Genetic diversity and phylogenetic relationships of Streptococcus thermophilus isolates from traditional Turkish yogurt: multilocus sequence typing (MLST)


Kiraz D., Özcan A., YIBAR A., DERTLİ E.

Archives of Microbiology, vol.206, no.3, 2024 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 206 Issue: 3
  • Publication Date: 2024
  • Doi Number: 10.1007/s00203-024-03850-7
  • Journal Name: Archives of Microbiology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, CAB Abstracts, Chemical Abstracts Core, EMBASE, Environment Index, Food Science & Technology Abstracts, Veterinary Science Database
  • Keywords: Genetic diversity, Multilocus sequence typing (MLST), Phylogenetic analysis, Probiotics, Streptococcus thermophilus, Traditional yogurt
  • Yıldız Technical University Affiliated: Yes

Abstract

Yogurt, a globally consumed fermented dairy product, is recognized for its taste and potential health benefits attributed to probiotic bacteria, particularly Streptococcus thermophilus. In this study, we employed Multilocus Sequence Typing (MLST) to investigate the genetic diversity and phylogenetic relationships of 13 S. thermophilus isolates from traditional Turkish yogurt samples. We also assessed potential correlations between genetic traits and geographic origins. The isolates were identified as S. thermophilus using VITEK® MALDI-TOF MS, ribotyping, and 16S rRNA analysis methods. MLST analysis revealed 13 different sequence types (STs), with seven new STs for Turkey. The most prevalent STs were ST/83 (n = 3), ST/135 (n = 2), and ST/134 (n = 2). eBURST analysis showed that these isolates mainly were singletons (n = 7) defined as sequence types (STs) that cannot be assigned to any group and differ at two or more alleles from every other ST in the sample. This information suggests that the isolates under study were genetically distinct from the other isolates in the dataset, highlighting their unique genetic profiles within the population. Genetic diversity analysis of ten housekeeping genes revealed polymorphism, with some genes showing higher allelic variation than others. Tajima’s D values suggested that selection pressures differed among these genes, with some being more conserved, likely due to their vital functions. Phylogenetic analysis revealed distinct genetic diversity between Turkish isolates and European and Asian counterparts. These findings demonstrate the genetic diversity of S. thermophilus isolates in Turkish yogurt and highlight their unique evolutionary patterns. This research contributes to our understanding of local microbial diversity associated with yogurt production in Turkey and holds the potential for identifyic strains with enhanced functional attributes.