Alternaria metabolites in sunflower seeds

Production of alternarioi and alternariol monomethyl ether in natural substrates in comparison with semisynthetic culture medium

The comparison In toxins production and growth byAlternarla strains in liquid, solid culture media and natural substrates (rice and sunflower) was evaluated. Ground rice- corn steep liquor medium (GRCS) was the more suitable medium for production of alternariol (AOH) and alternariol monomethyl ether(AME). The maximum levels produced were 676 μg/50ml AOH and 1570/50ml AME. Rice was better than sunflower In supporting toxins production. Different ratios AOH/AME were found according to the substrate evaluated.

Mycoflora and occurrence of alternariol and alternariol monomethyl ether in Brazilian sunflower from sowing to harvest

The present study aimed to analyze the mycoflora and the occurrence of alternariol (AOH) and alternariol monomethyl ether (AME) in grain samples of sunflower during different stages of plant development in Nova Odessa, State of São Paulo, Brazil. The data obtained were correlated with the presence of fungi in soil, wind-dispersed fungi, and the predominant climatic conditions of the region where the experiment was carried out. Analysis of the mycoflora revealed the presence of Fusarium verticillioides and Alternaria alternata in 70% and 46% of the samples, respectively. The profile of wind-dispersed fungi also showed F. verticillioides as the most frequently isolated fungus (68%), although A. alternata was detected in 28% of samples. In soil, Penicillium was the most frequent species (49.9%), followed by F. verticillioides (47.7%) and A. alternata (10.9%). Regarding water activity, sunflower grains presenting a high frequency of isolation of F. verticillioides and A. alternatahad a water activity ranging from 0.92 to 0.96, and statistical analysis revealed a negative linear correlation between the isolation of fungi and water activity. HPLC analysis showed that 18% of the sunflower grains were contaminated with alternariol (24.9-170.9 ng/g) and 10% with alternariol monomethyl ether (14.1-108.6 ng/g). The contamination of sunflower grains with AOH and AME in the field was low when compared to the LD50 necessary to cause toxicity to animals. However, the contamination with other toxigenic fungi such as F. verticillioides may indicate the presence of other mycotoxins in sunflower grains and a possible synergistic effect between them. This is the first report of the natural occurrence of alternariol and alternariol monomethyl ether in sunflower grains in Brazil.

Mycotoxin production byAlternaria strains isolated from tomatoes affected by Blackmold in Argentina

A survey on 28 samples of Blackmold" affected tomatoes cultivated in Argentina was made.A. alternata was the most frequently occurring species.A. tenuissima, A. longipes yUdocladium spp. were also isolated. All theAlternaria strains (25) were able to produce mycotoxins, including Alternariol, Alternariol Monomethyl Ether and Tenuazonic Acid, on autoclaved rice (at 25°C and 8°C) and in fresh surface disinfected tomatoes at 25°C.

Pine nuts: the mycobiota and potential mycotoxins

The mycobiota of pine nuts was investigated. In total, 1832 fungi belonging to 31 species and 15 genera (Ascomycota, 2; Zygomycota, 3; mitosporic fungi, 10) could be isolated. Cladosporium spp. dominated the mycobiota with 685 isolations followed by Phoma macrostoma with 351 isolations. Overall, 16 potentially mycotoxigenic species were present on pine nuts.Key words: pine nuts, mycobiota, potential mycotoxins.

Effects of food preservatives on Alternaria alternata growth and tenuazonic acid production

The effects of different organic acids on Alternaria alternata growth and tenuazonic acid production (TeA) were evaluated. Both TeA pure toxin solution and TeA production in solid medium were considered. Sodium benzoate, potassium sorbate and sodium propionate, all preservatives commonly used by food industry in Argentina, were tested. TeA was stable as pure toxin solution when was treated with the salts of organic acids used. A differential effect was observed when the preservatives were evaluated in relation to A. alternata growth and TeA production in solid medium. Levels above 10 mg/kg of sodium benzoate and potassium sorbate produced a total inhibition of fungal development and toxin biosynthesis. Sodium propionate produced a 59% decrease in A. alternata growth and total inhibition of TeA production only at the highest concentration of preservatives used.

Production of alternariol and alternariol mono-methyl ether by isolates of Alternaria spp. from Argentinian maize

Alternaria cultures (87 isolates of Alternaria alternata, four of A. tenuissima, two of A. radicina, and three of Alternaria state of Pleospora infectoria respectively, from maize) were screened to determine their ability to produce alternariol (AOH) and alternariol monomethyl ether (AME) on maize and rice. Only 28 A. alternata stains had toxigenic capacity. When maize was used as substrate 21 of 28 isolates produced AOH and AME, and 23 of 28 strains produced AOH and 22 of 28 produced AME when rice was used. The level of AOH produced by the isolates ranged from 0.3 to 2.1 mg/kg on maize and from 0.4 to 9.9 mg/kg on rice. The AME production by the stains ranged between 0.3 and 3.3 mg/kg both on maize and on rice. These results could indicate a low probability of AOH and AME occurring naturally on maize in Argentina.

Mycotoxins in ingredients of animal feeding stuffs: I. Determination of Alternaria mycotoxins in oilseed rape meal and sunflower seed meal

A multi-toxin method was developed for the detection of some of the known Alternaria mycotoxins, altenuene, iso-altenuene, alternariol, alternariol monomethyl ether, tenuazonic acid and altertoxin I in oilseed rape meal and sunflower seed meal. The method involves extraction of the toxins with an acidified mixture of acetonitrile: aqueous potassium chloride solution, followed by liquid-liquid extraction and further purification using gel permeation chromatography. The final extract is then examined on a reverse phase high performance liquid chromatographic gradient system with both fluorescence and UV detection. The average recoveries found were 94, 84, 109, 85, 66 and 93% for spiked oilseed rape meal samples and 91, 89, 96, 75, 61 and 102% for spiked sunflower meal samples with limits of determination of about 40, 50, 50, 40, 350 and 200 micrograms/kg for the above toxins, respectively. Detection limits were about 30% of these values. Thirty samples of oilseed rape meal and 22 samples of sunflower meal were examined using the methods developed. Twenty of the oilseed rape products which had been grown in the UK were free from contamination while 10 contained one or more of tenuazonic acid, alternariol and alternariol monomethyl ether. In contrast, all of the sunflower meal samples, of Argentinean, Indian or EC origin, were contaminated with one or more of alternariol, alternariol monomethyl ether and tenuazonic acid. Average levels of alternariol, alternariol monomethyl ether and tenuazonic acid were 68, 55 and 730 micrograms/kg, respectively for the contaminated samples of oilseed rape meal and 180, 100 and 1900 micrograms/kg, respectively for the contaminated samples of sunflower seed meal.

Effect of dichlorvos on growth and mycotoxin production by Alternaria alternata

The effect of dichlorvos (DDPV) on growth and alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) production was evaluated both in culture media and on sunflower seeds. At the levels evaluated of 1 to 600 mg/kg, the insecticide showed a slight effect on the linear growth rate, which was dose dependent, and caused morphological changes in the mycelia and conidia. The pesticide had a remarkable influence on AOH, AME and TA production.

Mycotoxin production by Alternaria alternata strains isolated from red delicious apples in Argentina

Eleven Alternaria alternata strains isolated from Red Delicious apples in cold storage in Argentina, were tested for alternariol and alternariol methyl ether production in laboratory media and in whole fresh fruits. Most of them were able to produce both toxins in all media. They were detected also in mycelium free filtrates from liquid cultures and in asymptomatic tissues from inoculated fruit. Thus, in the evaluation of mouldy core incidence in apples, the presence of A. alternata toxins in tissues should be considered even in the absence of mycelia.