Sugar-Rich Foods Carry Osmotolerant Yeasts with Intracellular and spp.

BACKGROUND Sugar-rich foods are of the main components of daily human meals. These foods with high sugar and low water content kill bacteria. However, osmotolerant yeasts survive and multiply. The aim of this study was to examine the occurrence of intracellular and spp. in yeast isolates from sugar-rich foods. METHODS Thirty-two yeast isolates from fresh fruits, dried fruits, commercial foods, and miscellaneous foods were identified by the sequencing of amplified products of 26S rDNA. Fluorescence microscopy and LIVE/DEAD bacterial viability kit were used to examine the occurrence of live bacteria inside the yeast's vacuole. Immunofluorescence assay was used to confirm the identity of intracellular bacteria as and . Polymerase chain reaction (PCR) was used for the detection of 16S rDNA of and in the total DNA of yeasts. RESULTS Yeasts were identified as members of seven genera; and Intravacuolar bacteria were stained green with a bacterial viability kit, revealing that they were alive. Immunofluorescence assay confirmed the identity of intracellular and spp. PCR results revealed that among the 32 isolated yeasts, 53% were -positive, 6% were -positive, 18.7% were positive for both, and 21.8% were negative for both. CONCLUSION Detection of - and -16S rDNA in yeast isolates from dried fruits, and commercial foods showed the occurrence of more than one kind of endosymbiotic bacterium in yeasts' vacuoles. While the establishment of and in yeast is a sophisticated survival strategy, yeast serves as a potent bacterial reservoir.