Molecular methods for identification of Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus using methionine biosynthesis and 16S rRNA genes

Date

2008-11-01

Author

Cebeci, Aysun
Gültekin, Güzin Candan

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Yoghurt and starter culture producers are still searching strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus to produce healthier yogurt with longer shelf life, better texture, taste and quality. However, selective identification of Lb. delbrueckii subsp. bulgaricus and Strep. thermophilus from a mixed population using microbiological and biochemical methods is difficult, time consuming and may not be accurate. In this study, a quick, sensitive and accurate method is proposed to identify both Lb. delbrueckii subsp. bulgaricus and Strep. thermophilus using PCR. The method is comprised of two parts. In the first part, methionine biosynthesis genes, known to be present in both species were partially amplified by designed primers (cysmet2F and cysmet2R). Partial amplification of the methionine biosynthesis gene which gives 700 bp fragment resulted in selective identification of Lb. bulgaricus and Strep. thermophilus. All 16 Lb. bulgaricus and 6 Strep. thermophilus isolates assessed by this method gave the expected amplification. On the other hand, further analysis of other closely related species with the same primers have indicated that the same product was also amplified in two more lactobacilli namely, Lb. delbrueckii subsp. lactis and Lb. helveticus species. Thus, in the second part of the method, further differentiation of Lb. delbrueckii subsp. bulgaricus and Strep. thermophilus from each other and these species was achieved using restriction analysis of 16S rRNA gene with EcoRl.

Subject Keywords

Food Science, Animal Science and Zoology, General Medicine

URI

https://hdl.handle.net/11511/47444

Journal

JOURNAL OF DAIRY RESEARCH

DOI

https://doi.org/10.1017/s0022029908003543

Collections

Department of Food Engineering, Article

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Citation Formats

A. Cebeci and G. C. Gültekin, “Molecular methods for identification of Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus using methionine biosynthesis and 16S rRNA genes,” JOURNAL OF DAIRY RESEARCH, pp. 392–398, 2008, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/47444.