| Abstract: | A duplex PCR method was developed for Z. mobilis species detection. Two sets of primers were used; the first one targeted a 530 bp region of the 23S rRNA gene, the amplified fragment corresponding to an internal control, while the second targeted a 900 bp region spanning the 16S and 23S rRNA gene regions and was Z. mobilis specific. This second primer pair was designed by comparison with corresponding sequences of a Sphingomonas sp., a bacterium that is phylogenetically the closest to Z. mobilis, and Gluconobacter oxydans that is taxonomically the closest relative found in cider. Results showed that the method was able to specifically amplify the two targets in all studied strains of Z. mobilis while only one fragment, corresponding to the internal control, was amplified for G. oxydans and the tested lactic acid bacteria commonly found in cider. The method threshold was determined by contaminating cider samples containing natural yeast and lactic acid bacteria flora. Within a 24 h period, ciders containing 102 CFU/mL of Zymomonas were detected as positives. The rapidity and reliability of this duplex PCR for detection of Z. mobilis directly from cider will certainly prove to be useful in detecting, early on during the fermentation phase, the presence of this spoilage microorganism. It will also be of interest as a complementary test when using the HACCP approach in the cider and beer industries. |
