Growth characterization and predictive behavior of Eurotium species in a feedstuff matrix / Caracterización del crecimiento y comportamiento predictivo de especies de Eurotium en matriz de alimento balanceado

ABSTRACT Animal feeds are characterized by low water activity values. Nevertheless, fungal contamination withEurotiumspecies are quite common, causing nutritional depletion, spoilage and economic losses. The aim of this work was to assessEurotiumamstelodami,E. chevalieri,E. repensandE. rubrumgrowth in a feed matrix at different conditions of water activity (0.71-0.97) and temperature (5, 15, 25, 30 and 37°C). It was found thatEurotiumspecies are able to grow in a wide range of water activity and temperature in a short period of time (7 days) and faster than in synthetic media. Rosso and probabilistic models were applied in order to determine the limiting and optimum growth conditions as well as growth probability at certain combinations of environmental factors. Both models provided an accurate fit to the cardinal parameters and good performance for growth/no growth cases. This is the first report assessing the growth parameters ofEurotiumspecies directly in animal feed. Data obtained in the present study is useful to predict and avoidEurotiumspecies growth in animal feed.

RESUMEN Los alimentos balanceados se caracterizan por tener bajos valores de actividad de agua. Sin embargo, la contaminación por hongos con especies deEurotiumes bastante común y causa agotamiento nutricional, deterioro y pérdidas económicas. El objetivo de este trabajo fue evaluar el crecimiento deEurotiumamstelodami,E. chevalieri,E. repensyE. rubrumen una matriz de alimento balanceado a diferentes condiciones de actividad de agua (0,71-0,97) y temperatura (5, 15, 25, 30 y 37°C). Se determinó que las especies deEurotiumpueden crecer en un amplio rango de actividades de agua y temperatura en un corto período de tiempo (7 días), y a mayor velocidad que en medio sintético. Se utilizaron los modelos de Rosso y probabilísticos para determinar las condiciones de crecimiento limitantes y óptimas, así como la probabilidad de crecimiento en ciertas combinaciones de factores ambientales. Ambos modelos proporcionaron un ajuste preciso a los parámetros cardinales y una buenaperformancepara los casos de crecimiento/sin crecimiento. Este es el primer trabajo que evalúa los parámetros de crecimiento de las especies deEurotiumdirectamente en alimento balanceado. Los datos obtenidos en el presente estudio son útiles para predecir y evitar el crecimiento de especies deEurotiumen este tipo de alimentos.

Growth characterization and predictive behavior of Eurotium species in a feedstuff matrix.

Animal feeds are characterized by low water activity values. Nevertheless, fungal contamination with Eurotium species are quite common, causing nutritional depletion, spoilage and economic losses. The aim of this work was to assess Eurotium amstelodami, E. chevalieri, E. repens and E. rubrum growth in a feed matrix at different conditions of water activity (0.71-0.97) and temperature (5, 15, 25, 30 and 37°C). It was found that Eurotium species are able to grow in a wide range of water activity and temperature in a short period of time (7 days) and faster than in synthetic media. Rosso and probabilistic models were applied in order to determine the limiting and optimum growth conditions as well as growth probability at certain combinations of environmental factors. Both models provided an accurate fit to the cardinal parameters and good performance for growth/no growth cases. This is the first report assessing the growth parameters of Eurotium species directly in animal feed. Data obtained in the present study is useful to predict and avoid Eurotium species growth in animal feed.

Diversity and abundance of airborne fungal spores in a rural cold dry desert environment in Argentinean Patagonia.

This work describes a longitudinal study of three consecutive years carried out in the air of agricultural environments located in Northern Patagonia with cold dry desert climate (Köppen: Bwk). This study area comprises a rural valley with unique geographical and climatological conditions. Therefore, the aim of this work is to quantify and determine its fungal diversity, so this knowledge will contribute to detect potential pathogenic and toxic fungi that has been adapted to this type of environment and may overcome the incipient climate change. Samplings were conducted in two geographical zones of the study area and a microflow air sampler was used to isolate fungal taxa. The annual mean fungal counts were found in the order of E+03 CFU/m3 of air. The aerial mycoflora revealed a wide biodiversity of at least 28 genera and 50 fungal species. Cladosporium was the most abundant genus (76.97%), followed by Alternaria (12.48%), Epicoccum (4.41%) and Botrytis (1.81%). The rest of the genera were found in relative densities lower than 1%. In terms of species, C. cladosporioides (34.82%), C. limoniforme (21.72%), A. tenuissima (10.94%) and C. asperulatum predominated (9.01%). This is the first report of the air mycoflora of rural environments with cold dry desert climate which provides useful information to take preventive measures to avoid biological damage.

Effect of water activity and temperature on the growth of Eurotium species isolated from animal feeds / Efecto de la actividad del agua y la temperatura en el crecimiento de especies de Eurotium aisladas de alimentos para animales

Background. Xerophilic fungi represent a serious problem due to their ability to grow at low water activities causing the spoiling of low and intermediate moisture foods, stored goods and animal feeds, with the consequent economic losses. Aims. The combined effect of water activity and temperature of four Eurotium species isolated from animal feeds was investigated. Methods. Eurotium amstelodami, Eurotium chevalieri, Eurotium repens and Eurotium rubrum were grown at 5, 15, 25, 37 and 45°C on malt extract agar adjusted with glycerol in the range 0.710-0.993 of water activities. Results. The cardinal model proposed by Rosso and Robinson (2001) was applied to fit growth data, with the variable water activity at fixed temperatures, obtaining three cardinal water activities (awmin, awmax, awopt) and the specific growth rate at the optimum aw (μopt). A probabilistic model was also applied to define the interface between growth and no-growth. The cardinal model provided an adequate estimation of the optimal aw to grow and the maximum growth rate. The probabilistic model showed a good performance to fit growth/no-growth cases in the predicted range. Conclusions. The results presented here could be applied to predict Eurotium species growth in animal feeds (AU)

Antecedentes. Los hongos xerófilos son un problema importante debido a su capacidad de crecer a bajas actividades del agua, lo que causa el deterioro de alimentos a humedades bajas e intermedias, de materias primas almacenadas y de piensos para animales, con las consecuentes pérdidas económicas. Objetivos. Se llevó a cabo un estudio sobre el efecto de los factores ambientales (temperatura y actividad del agua) sobre el crecimiento de cuatro especies pertenecientes al género Eurotium aisladas de piensos para animales. Métodos. Se estudió el crecimiento de Eurotium amstelodami, Eurotium chevalieri, Eurotium repens y Eurotium rubrum a valores de actividad de agua en el rango 0,710-0,993 en el medio de cultivo agar extracto de malta modificado con glicerol, y valores de temperatura de 5, 15, 25, 37 y 45°C. Resultados. El modelo cardinal propuesto por Rosso y Robinson (2001) se aplicó para realizar el ajuste de datos con la actividad del agua como variable a una temperatura fija; se obtuvieron tres valores cardinales de actividad del agua (awmin, awmax, awopt) y la tasa de crecimiento específico en el valor óptimo de aw (μopt). También se aplicó un modelo probabilístico para definir la interfase entre crecimiento y no crecimiento. El modelo cardinal presentó una adecuada estimación del awopt y la máxima velocidad de crecimiento. El modelo probabilístico fue adecuado para el ajuste de los casos de crecimiento/falta de crecimiento en el rango previsto. Conclusiones. Los resultados presentados en este artículo pueden aplicarse para pronosticar el crecimiento de especies de Eurotium en piensos para animales (AU)

Effect of water activity and temperature on the growth of Eurotium species isolated from animal feeds.

BACKGROUND: Xerophilic fungi represent a serious problem due to their ability to grow at low water activities causing the spoiling of low and intermediate moisture foods, stored goods and animal feeds, with the consequent economic losses. AIMS: The combined effect of water activity and temperature of four Eurotium species isolated from animal feeds was investigated. METHODS: Eurotium amstelodami, Eurotium chevalieri, Eurotium repens and Eurotium rubrum were grown at 5, 15, 25, 37 and 45°C on malt extract agar adjusted with glycerol in the range 0.710-0.993 of water activities. RESULTS: The cardinal model proposed by Rosso and Robinson (2001) was applied to fit growth data, with the variable water activity at fixed temperatures, obtaining three cardinal water activities (awmin, awmax, awopt) and the specific growth rate at the optimum aw (µopt). A probabilistic model was also applied to define the interface between growth and no-growth. The cardinal model provided an adequate estimation of the optimal aw to grow and the maximum growth rate. The probabilistic model showed a good performance to fit growth/no-growth cases in the predicted range. CONCLUSIONS: The results presented here could be applied to predict Eurotium species growth in animal feeds.

Mycotoxigenic fungi and natural co-occurrence of mycotoxins in rainbow trout (Oncorhynchus mykiss) feeds.

Samples of rainbow trout feed were analyzed with the aim to determine the mycobiota composition and the co-occurrence of mycotoxins. A total of 28 samples of finished rainbow trout feed from hatcheries in the provinces of Río Negro and Neuquén, Argentina, were studied. Fungal counts were obtained on three culture media in the ranges of <10 to 4.2 × 104 CFU/g on Dichloran Rose Bengal Chloramphenicol Agar (DRBC), <10 to 5.1 × 104 CFU/g on Dichloran Chloramphenicol Peptone Agar (DCPA) and <10 to 3.6 × 104 CFU/g on Dichloran 18% Glycerol Agar (DG18). The most frequent mycotoxigenic fungi were Eurotium (frequency (Fr) 25.0%), followed by Penicillium (Fr 21.4%) and Aspergillus (Fr 3.6%). The most prevalent mycotoxigenic species were E. repens (Fr 21.4%) and E. rubrum (Fr 14.3%). All samples were contaminated with mycotoxins: 64% samples were contaminated with T-2 toxin (median 70.08 ppb), 50% samples with zearalenone (median 87.97 ppb) and aflatoxins (median 2.82 ppb), 25% with ochratoxin A (median 5.26 ppb) and 3.57% samples with deoxynivalenol (median 230 ppb). Eight samples had a fumonisins contamination level below the limit of detection. Co-occurrence of six mycotoxins was determined in 7% of the samples.

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs.

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

Mycotoxins and mycotoxigenic fungi in poultry feed for food-producing animals.

Moulds are capable of reducing the nutritional value of feedstuff as well as elaborating several mycotoxins. Mycotoxin-contaminated feed has adverse effects on animal health and productivity. Also, mycotoxins may be carried over into meat and eggs when poultry are fed with contaminated feed. In a point prevalence study feedstuff used for poultry nutrition in Argentina was analyzed for fungal flora, natural incidence of selected mycotoxins, and nutritional quality. Ten mould genera were recovered, six of them known to be mycotoxigenic. More than 28 species were determined. Fumonisins were detected in all the samples (median 1,750 ppb). Forty-four out of 49 samples (90%) were contaminated with DON (median 222 ppb) and OTA (median 5 ppb). Also, 44 out of 49 samples were contaminated with aflatoxins (median 2.685 ppb), 42 samples (86%) with ZEA (median 50 ppb), and 38 samples (78%) with T2-toxin (median 50 ppb). Ninety percent of the samples had at least one type of nutritional deficiency. This study indicates the need for continuous assessment of the mycological status of animal feed production, in order to feed animals for optimal performance ensuring food safety.

Mycoflora and natural incidence of selected mycotoxins in rabbit and Chinchilla feeds.

Mycotoxins are secondary metabolites produced by filamentous fungi that cause a toxic response when ingested by animals or man. Demand of natural fur, such as those from rabbit and chinchilla, produced under controlled conditions, has increased worldwide. The toxicogenic mycoflora contaminating feeds for these animals was enumerated and identified. Six of the major mycotoxins implicated in animal mycotoxicosis were detected and quantified. Moulds count ranged from <10 to 4.7 × 10(5) CFU g(-1); 14% of the samples exceeded the limit that determines hygienic feed quality. More than twenty species belonging to the five most important mycotoxigenic mould genera were recovered. Among the analyzed mycotoxins, aflatoxins were recovered in 100% of the examined samples, deoxynivalenol in 95%, fumonisins in 100%, ochratoxin A in 98%, T2 toxin in 98%, and zearalenone in 100%. Cooccurrence of mycotoxins was observed in 100% of the samples analyzed. Exposure to multiple mycotoxins was thus demonstrated for these animals.