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TDK conference 2013

Nitrate contents of higher edible mushrooms
Bóbics Renáta - year 4
SzIU, Faculty of Veterinary Science, Department of Botany
Supervisor: Vetter János dr.


Nitrates as ionic, soluble useful nitrogen sources are not only important components (factors) in the biological nitrogen cycle, but have a well known toxicological role for animals and humans (nitrate-nitrite poisoning: methaemoglobinemia). Important basis of data is available on nitrate level of waters, soils, on uptake of plants and on their occasional accumulation, on NO3 metabolism and on poisoning of animals and humans, including the ecotoxicological relations. Practically we do not have data on nitrate level of higher mushrooms and on its regulating factors especially.

Aim of recent investigation was to produce primary data on nitrate level of frequent edible mushroom species especially because food chemical, toxicological or mycological data were not published. Objects of our study were obtained from the sample collection of botanical department (Faculty of Veterinary Science, Szent István University). Nitrate contents were determined with a spectrophotometric method from the water extract (after a deproteinization), the data were given in mg NO3/kg dm.

Data of investigations were grouped and estimated from different aspects. The main conclusions:

1. Seven taxa of saprotrophic wild growing species had remarkable average nitrate level ( Clitocybe nebularis (6983 mg/kg dm.),Clitocybe odora (1766 mg/kg dm.), Lepista nuda (5844 mg/kg dm.), L. irina (7238 mg/kg dm.), L. personata (5558 mg/kg dm.), Macrolepiota rachodes (1877 mg/kg sza.) and slightly Macrolepiota procera (627 mg/kg dm.). Although the samples were originating from different habitats and different years their accumulating character for nitrates seems to be doubtless. The other examined saprotrophic species had only 2-300 mg/kg nitrate contents.

2. Average nitrate content of mycorrhizal species is 219 mg/kg dm., which is similar to average of mushroom group No. 1 without extreme values. The estimated concentrations were between 150 and 450 mg/kg dm.

3. Nitrate level of wood destroying fungi (n=24) had essentially identical with the former group but the measured concentrations were in more restricted interval.

4. Cultivated mushroom samples (different varieties of eight species) (n=26) had higher average NO3 content (333,6 mg/kg dm.) than the samples from former groups but significant majority of samples had a nitrate level under 250 mg/kg dm.

The demonstrated groups of analytical data had verified the low nitrate character of the frequent edible higher mushrooms but seven saprotrophic taxa simultaneously had higher or remarkable higher nitrate level (which can be defined as accumulation). The mycological and other reasons of these are unknown, further investigations and data are required for the discussion. The nitrate accumulation is doubtless and it is seems to be depend from the systematic taxa.

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