The Isolation and Identification of Dominant Lactic Acid Bacteria by the Sequencing of the 16S rRNA in Traditional Cheese (Khiki) in Semnan, Iran

Abstract

Background: Identification of the dominant lactic acid bacteria involved in the production of traditional cheese in Semnan could be the initiative to protect national genetic resources and produce industrial cheese with desirable texture and organoleptic characteristics similar to traditional cheeses. The present study aimed to determine the biochemical, physiological, and phenotypic properties of the dominant strains of the lactic acid bacteria (LAB) isolated from the traditional cheese in Semnan, Iran using 16S rRNA gene sequence analysis. Methods: In total, 14 cheese samples were randomly collected from the northern countryside of Semnan, Iran. The isolated gram-positive and catalase-negative colonies were analyzed in terms of morphology, culture, physiology, biochemical properties, and carbohydrate fermentation pattern. Following that, the LAB isolates were identified based on 16S rRNA gene sequence analysis, and a phylogenetic tree was drawn for the bacterial strains. Results: In this study, 105 isolates were determined, 58 of which (55.24%) belonged to the genus Lactobacilli, and 47 isolates (44.76%) belonged to the genus Enterococci. According to the biochemical tests and 16S rDNA sequencing, the identified dominant Lactobacillus species included L. plantarum (53.6%), L. paracasei (32.7%), and L. casei (13.7%). In addition, most of the Enterococcus species were E. faecium (74.47%) and E. durans (25.53%). Conclusion: According to the results, exploring the microbiological diversity of traditional cheese could contribute to the selection of proper bacterial strains for the manufacturing of products with consistent quality and original taste on an industrial scale.