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Detection and differentiation between mycotoxigenic and non-mycotoxigenic strains of two Fusarium spp. using volatile production profiles and hydrolytic enzymes

Keshri, G., Magan, N.
Journal of applied microbiology 2000 v.89 no.5 pp. 825-833
Fusarium verticillioides, beta-N-acetylhexosaminidase, beta-glucosidase, electronic nose, food industry, fungi, headspace analysis, lawns and turf, polymers, principal component analysis, spoilage, spores, toxigenic strains, volatile compounds, water activity
Volatile profiles and hydrolytic enzyme production by one non-mycotoxigenic and three mycotoxigenic strains of Fusarium moniliforme and F. proliferatum, grown in vitro for up to 96 h on a grain medium at 25 degrees C/0.95 water activity, were examined for differentiation of isolates. After spore lawn inoculation, measurements were made after 48, 72 and 96 h by sampling the head space above cultures with an electronic nose system using a 14 sensor surface polymer array, and by extraction and quantification of hydrolytic enzymes. There was good reproducibility of volatile patterns between replicates of the same treatment. Principal component analysis indicated that discrimination could be achieved between the uninoculated controls, the non-mycotoxigenic strain and the mycotoxin-producing strains for both species after 48 h. The total and specific activity of three out of seven enzymes (beta-D-glucosidase, alpha-D-galactosidase and N-acetyl-beta-D-glucosaminidase) were found to increase significantly in the non-mycotoxigenic when compared with the toxigenic strains of both species after 72 h. Activities of the others (beta-D-fucosidase, alpha-D-mannosidase, beta-D-xylosidase and N-acetyl-alpha-D-glucosaminidase) were not significantly different between strains. The study has shown for the first time that it is possible to differentiate between mycotoxigenic and non-mycotoxigenic strains of such spoilage fungi based on their volatile production patterns using an electronic nose system. These results have significance in the development of methods for the early detection of toxin-producing spoilage moulds in the food industry.