Jean-Christophe Meile

Differentiation and quantification of the ochratoxin: A producers Aspergillus ochraceus and Aspergillus westerdijkiae using PCR-DGGE

Ochratoxin A (OTA) is a nephrotoxic, teratogenic, immunotoxic, and carcinogenic mycotoxin which is produced in tropical zones mainly by Aspergillus carbonarius, A. niger, A. ochraceus, and A. westerdijkiae. A. ochraceus and A. westerdijkiae species are phenotypically and genomically very close but A. westerdijkiae produce OTA at a very higher level than A. ochraceus. These species have been differentiated recently. The DNA primer pairs which were drawn so far are not specific and a genomic region of the same size is amplified for both species or they are too specific, and in this case, the DNA of a single species is amplified. To help preventing OTA contamination of foodstuffs, the PCR‐DGGE (Denaturing Gradient Gel Electrophoresis) method was used to discriminate between A. ochraceus and A. westerdijkiae DNA fragments of the same size but with different sequences and thus faster access to a diagnosis of the toxigenic potential of the fungal microflora. The proposed methodology was able to differentiate A. westerdijkiae from A. ochraceus with only one primer pairs in a single run. A calibration based on initial DNA content was obtained from image analysis of the DGGE gels and a method of quantification of the two strains was proposed.

New traceability strategies based on a biological Bar Code by PCR-DGGE using bacterial and yeast communities for determining farming type of peach

Abstract Introduction: EU Regulations continue to be strict in order to allow the highest degree of insurance in foodstuffs’ safety and quality. The traceability and labeling of imported products in EU still remain a valuable issue (EU-Regulation 178/2002). One of the most important concerns of the customers is the product traceability, which is defined as the ability to screen the whole history or geographical origin or farming type of any food by certified methodologies. In this regard, we proposed to study the link between microbial ecology and farming type of foodstuffs via a unique molecular analytical technique which is followed by an image analysis. Purpose: A unique molecular analytical tool using 16S rDNA and 26S rDNA profiles generated by “PCR-DGGE” was used to detect the variation in bacterial and yeast communities respectively of peaches from Jordan (control fruit, organic farming and conventional farming). Results: When the 16S and 26S rDNA profiles were analyzed using image and multivariate analysis, certain microbiota were detected on peach fruits originating from Jordan. The resulted band profiles of bacteria and yeasts from different farming types were specific and could be used as a bar-code to discriminate the fruits’ farming type. Significance of the paper: This method could be considered as a new traceability technique which provides fruits with a unique biological bar-code and permits the possibility to control the farming type of foodstuffs.