Rapid determination of food grain infection by fungi Fusarium and their species detection (part 1)
AbstractCurrently contamination of food grains with Fusarium spp. is determined by conventional mycological methods and can last up to 30–40 days. The method specificity is highly dependent on the subjective evaluation of the researchers. The alternative to traditional mycological methods is detection by PCR. The purpose of the study was to improve the contamination analysis method of food grains infected by Fusarium for analysis time reducing and species detection specificity increasing. Investigations were carried out on food grains samples harvested in 2009–2011 from 5 federal regions of Russia. On the first stage, 100 grains were sowing on potato-sucrose medium and then incubated at 24 °C for 7–10 days. At the second stage, the Fusarium species composition grown from food grains was estimated by two methods. The first method was mycological for monospore isolates. The second one was PCR analysis of DNA extracts from the combined sample of Fusarium mycelium which grew on a foodgrains sample. Species-specific primers of such mycotoxins producers as F. graminearum, F. culmorum, F. sporotrchiodes, F. langsethiae, F. poae, F. avenaceum, F. tricinctum were used for PCR detection. The species composition of viable Fusarium spp. fungi revealed in foodgrains samples by mycological method completely concided with the results of PCR analysis. In result, the method that combines traditional mycological sowing for detection of viable species with PCR species detection of the mycelium in integrated sample has been developed. The method significantly reduces test duration (3–4 times) by excluding the sieving step in obtaining monospore fungi isolates for further species identification. The method also allows obtaining reliable data on the viable Fusarium speсies including producers of toxins in foodgrains. Thus, the idea of improving of the identification stage allowing reducing labor costs and increasing of the method specificity was realized.
Keywords:Fusarium spp., rapid detection of mycotoxigenic molds, real-time PCR, food grains, infection of food grains by Fusarium spp, species detection Fusarium