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Detection and Viability of Lactococcus lactis throughout Cheese Ripening
Recent evidences highlighted the presence of Lactococcus lactis during late cheese ripening. For this reason, the role of this microorganism, well known as dairy starter, should be reconsidered throughout cheese manufacturing and ripening. Thus, the main objective of this study was to develop a RT-q...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Public Library of Science
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4266610/ https://www.ncbi.nlm.nih.gov/pubmed/25503474 http://dx.doi.org/10.1371/journal.pone.0114280 |
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author | Ruggirello, Marianna Dolci, Paola Cocolin, Luca |
author_facet | Ruggirello, Marianna Dolci, Paola Cocolin, Luca |
author_sort | Ruggirello, Marianna |
collection | PubMed |
description | Recent evidences highlighted the presence of Lactococcus lactis during late cheese ripening. For this reason, the role of this microorganism, well known as dairy starter, should be reconsidered throughout cheese manufacturing and ripening. Thus, the main objective of this study was to develop a RT-qPCR protocol for the detection, quantification and determination of the viability of L. lactis in ripened cheese samples by direct analysis of microbial nucleic acids. Standard curves were constructed for the specific quantification of L. lactis in cheese matrices and good results in terms of selectivity, correlation coefficient and efficiency were obtained. Thirty-three ripened cheeses were analyzed and, on the basis of RNA analysis, twelve samples showed 10(6) to 10(8) CFU of L. lactis per gram of product, thirteen from 10(3) to 10(5) CFU/g, and in eight cheeses, L. lactis was not detected. Traditional plating on M17 medium led to loads ranging from 10(5) to 10(9) CFU/g, including the cheese samples where no L. lactis was found by RT-qPCR. From these cheeses, none of the colonies isolated on M17 medium was identified as L. lactis species. These data could be interpreted as a lack of selectivity of M17 medium where colony growth is not always related to lactococcal species. At the same time, the absence or low abundance of L. lactis isolates on M17 medium from cheese where L. lactis was detected by RT-qPCR support the hypothesis that L. lactis starter populations are mainly present in viable but not culturable state during ripening and, for this reason, culture-dependent methods have to be supplemented with direct analysis of cheese. |
format | Online Article Text |
id | pubmed-4266610 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-42666102014-12-26 Detection and Viability of Lactococcus lactis throughout Cheese Ripening Ruggirello, Marianna Dolci, Paola Cocolin, Luca PLoS One Research Article Recent evidences highlighted the presence of Lactococcus lactis during late cheese ripening. For this reason, the role of this microorganism, well known as dairy starter, should be reconsidered throughout cheese manufacturing and ripening. Thus, the main objective of this study was to develop a RT-qPCR protocol for the detection, quantification and determination of the viability of L. lactis in ripened cheese samples by direct analysis of microbial nucleic acids. Standard curves were constructed for the specific quantification of L. lactis in cheese matrices and good results in terms of selectivity, correlation coefficient and efficiency were obtained. Thirty-three ripened cheeses were analyzed and, on the basis of RNA analysis, twelve samples showed 10(6) to 10(8) CFU of L. lactis per gram of product, thirteen from 10(3) to 10(5) CFU/g, and in eight cheeses, L. lactis was not detected. Traditional plating on M17 medium led to loads ranging from 10(5) to 10(9) CFU/g, including the cheese samples where no L. lactis was found by RT-qPCR. From these cheeses, none of the colonies isolated on M17 medium was identified as L. lactis species. These data could be interpreted as a lack of selectivity of M17 medium where colony growth is not always related to lactococcal species. At the same time, the absence or low abundance of L. lactis isolates on M17 medium from cheese where L. lactis was detected by RT-qPCR support the hypothesis that L. lactis starter populations are mainly present in viable but not culturable state during ripening and, for this reason, culture-dependent methods have to be supplemented with direct analysis of cheese. Public Library of Science 2014-12-15 /pmc/articles/PMC4266610/ /pubmed/25503474 http://dx.doi.org/10.1371/journal.pone.0114280 Text en © 2014 Ruggirello et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Ruggirello, Marianna Dolci, Paola Cocolin, Luca Detection and Viability of Lactococcus lactis throughout Cheese Ripening |
title | Detection and Viability of Lactococcus lactis throughout Cheese Ripening |
title_full | Detection and Viability of Lactococcus lactis throughout Cheese Ripening |
title_fullStr | Detection and Viability of Lactococcus lactis throughout Cheese Ripening |
title_full_unstemmed | Detection and Viability of Lactococcus lactis throughout Cheese Ripening |
title_short | Detection and Viability of Lactococcus lactis throughout Cheese Ripening |
title_sort | detection and viability of lactococcus lactis throughout cheese ripening |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4266610/ https://www.ncbi.nlm.nih.gov/pubmed/25503474 http://dx.doi.org/10.1371/journal.pone.0114280 |
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