E. Coli

A. Krikðtaponis, J. Stakënienë, A. Lugauskas

Toxigenic fungi in human environment
A. Krikðtaponis, J. Stakënienë, A. Lugauskas
Institute of Botany, Þaliøjø eþerø 49, LT-2021 Vilnius, Lithuania
Fungal species compositions on vegetable-born food products and in the air and dust of dwellings were studied in 1996–2000. Seven food selling-storage places and 14 residences were investigated, 179samples of 94 names of food products as well as 50 air and 118 dust samples were surveyed. Ability of 393 fungal isolates to produce secondary metabolites grown on Czapek – yeast extract and yeast extract – sucrose agar media was tested, 124 strains were regarded as active producers of secondary metabolites. Key words: microscopic fungi, mycotoxins, food, living environment

INTRODUCTION Adequatenutrition and clean environment are the basic factors predetermining the quality of human life. Healthy food ought to be biologically valuable, free of chemical pollution and microbiological contamination. Taking into consideration the fact that activities of people are concentrated indoors, microbiological pollution of the premises directly influences the state of health of the occupants. One ofthe hazards associated with fungi is their ability to produce toxic secondary metabolites – mycotoxins which present a group of heterogeneous organic compounds hazardous for living organisms, including humans. Arising with dust, fungal spores can be inhaled, mycotoxins easily diffuse, penetrate the alveoli and get into the blood. Consequently, the risk of inhalable mycotoxicoses arises [1, 2].Food polluted by mycotoxins can cause alimentary toxicoses, moreover, mycotoxins may be carcinogenic, nephrotoxic, hepatoxic, haemorrhagic, oestrogenic or cause inflammatory effects. According to the literature, the most common producers of mycotoxins are fungi from the genera Aspergillus, Penicillium, Fusarium [3]. The aim of the study was to determine the species of toxigenic fungi most common onfood and in living premises, and to evaluate their abilities to produce secondary metabolites. MATERIALS AND METHODS The study was performed in 1996–2000. In order to detect food-deteriorating fungi, specimens of fruit, vegetables, and other vegetable-born food products were collected from 7 food selling-storage places at a different time of the year. 179 samples of 94 above-mentioned products,grown and made in LithuaISSN 1392–0146. B i o l o g i j a . 2001. Nr. 4

nia or brought from other countries were investigated. Isolation of fungi was performed according to the methods described by R. A. Samson et al., 1992 [4]. The plating method was used when a specimen was evidently damaged by one fungal species, and the diluting was applied when several fungal species were suspected [4, 5].For the presence of toxigenic fungi in living environment, 14 residences considered as mould-problematic were surveyed; 50 air and 118 dust samples were investigated. A Krotov 818 slit-to-agar single stage impactor (cut-off 0.5 µm) was used for sampling total airborne propagules, simultaneously the settle plate method for direct airborne fungi isolation was applied. Dust samples were taken bysterile swabs and placed directly onto agar. Standard solid malt extract, corn extract, Czapek and Sabouraud dextrose media were used for fungi isolation and cultivation [6]. The ability of the isolated fungi to produce secondary metabolites (some of them could be toxic) was tested according to J. C. Frisvad et al. (1988) – the pure cultures were grown on secondary metabolism-stimulating CYA (Czapekyeast extract agar), YES (yeast extract-sucrose agar), and standard Czapek agar as a control [7]. Obvious changes of typical colours of developing fungal colonies as well as pigmentation of medium were registered. RESULTS AND DISCUSSION From food specimens, 288 fungal species ascribed to 93 genera and from the living environments 274 species belonging to 85 genera were isolated and identified. The...