrogenic factors represent an important issue in FB pathogenesis. Moreover, a recent study suggested a significant association between the use of anorganic bovine bone as sinus grafting material and subsequent development of FB. The aim of the present investigation is to evaluate in vitro eventual differences in the ability of Aspergillus fumigatus to colonize different bone grafting materials and grow on them as biofilm.FindingsFive different bone substitutes (demineralized bone matrix, anorganic bovine bone, ß-tricalcium phosphate, synthetic nano-hydroxyapatite, and synthetic hydroxyapatite), commonly used in sinus floor augmentation procedures, were inoculated with conidia suspensions of A. fumigatus and incubated at 37 °C for 4 and 8 h, in standardized conditions. Biofilm bound to the different materials underwent quantitative and qualitative analysis by confocal and scanning electron microscopy. A. fumigatus proved to be able to adhere and form biofilm on all the tested bone substitutes. The surface plot representation of the samples displayed some differences in the density of the superficial layer, due to the physical characteristics of the biomaterials. Nevertheless, Kruskal–Wallis test showed no significant differences in biomass amount among the five bone substitutes (p = 0.236 and p = 0.55 after 4 and 8 h adhesion, respectively).ConclusionsAll the bone substitutes normally used in sinus floor augmentation represent a favorable substrate for fungal growth, due to their physical and chemical characteristics. During sinus floor elevation procedures, Schneiderian membrane integrity should be maintained in order to avoid the exposure of the grafting material at the respiratory environment, with potential risks of fungal colonization.

Amblypygid-fungal interactions: The whip spider exoskeleton as a substrate for fungal growth

Fungi and arthropods represent some of the most diverse organisms on our planet, yet the ecological relationships between them remain largely unknown. In animals, fungal growth on body surfaces is often hazardous and is known to cause mortality. In contrast, here we report the presence of an apparently non-harmful mycobiome on the cuticle of whip spiders (Arachnida: Amblypygi). The associations are not species-specific and involve a diversity of fungal species, including cosmopolitan and local decomposers as well as entomopathogens. We discuss the ecology of the detected fungal species and hypothesize that the thick epicuticular secretion coat of whip spiders (the cerotegument) promotes fungal growth. It is possible that this relationship is beneficial towards the host if it leads to parasite control or chemical camouflage. Our findings, which are the first from this arthropod lineage, indicate that non-pathogenic interactions between arthropods and fungi may be much more widespread than predicted and call for more studies in this area.

Identification of Penicillium species by MALDI-TOF MS analysis of spores collected by dielectrophoresis.

In matrix-assisted laser-desorption and ionization mass spectrometry, spectral differences are frequently observed using different growth media on agar plates and/or different growth times in culture, which add undesirable analytical variance. In this article, we explore an approach to the above problem based upon the rationale that, while protein expression in fungal mycelium may well vary under different growth conditions, this might not apply to the same extent in fungal spores. To this end, we have exploited the fact that while mycelium is generally anchored to the fungal-growth substrate, some fungi produce physically-isolated spores which, as such, are amenable to manipulation using dielectrophoresis (the translational motion of charged or uncharged matter caused by polarization effects in a non-uniform electrical field). Such fields can be conveniently generated through the charging of an insulator using the triboelectric effect (the transfer of charge between two objects through friction when they are rubbed together). In this study, polystyrene microbiological inoculating loops were used in combination with nylon-fabric rubbing to harvest fungal spores from five species from within the genus Penicillium, which were grown on agar plates containing two different media over an extended time course. In terms of average Bruker spectral-comparison scores, our method generated higher scores in 80% of cases tested and, in terms of average coefficients of variation, our method generated lower spectral variability in 93% of cases tested. Harvesting of spores using a rapid, inexpensive and simple dielectrophoretic method, therefore, facilitates improved fungal identification for the Penicillium species tested.

Pinus taedaL. response to differential inoculum density ofLeptographium terebrantiscolonized toothpicks

AbstractBark beetle‐vectored ophiostomatoid fungi,Leptographium terebrantis, is inoculated on the roots and lower stems of stressedPinusspecies during the feeding activity of bark beetle. To determine the exact host response following inoculation, it is critical to challenge the host with a realistic amount of fungal inoculum. Thus, we designed a series of stepwise experiments usingL. terebrantiscolonized toothpicks which focused on the inoculum transfer from the toothpicks to excisedPinus taedastem segments and living saplings, respectively, at different inoculum densities. The toothpicks served as a substrate for fungal growth and sporulation and the inoculation showed their utility in eliciting host's response to the pathogen. The inoculated fungus caused blue‐stain and sapwood occlusions inP. taedastems and saplings, respectively. The volume of occluded, visually damaged sapwood increased by 1.96 cm3per radial inoculation point on average. Fungal colonized toothpicks can be used as a suitable alternative to agar discs for studying bark beetles vectored fungi and their host interactions.

Secondary metabolite production by cereal-associated penicillia during cultivation on cereal grains.

Cereals are vulnerable substrates for fungal growth and subsequent mycotoxin contamination. One of the major fungal genera to colonize the ecosystem of stored grain is Penicillium, especially species in the series of Viridicata and Verrucosa. Culturing these species on grains, we hoped to induce the production of relevant secondary metabolites produced by these fungi in the early stage of cereal breakdown. In a multivariate setup six different cereal grains (wheat, rye, barley, oat, rice, and maize), one kind of white beans, and two standard fungal media, Yeast Extract Sucrose agar (YES agar) and Czapek Yeast Autolysate agar (CYA agar), were inoculated with the ten most important cereal-associated species from Penicillium (P. aurantiogriseum, P. cyclopium, P. freii, P. melanoconidium, P. neoechinulatum, P. polonicum, P. tricolor, P. viridicatum, P. hordei, and P. verrucosum). P. nordicum is a meat-associated species, which was included due to its chemical association with P. verrucosum, in addition to see if a substrate change would alter the profile of known chemistry. We found that cereals function very well as substrates for secondary metabolite production, but did not present significantly different secondary metabolite profiles, concerning known chemistry, as compared to standard laboratory agar media. However, white beans altered the semi-quantitative secondary metabolite profiles for several species. Correlations between substrates and certain metabolites were observed, as illuminated by principal component analysis. Many bioactive secondary metabolites were observed for the first time in the analyzed fungal species, including ergot type alkaloids in P. hordei.

Identification of the Achilles heels of the laurel wilt pathogen and its beetle vector

Ambrosia beetles harbor fungal symbionts that serve as food sources for larvae and adults. These beetles lay their eggs along tunnels in xylem sapwood, which is the substrate for fungal growth. Symbiotic fungi of the genus Raffaelea found in invasive and indigenous ambrosia beetles include the highly virulent plant pathogen Raffaelea lauricola affecting members of the Lauraceae family. R. lauricola is responsible for the deaths of > 500 million trees since 2005. Infection by as few as 100 spores can kill a healthy tree within months. Our data show that R. lauricola is cold-adapted with optimal growth between 16 and 26°C, with little to no growth at temperatures ≥ 30°C. The fungus is halophilic and shows a dramatic decrease in growth at pH ≥ 6.8. Fungicide resistance profiling revealed sensitivity of R. lauricola to prochloraz, dichlorofluanid, most conazoles, dithiocarbamates, and zineb (zinc fungicide), whereas the related species Raffaelea arxii showed more limited fungicide sensitivity. Entomopathogenic fungi potentially useful for beetle control were generally highly resistant to most fungicides tested. Coupling pH decreased the concentration for 95% inhibition of fungal growth (IC95) of the most potent R. lauricola fungicides by 3-4-fold. Use of avocado bark plug insect bioassays revealed that commercially available Beauveria bassiana can be used as a biological control agent capable of effectively killing the beetle vectors. These data provide simple and practical recommendations to specifically target R. lauricola while having minimal effects on other symbiotic and entomopathogenic fungi, the latter of which can be used to manage the beetle vectors.

Peanuts, Aflatoxins and Undernutrition in Children in Sub-Saharan Africa.

Peanuts (Arachis hypogaea) is an important and affordable source of protein in most of Sub-Saharan Africa (SSA) and a popular commodity and raw material for peanut butter, paste and cooking oil. It is a popular ingredient for foods used at the point of weaning infants from mother’s milk. It is at this critical point that childhood undernutrition occurs and the condition manifests as stunting, wasting and growth restriction and accounts for nearly half of all deaths in children under five years of age in SSA. Undernutrition is multi-factorial but weaning foods contaminated with microbiological agents (bacteria and fungi) and natural toxins have been shown to play a big part. While peanuts may provide good nutrition, they are also highly prone to contamination with mycotoxigenic fungi. The high nutritive value of peanuts makes them a perfect substrate for fungal growth and potential aflatoxin contamination. Aflatoxins are highly carcinogenic and mutagenic mycotoxins. This article reviews the nutritional value and aflatoxin contamination of peanuts, the role they play in the development of childhood malnutrition (including the different theories of aetiology) and immunological problems in children. We also discuss the control strategies that have been explored and advocacy work currently taking shape in Africa to create more awareness of aflatoxins and thus combat their occurrence with the goal of reducing exposure and enhancing trade and food safety.

Fungos e aflatoxinas no arroz: ocorrência e significado na saúde do consumidor

Resumo O arroz é um dos cereais mais consumidos no Brasil e no mundo. Devido ao grande impacto do consumo de arroz na população, estudos sobre a qualidade deste produto são de grande importância. É um ótimo substrato para a produção de micotoxinas e, quando os fungos toxigênicos encontram condições de crescer e produzir toxinas, estes as produzem em grandes quantidades. Embora não seja comum a presença de micotoxinas, existem alguns relatos sobre a ocorrência de aflatoxinas e fungos aflatoxigênicos no arroz. O presente artigo é uma revisão sobre os aspectos gerais do arroz, sua produção, ocorrência de fungos, aflatoxinas e micotoxinas no Brasil e no mundo, bem como sobre a redução de aflatoxinas durante o processamento do arroz.

Utilisation of Jatropha press cake as substrate in biomass and lipase production from Aspergillus niger 65I6 and Rhizomucor miehei CBS 360.62

Jatropha curcas L. is a tropical plant that grows well on poor soils in arid regions and produces oil-rich, unedible seeds. The oil from these seeds can be used in the production of biodiesel. In addition, the press-cake waste that is left after oil extraction contains approximately 40% of protein. The use of Jatropha press-cake as substrate for fungal growth and the production of lipase by Aspergillus niger 65I6 isolated from Indonesia and Rhizomucor miehei CBS 260.62 was investigated. Hydrolysis of the press-cake using 2.5% sodium hydroxide for 45 min was found to be the best pre-treatment method indicated by a high lipase activity. The alkaline hydrolysis increased the amount of reducing sugars and soluble protein to 133.3% and 40% of the initial amount, respectively. 5.7% of the protein fraction was hydrolysed by the alkaline pretreatment. The alkaline hydrolysed Jatropha press-cake was used as a growth substrate for A. niger 65I6 and R. miehei CBS 360.62. Both fungi grew well on the hydrolysed press cake. The addition of glucose or maltodextrin gave a substantial increase in fungal biomass but inhibited the lipase production, very likely due to catabolite repression by the sugars.

Evolution of fungal population and mycotoxins in sorghum silage

ABSTRACTSilage, one of the most important feed sources for cattle, is vulnerable to contamination by spoilage moulds and mycotoxins because ensilage materials are excellent substrates for fungal growth. The aim of this study was to identify the mycobiota of sorghum silages, to determine the presence of aflatoxins and fumonisins, and to correlate these results with physical parameters of the silage. A total of 275 samples of sorghum were collected from dairy farms in the south-west region of Uruguay were silage practices are developed. The presence of fungi was observed in all of the sorghum samples with values varying from 0.2 × 104 to 4085 × 104 UFC g−1. Significant difference were detected in the total number of fungi during the storage period; at six months there is a high risk of fungal spoilage. The most frequent genera isolated from sorghum samples were Penicillium (70%), Aspergillus (65%), Absidia (40%), Fusarium (35%), Paecilomyces (35%) and Alternaria, Cladosporium, Gliocadium and Mucor (30%). The toxigenic species most frequently found were Penicillium citrinum, Aspergillus flavus and Fusarium nygamai. Only two samples were contaminated by AFB1 with levels of 1 and 14 µg kg–1. Fumonisin was detected in 40% of freshly harvest samples with levels ranged from 533 µg kg–1 to 933 µg kg–1. The use of silo bags seems to be an effective tool to store sorghum. However, the presence of toxigenic fungi show that regular screening for mycotoxins levels in silages must be performed to avoid the exposure of animals to contaminated feed and the introduction of these compounds into the food chain.

Fusarium and Aspergillus mycotoxins contaminating wheat silage for dairy cattle feeding in Uruguay.

Wheat is one of the most important cultivated cereals in Uruguay for human consumption; however, when harvest yields are low, wheat is usually used in ensiling for animal feeding. Ensiling is a forage preservation method that allows for storage during extended periods of time while maintaining nutritional values comparable to fresh pastures. Silage is vulnerable to contamination by spoilage molds and mycotoxins because ensilage materials are excellent substrates for fungal growth. The aim of the study was to identify the mycobiota composition and occurrence of aflatoxins and DON from wheat silage. A total of 220 samples of wheat were collected from four farms in the southwest region of Uruguay were silage practices are developed. The main fungi isolated were Fusarium (43%) and Aspergillus (36%), with Fusarium graminearum sensu lato and Aspergillus section Flavi being the most prevalent species. Aflatoxin concentrations in silo bags ranged from 6.1 to 23.3 μg/kg, whereas DON levels ranged between 3000 μg/kg and 12,400 μg/kg. When evaluating aflatoxigenic capacity, 27.5% of Aspergillus section Flavi strains produced AFB1, 5% AFB2, 10% AFG1 and 17.5% AFG2. All isolates of F. graminearum sensu lato produced DON and 15-AcDON. The results from this study contribute to the knowledge of mycobiota and mycotoxins present in wheat silage.