Mycotoxin risk evaluation in feeds contaminated by Aspergillus fumigatus

DNA metabarcoding uncovers fungal communities in Zingiberis Rhizoma

Objective

Zingiberis Rhizoma (ZR, Ganjiang in Chinese), also known as dried ginger, is a popular spice and medicinal herb that has been used for several thousand years. However, ZR is easily contaminated by fungi and mycotoxin under suitable conditions, and might be hazardous to the health and safety of consumers, thus concerns about the herb's safety have been raised. The aim of this study was to investigate the fungal community and the effects of collection areas and processing methods on the fungal community in ZR.

Methods

A total of 18 ZR samples were collected from four provinces of China, and the samples were divided into four groups based on collecting sites. Meanwhile, the samples collected in Sichuan Province, China were divided into three groups based on the processing methods. We employed the Illumina MiSeq PE300 platform and targeted the internal transcribed spacer 2 (ITS2) sequences to investigate fungal contamination in ZR samples, and the difference in fungal community among the groups of different collection sites and processing methods.

Results

All 18 samples were contaminated with fungi. Ascomycota was the dominant phyla, accounting for 34.46%-100% of the fungal reads. At the genus level, Candida, Diutina, and Aspergillus were the most dominant genera, with relative abundances of 0-98.37%, 0-99.82%, and 0-79.08%, respectively. Meanwhile, four potential toxigenic fungi and seven human pathogens were found. Furthermore, differences in the community composition of ZR samples from four collecting sites and three processing methods were observed.

Conclusion

DNA metabarcoding provides a novel insight into fungal community diversity in ZR samples, providing references to ensure the sustainable utilization and quality research of ZR.

An overview of mycotoxicoses in rabbits

Mycotoxicoses are usually a consideration in large animal species but can affect companion animals as well. Due to increasing interest and the ease of using rabbits as laboratory models, a growing number of published experimental studies discuss the effects of various mycotoxins on this species. However, the available evidence is fragmented and heterogeneous, and has not recently been collated in a review, to my knowledge. Although mycotoxicoses in rabbits are typically subclinical, clinical signs can include weight loss, anorexia, gastrointestinal disorders, stunted growth, reproductive abnormalities, and susceptibility to infections. An antemortem diagnosis typically relies on a comprehensive clinical history, and assessment of clinical signs and relevant laboratory findings, with confirmation of exposure achieved through the measurement of mycotoxin concentrations in feed or target organs. My review focuses on the clinicopathologic and histopathologic effects of the mycotoxins most important in rabbits, including fumonisins, ochratoxins, aflatoxins, trichothecenes, and zearalenone. This review offers a thorough overview of the effects of mycotoxins in rabbits, serving as a one-stop resource for veterinary practitioners, diagnosticians, and researchers.

Review: Strategies and technologies in preventing regulated and emerging mycotoxin co-contamination in forage for safeguarding ruminant health

Ruminants are often considered less susceptible to mycotoxins than monogastrics, owing to rumen microflora converting mycotoxins to less toxic compounds or several compounds present in the rumen-reticulum compartment, being able to bind the mycotoxin "mother" molecule that make them unavailable for absorption process in the gastro-intestinal tract of host animals. However, if ruminants consume feed contaminated by mycotoxins for long periods, their growth, development, and fertility can be compromised. Among regulated mycotoxins, the most studied and known for their effects are aflatoxins (AFs) AFB1, AFB2, AFG1 and AFG2, as well as the AFM1 for its high importance in dairy sector, deoxynivalenol (DON) and its metabolites 3/15 acetyl-DON and 3-glucoside DON, T-2 and HT-2 toxins, zearalenone, fumonisins, in particular that belong to the B class, and ochratoxin A. Furthermore, because of the emergence of multiple emerging mycotoxins that are detectable in feed utilised in ruminant diets, such as ensiled forage, there is now a growing focus on investigating these compounds by the scientific community to deepen their toxicity for animal health. Despite the enhancement of research, it is remarkable that there is a paucity of in vivo trials, as well as limited studies on nutrient digestibility and the impact of these molecules on rumen and intestinal functions or milk yield and quality. In this review, recent findings regarding the occurrence of regulated and emerging mycotoxins in forage and their possible adverse effects on dairy cattle are described, with special emphasis on animal performance and on rumen functionality.

Comparison of microscopic and metagenomic approaches to identify cereal pathogens and track fungal spore release in the field

Wheat is one of the main staple food crops, and 775 million tonnes of wheat were produced worldwide in 2022. Fungal diseases such as Fusarium head blight, Septoria tritici blotch, spot blotch, tan spot, stripe rust, leaf rust, and powdery mildew cause serious yield losses in wheat and can impact quality. We aimed to investigate the incidence of spores from major fungal pathogens of cereals in the field by comparing microscopic and metagenomic based approaches for spore identification. Spore traps were set up in four geographically distinct UK wheat fields (Carnoustie, Angus; Bishop Burton, Yorkshire; Swindon, Wiltshire; and Lenham, Kent). Six major cereal fungal pathogen genera (Alternaria spp., Blumeria graminis, Cladosporium spp., Fusarium spp., Puccinia spp., and Zymoseptoria spp.) were found using these techniques at all sites. Using metagenomic and BLAST analysis, 150 cereal pathogen species (33 different genera) were recorded on the spore trap tapes. The metagenomic BLAST analysis showed a higher accuracy in terms of species-specific identification than the taxonomic tool software Kraken2 or microscopic analysis. Microscopic data from the spore traps was subsequently correlated with weather data to examine the conditions which promote ascospore release of Fusarium spp. and Zymoseptoria spp. This revealed that Zymoseptoria spp. and Fusarium spp. ascospore release show a positive correlation with relative humidity (%RH). Whereas air temperature (°C) negatively affects Zymoseptoria spp. ascospore release.

Fist report on fumagillin production by Aspergillus fumigatus sensu stricto gliotoxigenic strains recovered from raw cow milk and clinical samples in Argentina

In Argentina there are no reports on Aspergillus fumigatus fumagillin-producing strains. In this study we describe the isolation and mycotoxin production capacity of ten A. fumigatus strains isolated from farm and clinical samples. Farm strains were isolated from milk samples taken from dairy cows in Córdoba province, some of which were associated with subclinical mastitis. A culture medium was defined to optimize fumagillin production and a detection method was developed by HPLC chromatography. It is known that in addition to the host immune status, strain virulence is a fundamental characteristic that will determine its pathogenicity and, in this sense, fumagillin is considered to be among the virulence factors. In the present work, all the strains tested for the production of fumagillin were able to synthesize it, highlighting that the strain A. fumigatus RC2243, from a milk sample from a cow with clinical mastitis, was the most productive. The existence of fumagillin-producing strains represents a potential risk of mycotoxins being transferred to raw milk, constituting a public health risk.

Therapeutic Potential of Green Synthesized Gold Nanoparticles Using Extract of Leptadenia hastata against Invasive Pulmonary Aspergillosis

Gold nanoparticles are widely used in the biomedical field for the treatment of several diseases, including cancer, inflammatory diseases, and immune system disorders, due to their distinctive physicochemical characteristics. In this study, we investigated the therapeutic potential of green synthesized gold nanoparticles using ethanolic leaf extract of Leptadenia hastata (LH-AuNPs) against invasive pulmonary aspergillosis (IPA) in mice. UV/visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and zeta potential were used to characterize the biofabricated LH-AuNPs. Antifungal activity of LH-AuNPs was determined by MTT assay, (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide), time-kill assay, and radial growth inhibition. TEM and SEM were used to examine the mode of the antifungal action of LH-AuNPs. The in vivo activity of LH-AuNPs against IPA was studied using a well-established IPA mouse model. LH-AuNPs excreted antifungal activity against Aspergillus fumigatus with MIC 64 µg/mL and inhibited the radial growth of A. fumigatus by 30% compared to the control. LH-AuNPs caused distortion and collapse of fungal hyphae and deterioration of cell walls. Interestingly, LH-AuNPs did not display any cytotoxicity on cultured primary bone marrow stem cells (BMSCs) or A549 human lung cell line in vitro at MIC concentration. IPA mice treated with LH-AuNPs displayed significant lung tissue repair without any in vivo cytotoxicity. LH-AuNPs administration showed significant suppression of fungal burden and gliotoxin production in the lung. In addition, LH-AuNPs inhibited IPA-induced pro-inflammatory cytokines production, including interleukin-1 (IL-1), interleukin-17 (IL-17), and tumor necrosis factor-alpha (TNF-α), and reduced oxidative stress in lung. In conclusion, our data provide LH-AuNPs as a novel nanoparticle therapy for IPA.

Co-Occurrence of Regulated and Emerging Mycotoxins in Corn Silage: Relationships with Fermentation Quality and Bacterial Communities

Sixty-four corn silages were characterized for chemicals, bacterial community, and concentrations of several fungal metabolites. Silages were grouped in five clusters, based on detected mycotoxins, and they were characterized for being contaminated by (1) low levels of Aspergillus- and Penicillium-mycotoxins; (2) low levels of fumonisins and other Fusarium-mycotoxins; (3) high levels of Aspergillus-mycotoxins; (4) high levels of non-regulated Fusarium-mycotoxins; (5) high levels of fumonisins and their metabolites. Altersetin was detected in clusters 1, 3, and 5. Rugulusovin or brevianamide F were detected in several samples, with the highest concentration in cluster 3. Emodin was detected in more than 50.0% of samples of clusters 1, 3 and 5, respectively. Kojic acid occurred mainly in clusters 1 and 2 at very low concentrations. Regarding Fusarium mycotoxins, high occurrences were observed for FB3, FB4, FA1, whereas the average concentrations of FB6 and FA2 were lower than 12.4 µg/kg dry matter. Emerging Fusarium-produced mycotoxins, such as siccanol, moniliformin, equisetin, epiequisetin and bikaverin were detected in the majority of analyzed corn silages. Pestalotin, oxaline, phenopirrozin and questiomycin A were detected at high incidences. Concluding, this work highlighted that corn silages could be contaminated by a high number of regulated and emerging mycotoxins.

Modelling the effect of pH and water activity in the growth of Aspergillus fumigatus isolated from corn silage

AIMS

The aim of this work was to use mathematical kinetic modelling to assess the combined effects of a_W, pH, O₂ availability and temperature on the growth rate and time to growth of Aspergillus fumigatus strains isolated from corn silage.

METHODS AND RESULTS

A full factorial design was used in which two factors were assayed: pH and a_W . The a_W levels assayed were 0·80, 0·85, 0·90, 0·92, 0·94, 0·96, 0·98 and 0·99. The levels of pH assayed were 3·5, 4, 4·5, 5, 6, 7, 7·5 and 8. The assay was performed at normal oxygen tension at 25 and 37°C, and at reduced oxygen tension at 25°C. Two strains of A. fumigatus isolated from corn silage were used. Kinetic models were built to predict growth of the strain under the assayed conditions. The cardinal models gave a good quality fit for radial growth rate data. The results indicate that the environmental conditions which take place during silage production, while limiting the growth of most micro-organisms, would not be able to control A. fumigatus. Moreover, pH levels in silage, far from limiting its growth, are also close to its optimum. Carbon dioxide at 5% in the environment did not significantly affect its growth.

CONCLUSIONS

A need for a further and controlled acidification of the silage exists, as no growth of A. fumigatus was observed at pH 3·5, as long as the organoleptic characteristics of the silage are not much compromised.

SIGNIFICANCE AND IMPACT OF THE STUDY

Aspergillus fumigatus is one of the major opportunistic pathogens able to cause illness such as allergic bronchopulmonary aspergillosis, aspergilloma and invasive aspergillosis to rural workers. Exposure of animals to A. fumigatus spores can result in infections, particularly in those organs exposed to external invasion, such as the airways, mammary gland and uterus at birth.

Occurrence, prevention and remediation of toxigenic fungi and mycotoxins in silage: a review

Ruminants are considered to be less sensitive towards mycotoxins than monogastric animals because rumen microbiota have mycotoxin-detoxifying capacities. Therefore the effect of mycotoxins towards ruminants has been studied to a lesser extent compared with monogastric animals. Worldwide, a high proportion of the ruminant diet consists of silages made of forage crops (i.e. all parts of the crop above the stubble are harvested). In practice, silages are often contaminated with multiple mycotoxins. Exposure to a cocktail of mycotoxins can hamper animal production and have severe health consequences. In this article the different aspects associated with mycotoxin contamination of silage are reviewed 'from seed to feed'. An overview is given on the occurrence of toxigenic fungal species and their concomitant mycotoxins in forage crops before and after ensiling. The mycotoxin load of visually non-mouldy samples and mouldy hot spots within the same silo is also compared. Subsequently, this review delves into different problem-solving strategies. A logical first step is prevention of mould growth and mycotoxin production in the field, during harvest and during ensiling. If prevention should fail, several remediation strategies are available. These are listed, mainly focusing on the possibilities of microbial degradation of mycotoxins in vivo in silage. © 2015 Society of Chemical Industry.

Mycotoxins in silage: checkpoints for effective management and control

Silage has a substantial role in ruminant nutrition. Silages as a source of mycotoxigenic fungi and mycotoxins merit attention. Fungal growth and mycotoxin production before and during storage are a well-known phenomenon, resulting in reduced nutritional value and a possible risk factor for animal health. Mycotoxin co-contamination seems to be unavoidable under current agricultural and silage-making practices. Multi-mycotoxin contamination in silages is of particular concern due to the potential additive or synergistic effects on animals. In regard to managing the challenge of mycotoxins in silages, there are many factors with pre- and post-harvest origins to take into account. Pre-harvest events are predominantly dictated by environmental factors, whereas post-harvest events can be largely controlled by the farmer. An effective mycotoxin management and control programme should be integrated and personalised to each farm at an integrative level throughout the silage production chain. Growing crops in the field, silage making practices, and the feed out phase must be considered. Economical and straightforward silage testing is critical to reach a quick and sufficiently accurate diagnosis of silage quality, which allows for ‘in field decision-making’ with regard to the rapid diagnosis of the quality of given forage for its safe use as animal feed. Regular sampling and testing of silage allow picking up any variations in mycotoxin contamination. The use of rapid methods in the field represents future challenges. Moreover, a proper nutritional intervention needs to be considered to manage mycotoxin-contaminated silages. At farm level, animals are more often exposed to moderate amounts of several mycotoxins rather than to high levels of a single mycotoxin, resulting more frequently in non-specific digestive and health status impairment. Effective dietary strategies to promote rumen health, coupled with the administration of effective and broad-spectrum mycotoxin detoxifiers, are essential to minimise the negative impact of mycotoxins.

Review on Mycotoxin Issues in Ruminants: Occurrence in Forages, Effects of Mycotoxin Ingestion on Health Status and Animal Performance and Practical Strategies to Counteract Their Negative Effects

Ruminant diets include cereals, protein feeds, their by-products as well as hay and grass, grass/legume, whole-crop maize, small grain or sorghum silages. Furthermore, ruminants are annually or seasonally fed with grazed forage in many parts of the World. All these forages could be contaminated by several exometabolites of mycotoxigenic fungi that increase and diversify the risk of mycotoxin exposure in ruminants compared to swine and poultry that have less varied diets. Evidence suggests the greatest exposure for ruminants to some regulated mycotoxins (aflatoxins, trichothecenes, ochratoxin A, fumonisins and zearalenone) and to many other secondary metabolites produced by different species of Alternaria spp. (e.g., AAL toxins, alternariols, tenuazonic acid or 4Z-infectopyrone), Aspergillus flavus (e.g., kojic acid, cyclopiazonic acid or β-nitropropionic acid), Aspergillus fuminatus (e.g., gliotoxin, agroclavine, festuclavines or fumagillin), Penicillium roqueforti and P. paneum (e.g., mycophenolic acid, roquefortines, PR toxin or marcfortines) or Monascus ruber (citrinin and monacolins) could be mainly related to forage contamination. This review includes the knowledge of mycotoxin occurrence reported in the last 15 years, with special emphasis on mycotoxins detected in forages, and animal toxicological issues due to their ingestion. Strategies for preventing the problem of mycotoxin feed contamination under farm conditions are discussed.

Increased production of gliotoxin is related to the formation of biofilm by Aspergillus fumigatus: an immunological approach

Gliotoxin (GT) belongs to the epipolythiodioxopiperazine class of toxins secreted from certain fungi including Aspergillus fumigatus, which is the most prolific producer of this secondary metabolite. Recently, enhanced amounts of GT were found in in vitro biofilm-grown A. fumigatus mycelium. To further correlate the A. fumigatus biofilm growth phenotype with the enhanced secretion of GT, a polyclonal antibody (pAb) was produced by immunizing mice against GT. By an indirect immunofluorescent assay, pAb was then able to recognize specifically GT onto A. fumigatus Af293 biofilm formed on human pulmonary epithelial cells. Then, treating Af293 biofilms with a compound which reduces the GT disulfide bonds provoked shutdown of the GT-specific immunofluorescence (IF) signals along the hyphae. To explore the potential of GT for diagnostic use, pAb was shown to react with GT on hyphae into Aspergillus culture-positive respiratory tract specimens from patients with probable invasive aspergillosis (IA) and into tissue specimens from the lungs of patients with proven IA. As the presence of fungal hyphae in clinical specimens strongly indicates the in vivo A. fumigatus growth as a biofilm, anti-GT antibodies could be a specific and sensitive diagnostic tool for detecting A. fumigatus biofilm-associated clinical infections.

New untargeted metabolic profiling combining mass spectrometry and isotopic labeling: application on Aspergillus fumigatus grown on wheat

Characterization of fungal secondary metabolomes has become a challenge due to the industrial applications of many of these molecules, and also due to the emergence of fungal threats to public health and natural ecosystems. Given that, the aim of the present study was to develop an untargeted method to analyze fungal secondary metabolomes by combining high-accuracy mass spectrometry and double isotopic labeling of fungal metabolomes. The strain NRRL 35693 of Aspergillus fumigatus , an important fungal pathogen, was grown on three wheat grain substrates: (1) naturally enriched grains (99% (12)C), (2) grains enriched 96.8% with (13)C, (3) grains enriched with 53.4% with (13)C and 96.8% with (15)N. Twenty-one secondary metabolites were unambiguously identified by high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) analysis. AntiBase 2012 was used to confirm the identity of these metabolites. Additionally, on the basis of tandem mass spectrometry (MS(n)) experiments, it was possible to identify for the first time the formula and the structure of fumigaclavine D, a new member of the fumigaclavines family. Post biosynthesis degradation of tryptoquivaline F by methanol was also identified during HPLC-HRMS analysis by the detection of a carbon atom of nonfungal origin. The interest of this method lies not only on the unambiguous determination of the exact chemical formulas of fungal secondary metabolites but also on the easy discrimination of nonfungal products. Validation of the method was thus successfully achieved in this study, and it can now be applied to other fungal metabolomes, offering great possibilities for the discovery of new drugs or toxins.

Culture condition-dependent metabolite profiling of Aspergillus fumigatus with antifungal activity

Three sections of Aspergillus (five species, 21 strains) were classified according to culture medium-dependent and time-dependent secondary metabolite profile-based chemotaxonomy. Secondary metabolites were analysed by liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI-MS-MS) and multivariate statistical methods. From the Aspergillus sections that were cultured on malt extract agar (MEA) and Czapek yeast extract agar (CYA) for 7, 12, and 16 d, Aspergillus sections Fumigati (A. fumigatus), Nigri (A. niger), and Flavi (A. flavus, A. oryzae, and A. sojae) clustered separately on the basis of the results of the secondary metabolite analyses at 16 d regardless of culture medium. Based on orthogonal projection to latent structures discriminant analysis by partial least squares discriminant analysis (PLS-DA), we identified the secondary metabolites that helped differentiate sections between A. fumigatus and Aspergillus section Flavi to be gliotoxin G, fumigatin oxide, fumigatin, pseurotin A or D, fumiquinazoline D, fumagillin, helvolic acid, 1,2-dihydrohelvolic acid, and 5,8-dihydroxy-9,12-octadecadienoic acid (5,8-diHODE). Among these compounds, fumagillin, helvolic acid, and 1,2-dihydrohelvolic acid of A. fumigatus showed antifungal activities against Malassezia furfur, which is lipophilic yeast that causes epidermal skin disorders.

Gliotoxin contamination in and pre- and postfermented corn, sorghum and wet brewer's grains silage in Sao Paulo and Rio de Janeiro State, Brazil

AIMS

The aim of this study was to determine total fungal counts and the relative density of Aspergillus fumigatus and related species in silage samples intended for bovines before and after fermentation as well as to monitor the natural occurrence of gliotoxin in silage samples (pre- and postfermentation).

METHODS AND METHODS

The survey was performed in farms located in São Paulo and Rio de Janeiro States in Brazil. In addition, the ability of A. fumigatus strains and related species strains to produce gliotoxin was also evaluated. A total of 300 samples were taken, immediately after opening of the silo (3-5 months) and during the ensiling period. Fungal counts were done by the surface-spread method. Gliotoxin production ability of isolates and natural contamination were determined by HPLC.

RESULTS

All postfermented samples had a total number of moulds exceeding 1 × 10(4) CFU g(-1), with Aspergillus sp. as the most prevalent genus. Frequency of strains, among A. fumigatus and related species, was able to produce gliotoxin was similar in pre- and postfermented samples, except for sorghum, which showed differences between both kinds of samples. The highest toxin levels were produced by strains isolated from postfermented samples. More than 50% of the samples showed gliotoxin contamination levels that exceeded concentrations known to induce immunosuppressive and apoptotic effects in cells.

CONCLUSIONS

The present data suggest that care should be taken because gliotoxin contamination in feedstuffs could affect productivity and also present a health risk for herds.

SIGNIFICANCE AND IMPACT OF THE STUDY

Gliotoxin was found at quite important concentrations levels in pre- and postfermented substrates and its presence could therefore probably affect the productivity and health of herds. Current conservation and management practices do not avoid contamination with A. fumigatus on silage. Therefore, farm workers should be adequately protected during its handling.

How to improve the hygienic quality of forages for horse feeding

BACKGROUND

Improving the hygienic quality of forages for horse nutrition seems to be a reasonable target for decreasing the prevalence of pulmonary diseases. The aim of the experiment was to study the effects of different agricultural practices on the main aero-allergens contained in forages, including breathable dust, fungi, mycotoxins and pollens.

RESULTS

Results showed that the late harvest of hay, a second crop or a haylage production provides a good alternative to increase hygienic quality by reducing fungi contamination and breathable dust content. Barn drying of hay, while having no effect on breathable dust, similarly reduced fungi contamination. In contrast, when hay was harvested at a lower dry mass content (750 g DM kg⁻¹ versus 850 g DM kg⁻¹), both breathable dust and fungi contaminations were increased, which could at least be reversed by adding propionic acid just before baling. Zearalenone was detected in different hays, and even in one case, in breathable dust.

CONCLUSION

Overall, our data suggest that different approaches can be used to increase forage hygienic quality for horse feeding and thus reduce their exposure to factors involved in equine pulmonary disease.

Exposure assessment of mycotoxins in cow's milk in Argentina

A stochastic simulation model was developed to carry out the first quantitative risk exposure assessment of the mycotoxin level in cow's milk produced in Argentina. The prevalence and concentration of aflatoxin M1 (AFM1), deoxynivalenol (DON) and zearalenone (ZEA) were modeled at various stages through milk processes complying with Argentinean practices. Concentration of AFM1 (0.059ppb), DON (0.338ppb) and ZEA (0.125ppb) in dairy milk were estimated. The proportion of feed samples that exceeded the maximum level accepted by European regulations for AFB1, DON and ZEA were estimated at 25.07%, 0.0% and 8.9%, respectively. The percentage of milk samples that exceeded the maximum level accepted for AFB1 by the MERCOSUR (0.5ppb) and the European Union regulations (0.05ppb) were 0.81 and 32.65, respectively. The probability distribution of AFM1 concentration in milk was affected by the carry-over rate equations applied in the model. Mycotoxin levels in corn silage and concentrated feeds were the factors most correlated with mycotoxin concentrations in milk. Therefore, agricultural practices, crop management and feed production require prompt attention regarding mycotoxin issues.

Fungi isolated from olive ecosystems and screening of their potential biotechnological use

This study investigated the fungi diversity of fresh olive (Olea europaea L.) fruits, olive paste (crushed olives) and olive pomace (solid waste) and screened and quantified enzymatic activities with biotechnological applications. Fungi were randomly isolated from olive cultivars from Castilla La Mancha region (Spain). Identification included comparison of their polymerase chain reaction (PCR) amplicons of the ITS1-5.8S-ITS2 ribosomal DNA region, followed by nucleotide sequence analysis. Fourteen different species with DNA sequences of different similarities were identified, belonging to seven different genera (Aspergillus, Penicillium, Rhizomucor, Mucor, Rhizopus, Lichtheimia and Galactomyces). Aspergillus fumigatus, followed by Galactomyces geotrichum, Penicillium commune and Rhizomucor variabilis var. regularior were the most frequent species. Specific enzyme screening was assayed on agar plates, using cellobiose, carboxymethylcellulose (CMC), polygalacturonic acid and CaCl(2)/Tween 80 as substrates for β-glucosidase, carboxymethylcellulase (CMCase), polygalacturonase and lipase, respectively. Species exhibiting the best activities were: Aspergillus fumigatus (for β-glucosidase, CMCase and lipase); Rhizopus oryzae (for β-glucosidase and lipase); Rhizomucor variabilis (for β-glucosidase, CMCase and polygalacturonase); Mucor fragilis (β-glucosidase, CMCase and lipase); Galactomyces geotrichum (for β-glucosidase, polygalacturonase and lipase) and Penicillium commune and Penicillium crustosum (for lipase). The species that had shown the best enzymatic activities were grown on hemicellulose, cellulose and pectin and some activities were quantified (xylanase, cellulase, β-glucosidase and pectinase). An isolate of A. fumigatus and one of A. niger showed the best cellulase and xylanase activities, while no species presented good pectinase and β-glucosidase activities. The selected species with potential enzymatic activities could be used for future applications of industrial interest.

Characterization of cultivated fungi isolated from grape marc wastes through the use of amplified rDNA restriction analysis and sequencing

Microbial assessment of grape marc wastes, the residual solid by-product of the wine-industry, was performed by identifying phylogenetically the fungal culturable diversity in order to evaluate environmental and disposal safety issues and to discuss ecological considerations of applications on agricultural land. Fungal spores in grape marc were estimated to 4.7 x 10(6) per g dry weight. Fifty six fungal isolates were classified into eight operational taxonomic units (OTUs) following amplified ribosomal DNA restriction analysis (ARDRA) and colony morphology. Based on 18S rRNA gene and 5.8S rRNA gene-ITS sequencing, the isolates representing OTUs #1, #2, #3, and #4, which comprised 44.6%, 26.8%, 12.5%, and 5.3%, respectively, of the number of the total isolates, were identified as Aspergillus fumigatus, Bionectria ochroleuca, Haematonectria haematococca, and Trichosporon mycotoxinivorans. The isolates of OTU#5 demonstrated high phylogenetic affinity with Penicillium spp., while members of OTUs #6 and #7 were closer linked with Geotrichum candidum var. citri-aurantii and Mycocladus corymbifer, respectively (95.4 and 97.9% similarities in respect to their 5.8S rRNA gene-ITS sequences). The OTU#8 with a single isolate was related with Aspergillus strains. It appears that most of the fungal isolates are associated with the initial raw material. Despite the fact that some of the species identified may potentially act as pathogens, measures such as the avoidance of maintaining large and unprocessed quantities of grape marc wastes in premises without adequate aeration, together with its suitable biological treatment (e.g., composting) prior to any agriculture-related application, could eliminate any pertinent health risks.

Aspergillus fumigatus toxicity and gliotoxin levels in feedstuff for domestic animals and pets in Argentina

AIMS

To evaluate gliotoxin production by Aspergillus fumigatus strains isolated from feedstuff intended for domestic animals and pets, and to determine the amount of gliotoxin in these substrates.

METHODS AND RESULTS

A total of 150 feedstuff samples were collected. They were composed of 30 samples each of five different feed types (pigs, poultry, cattle, horse and pets). Aspergillus fumigatus gliotoxin production ability and gliotoxin presence in feedstuff was determined by HPLC. Aspergillus fumigatus strains were isolated from all of the tested samples. Strains from cattle, horses and pet food were able to produce gliotoxin. Corn silage samples intended for cattle did not show gliotoxin contamination. All the other tested samples had gliotoxin levels ranging from 29 to 209 microg g(-1). Horse and poultry feed samples had the greatest contamination frequency.

CONCLUSIONS

Feed samples contaminated with gliotoxin are potentially toxic to animals.

SIGNIFICANCE AND IMPACT OF THE STUDY

The presence of gliotoxin could affect animal productivity and health. Moreover, there are risks of contamination to farm workers handling improperly stored animal feed. Aspergillus fumigatus strains isolated from different sources should be investigated to determine prevention and control strategies.

A review of chemical, biological and fertility control options for the camel in Australia

Since their introduction to Australia in 1840 the one-humped camel, Camelus dromedarius, has gone from the colonist’s companion to a conservationist’s conundrum in the fragile arid ecosystems of Australia. Current management techniques are failing to curb present population growth and alternatives must be sought. This review assess the applicability of currently registered and developmental vertebrate pesticides and fertility control agents for camel control, as well as examining the potential usefulness of known C. dromedarius diseases for biological control. Not surprisingly, little is known about the lethality of most vertebrate pesticides used in Australia to camels. More has been published on adverse reactions to pharmaceuticals used in agriculture and the racing industry. An examination of the literature on C. dromedarius diseases, such as camel pox virus, contagious ecthyma and papillomatosis, indicates that the infections generally result in high morbidity but not necessarily mortality and this alone may not justify their consideration for use in Australia. The possibility exists that other undiscovered or unstudied biological control agents from other camilid species may offer greater potential for population control. As a long-lived species the camel is also not ideally suited to fertility control. Notwithstanding, anti-fertility agents may have their place in preventing the re-establishment of camel populations once they have been reduced through mechanical, biological or chemical means. Delivery of any generic chemical or fertility control agent will, however, require a species-tailored pathway and an appropriate large-scale deployment method. Accordingly, we put forward avenues of investigation to yield improved tools for camel control.

Gliotoxin natural incidence and toxigenicity of Aspergillus fumigatus isolated from corn silage and ready dairy cattle feed

Corn silage is an important feed source for dairy and beef cattle in central Argentina. The presence of thermophilic species Aspergillus fumigatus is among the major problem in silage, as many strains can produce several mycotoxins that affect the health of dairy cattle. The aims of the present study were to determine total fungal counts and relative density of A. fumigatus in silage samples, and to determine the natural incidence of gliotoxin in silage and ready dairy feed samples. The potential gliotoxin production of A. fumigatus isolated from silage was also recorded. A total of 90 samples were investigated, which were taken immediately after opening of the silo and the end of the ensiling period of about after 5 months. Sampling was performed manually through silos in transects at 3 levels per silo. Thirty samples of ready cattle feed (corn silage, ground corn, barley, cotton seed, brewer grains) were collected and investigated as well. Gliotoxin contamination was determined by HPLC. The ability of A. fumigatus to produce gliotoxin was measured using a TLC method. Results show that in all samples, the total number of yeasts and moulds exceeded 1×104 cfu/g. Aspergillus was the most prevalent genus followed by Fusarium and Penicillium spp. Investigations of the isolated A. fumigatus strains showed that many of these strains produced more than one mycotoxin. All samples showed gliotoxin contamination, but the strains isolated from ready cattle feed had higher gliotoxin levels than those isolated from corn silage. The gliotoxin concentrations found in this study exceeded the levels that are known to induce immunosuppressive and apoptotic effects in vitro. Although at present the oral bioavailability of gliotoxin in cattle is not known, the presented data suggest that its presence in feedstuffs could affect productivity and present a health risk for dairy cows.