Phenotypic and genotypic diversity of dominant lactic acid bacteria isolated from traditional yoghurts produced by tribes of Iran

ABSTRACT

Morphological, biochemical and molecular characteristics were studied to identify dominant lactic acid bacteria [LAB], isolated from traditional yoghurts produced by tribes of Iran. From 60 yoghurt samples, a total of 137 LAB isolates were determined, in which 66 and 71 were identified as lactic acid cocci and bacilli, respectively. Biochemical tests showed the occurrence of 9.76% mesophilic homofermentative, 10.98% mesophilic hetrofermentative, 26.83% thermophilic homofermentative and 47.56% mesophilic homofermentative cocci. As for lactic acid bacilli, mesophilic facultative hetrofermentative [26%]; thermophilic obligate homofermentative [56%]; mesophilic obligate hetrofermentative [18%] were found. Genetically the presence of the following species were verified E. faecium, E. faecalis, E. durans; L. lactis subsp. lactis/ St. thermophilus', Lb. delbruecki subsp. bulgaricus; Lb. brevis/ Lb. diolivorans'Lb. helveticus; Lb. jensenii; Lb. plantarum. 9% of the Lactobacillus isolates showed incompatible results between phenotypic and genotypic characteristics. From the cocci isolates, 38.46% showed identical results between phylogenetic characteristics. The current study constitutes the first step in the designing process of LAB starter cultures, to protect the typical organoleptic characteristics of traditional yoghurt. The results could also be used to introduce new starter cultures for commercial use