Mycoflora of paddy and milled rice produced in the region of Northeastern Argentina and Southern Paraguay

Abstract

Thirty samples of paddy rice and twenty-five of milled rice were obtained from processing centers located in two northern Provinces of Argentina and one southern Province of Paraguay. Contaminating fungi were enumerated by direct plating on dichloran rose bengal chloramphenicol agar and oxytetracycline glucose yeast extract agar before and after surface disinfection. All fungi were isolated and identified to the genus level and percentage infection of samples calculated. Those belonging to the genera Penicillium, Aspergillus and Fusarium were identified to species level. The surface mycoflora was dominated by storage fungi, notably Penicillium citrinum (73% of samples), P. islandicum (60% of samples), Aspergillus niger, A. flavus and Fusarium semitectum. The major fungi found as internal contaminants of paddy rice were, again, Penicillium citrinum (66% of samples) and P. islandicum (50% of samples). Milled rice showed a lower level of contamination, but with a similar species distribution, Penicillium citrinum and P. islandicum again being the main contaminants. The presence of these species suggests a potential for mycotoxin production. Further studies are needed to establish the mycotoxin quality of rice from this region.