title: Genotyping of Streptococcus thermophilus strains isolated from traditional Egyptian dairy products by sequence analysis of the phosphoserine phosphatase (serB) gene with phenotypic characterizations of the strains.
abstract: OBJECTIVE
  To develop a new, simplified genotyping method for examining the genetic diversity of Streptococcus thermophilus strains isolated from traditional Egyptian fermented dairy products and to characterize phenotypic traits of those strains related to their potential use in bioprocessing applications.
  
  
  RESULTS
  A novel, simplified approach was developed for genotyping Strep. thermophilus involving the analysis of nucleotide sequence variations within a housekeeping gene encoding the phosphoserine phosphatase (SerB). Using this method, it was possible to identify ten genotypes involving diverse serB alleles among 54 Strep. thermophilus isolates cultured from Egyptian dairy products. These isolates harboured five de novo serB alleles that have not been detected in other Strep. thermophilus strains, deposited in a multilocus sequence typing (MLST) database. To assess distinct genotypes of the organism with phenotypic traits relevant to their potential use in industry, Strep. thermophilus strains were all subjected to a series of phenotypic characterizations. The strains were found to exhibit phenotypic diversity in terms of their ability to ferment lactose and galactose, express urease activity, produce exopolysaccharides and develop acidity.
  
  
  CONCLUSIONS
  The analysis of nucleotide sequence variations within the serB gene could serve as a suitable tool for probing diverse genotypes of Strep. thermophilus. Streptococcus thermophilus isolates associated with traditional Egyptian dairy products show high degree of genetic and phenotypic diversity.
  
  
  CONCLUSIONS
  This study presents a novel, simplified procedure based on serB nucleotide sequencing for genotyping Strep. thermophilus. It also provides a pool of phenotypically diverse Strep. thermophilus cultures, from which certain strains could be selected for use in bioprocessing applications including the preparation of fermented dairy products.
authors.affiliation: Food Safety and Microbial Physiology Laboratory, Dairy Department, Faculty of Agriculture, Mansoura University, Mansoura, Egypt. wmel_sharoud@mans.edu.eg
authors.forename: W M
authors.initials: WM
authors.lastname: El-Sharoud
authors.forename: C
authors.initials: C
authors.lastname: Delorme
authors.forename: M S
authors.initials: MS
authors.lastname: Darwish
authors.forename: P
authors.initials: P
authors.lastname: Renault
mesh_terms: D001483:Base Sequence; D003611:Dairy Products / Q000382:microbiology*; D004534:Egypt; D014644:Genetic Variation; D005838:Genotype; D008969:Molecular Sequence Data; D010641:Phenotype; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D016415:Sequence Alignment; D048249:Streptococcus thermophilus / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D010744:Phosphoric Monoester Hydrolases; C022394:phosphoserine phosphatase