From field to process: How storage selects toxigenic Alternaria spp. causing mouldy core in Red Delicious apples.

Apple is a major crop in Argentina where 50% of the production is derived to by-products. Industries process either recently harvested apples or fruit stored for up to 9 months. This crop is susceptible to fungal diseases both external and internal, such as mouldy core (MC). The incidence of fungal pathogens changes during storage, as well as the risk associated with their presence since some contaminants belong to mycotoxigenic genera. The objective of this study was to characterize the fungal contaminants of Red Delicious apple fruit in Argentina evaluating their evolvement from field to process, with main interest on MC causal agents and mycotoxigenic species. A total of 240 apples were analysed; 140, recently harvested and intended for fresh consumption (C), and 100 stored for 9 months in a refrigerated chamber (0-3 °C) and destined to industrialization (I). The 86% of fresh consumption apples showed external fungal lesions, and only 14% were undamaged; MC incidence was 34%. High biodiversity was observed; Penicillium was the predominant genus (54%), followed by Alternaria spp. (41%). Only 3% of industrialization fruit were undamaged, 48% had external lesions and 51% MC. However, biodiversity was lower in these apples. Alternaria spp. was recovered from 60% of apples, mainly causing MC, while Penicillium spp. took second place (34%). All the Alternaria isolates belonged to Section Alternaria with A. tenuissima as the predominant species-group. Alternariol was synthesised by 75% of the isolates, while both alternariol monomethyl-ether and tenuazonic acid by 76%. From the 100 I apples, 93 were contaminated with at least one of these mycotoxins. Alternaria was the main causal agent of MC in Argentinean Red Delicious apples, and fruit affected by this disease might be incorporated into the process line, with a consequent risk of mycotoxin contamination in apple by-products.

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.

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.