Isolation and molecular identification of <i>Bifidobacteria</i> from industrial and traditional yoghurt and cheese in three cities of Razavi Khorasan Province, Iran

Abstract Bifidobacteria are important probiotics with recognised health benefits and widespread use in the food industry. This study aimed to isolate and identify Bifidobacteria from industrial and traditional yoghurt and cheese products in Razavi Khorasan Province, Iran, using selective culture and polymerase chain reaction (PCR). Samples were analysed on trans-galactosylated oligosaccharide (TOS), bifidus selective medium (BSM), and all-purpose tween (APT) agar, with enumeration assessed by independent t-tests. Morphological features were examined microscopically, and isolates were confirmed by PCR targeting the 16S rRNA gene. BSM agar showed the greatest discriminatory power, detecting significantly higher counts in industrial yoghurt compared with traditional yoghurt and, conversely, higher counts in traditional cheese compared with industrial cheese (p &amp;lt; .05). TOS and APT agar were less effective, showing no significant differences between product types. PCR demonstrated high concordance for isolates from BSM and APT agar (88% sensitivity), but lower concordance for TOS agar (33%), which also produced occasional false positives. These results support their potential use in industrial probiotic development and provide nutritional benefits similar to those of commercial probiotic dairy products by confirming that traditional dairy products are promising reservoirs of probiotic Bifidobacteria.