16S-23S rRNA intergenic spacer region sequence variation in Streptococcus thermophilus and related dairy streptococci and development of a multiplex ITS-SSCP analysis for their identification.
The 16S-23S rRNA internal transcribed spacer (ITS) region of several Streptococcus thermophilus strains and some related dairy streptococci, S. macedonicus, S. salivarius and S. bovis, was analysed by sequence analysis. All the Streptococcus species were easily discriminated on the basis of sequence variations principally located upstream and downstream of the region encompassing the double-stranded processing sites and the tRNA(Ala) gene. Comparison between tRNA(Ala) gene sequences highlighted a high level of sequence conservation among the Streptococcus species investigated despite their belonging to separated phylogenetic clusters, i.e. the S. salivarius and S. bovis rRNA groups. A low but significant degree of variability was detected among the S. thermophilus strains, allowing the identification of four different ITS sequences. Similarity analysis of the ITS sequences showed that the Streptococcus species were clustered in two main branches, one containing S. macedonicus and S. bovis strains, and one containing S. thermophilus and S. salivarius strains. With the aim of developing a rapid tool for the identification of the dairy streptococci species a multiplex ITS-SSCP analysis of two discrete regions within the ITS locus was carried out.
Mora
Diego
D
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, sezione Microbiologia Industriale, Università degli Studi di Milano, Milano, Italy.
Ricci
Giovanni
G
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, sezione Microbiologia Industriale, Università degli Studi di Milano, Milano, Italy.
Guglielmetti
Simone
S
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, sezione Microbiologia Industriale, Università degli Studi di Milano, Milano, Italy.
Daffonchio
Daniele
D
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, sezione Microbiologia Agraria, Alimentare e Ecologica, Università degli Studi di Milano, Milano, Italy.
Fortina
Maria Grazia
MG
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, sezione Microbiologia Industriale, Università degli Studi di Milano, Milano, Italy.
D015373:Bacterial Typing Techniques; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D003611:Dairy Products / Q000382:microbiology*; D003612:Dairying; D014644:Genetic Variation; D006358:Hot Temperature; D018807:Polymorphism, Single-Stranded Conformational; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D013045:Species Specificity; D013291:Streptococcus / Q000145:classification* / Q000235:genetics
D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S