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The aim of this paper was to detect <italic>Lactobacillus delbrueckii</italic> and <italic>Streptococcus thermophilus</italic> using real-time quantitative PCR assay in 7-day ripening cheese produced from unpasteurised milk. Real-time quantitative PCR assays were designed to identify and enumerate the chosen species of lactic acid bacteria (LAB) in ripened cheese. The results of molecular quantification and classic bacterial enumeration showed a high level of similarity proving that DNA extraction was carried out in a proper way and that genomic DNA solutions were free of PCR inhibitors. These methods revealed the presence of <italic>L. delbrueckii</italic> and <italic>S. thermophilus</italic>. The real-time PCR enabled quantification with a detection of 101–103 CFU/g of product. qPCR-standard curves were linear over seven log units down to 101 copies per reaction; efficiencies ranged from 77.9% to 93.6%. Cheese samples were analysed with plate count method and qPCR in parallel. Compared with the classic plate count method, the newly developed qPCR method provided faster and species specific identification of two dairy LAB and yielded comparable quantitative results.
</abstract>

The aim of this paper was to detect Lactobacillus delbrueckii and Streptococcus thermophilus using real-time quantitative PCR assay in 7-day ripening cheese produced from unpasteurised milk. Real-time quantitative PCR assays were designed to identify and enumerate the chosen species of lactic acid bacteria (LAB) in ripened cheese. The results of molecular quantification and classic bacterial enumeration showed a high level of similarity proving that DNA extraction was carried out in a proper way and that genomic DNA solutions were free of PCR inhibitors. These methods revealed the presence of L. delbrueckii and S. thermophilus. The real-time PCR enabled quantification with a detection of 101–103 CFU/g of product. qPCR-standard curves were linear over seven log units down to 101 copies per reaction; efficiencies ranged from 77.9% to 93.6%. Cheese samples were analysed with plate count method and qPCR in parallel. Compared with the classic plate count method, the newly developed qPCR method provided faster and species specific identification of two dairy LAB and yielded comparable quantitative results.

Identification of <italic>Lactobacillus delbrueckii</italic> and <italic>Streptococcus thermophilus</italic> Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

Lomza State University of Applied Sciences

Polish Journal of Microbiology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Identification of  and  Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

The aim of this paper was to detect Lactobacillus delbrueckii and Streptococcus thermophilus using real-time quantitative PCR assay in 7-day ripening cheese...

Identification of Lactobacillus delbrueckii and Streptococcus thermophilus Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

Published Online: Dec 04, 2017

Page range: 491 - 499

Received: Mar 28, 2017

Accepted: May 23, 2017

DOI: https://doi.org/10.5604/01.3001.0010.7041

Keywords
artisanal cheese microflora, LAB identification

© 2017 MILENA A. STACHELSKA published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Identification of Lactobacillus delbrueckii and Streptococcus thermophilus Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

Published Online: Dec 04, 2017

Page range: 491 - 499

Received: Mar 28, 2017

Accepted: May 23, 2017

DOI: https://doi.org/10.5604/01.3001.0010.7041

Keywordsartisanal cheese microflora, LAB identification

© 2017 MILENA A. STACHELSKA published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
artisanal cheese microflora, LAB identification