Comparison of rose-bengal chloramphenicol agar and dichloran glycerol agar (DG18) for enumeration and ısolation of moulds from raisins

Abstract

Two different selective media as Rose-Bengal Chloramphenicol (RBC) Agar and Dichloran Glycerol (DG18) Agar were used for isolation and enumeration of molds from raisin, which is the main economic crop in Turkey and somewhere else. A total of 129 raisin samples were collected randomly during 1998-2000, of 94 were taken from several field vineyards and 35 from two different raisin packaging houses. Although after microbiological examinations no significant differences were found in relation with their fungal count (p>0,05), there was a marked variation (p<0.05) in terms of fungal diversity between the two media. Thus 53 species belonging six genera were obtained with DG 18 agar, whereas 74 species from 12 genera with RBC agar. There were 39 species common in the two media. The results warrant the need to use two selective media with different moisture or water activity in order to isolate and/or enumerate a more representative mycoflora including toxigenic and/or pathogenic from raisins.

Two different selective media as Rose-Bengal Chloramphenicol (RBC) Agar and Dichloran Glycerol (DG18) Agar were used for isolation and enumeration of molds from raisin, which is the main economic crop in Turkey and somewhere else. A total of 129 raisin samples were collected randomly during 1998-2000, of 94 were taken from several field vineyards and 35 from two different raisin packaging houses. Although after microbiological examinations no significant differences were found in relation with their fungal count (p>0,05), there was a marked variation (p<0.05) in terms of fungal diversity between the two media. Thus 53 species belonging six genera were obtained with DG 18 agar, whereas 74 species from 12 genera with RBC agar. There were 39 species common in the two media. The results warrant the need to use two selective media with different moisture or water activity in order to isolate and/or enumerate a more representative mycoflora including toxigenic and/or pathogenic from raisins.