Document Detail

Quantification of Enterococcus italicus in traditional Italian cheeses by fluorescence whole-cell hybridization.
MedLine Citation:
PMID:  18562146     Owner:  NLM     Status:  MEDLINE    
The objective of this work was to investigate the spread of Enterococcus italicus in cheese. For this purpose, a fluorescence whole-cell hybridization protocol (FWCH) with a 16S rRNA probe was optimized to evaluate the presence and abundance of this organism in artisanal Italian cheeses. The FWCH method avoided the quantification problems using classical plate count techniques related to the well-known difficulties to cultivate E. italicus in selective enterococci media. After probe and FWCH optimization, 10 commercially available Italian semi-hard cheeses made with raw ewe or cow milk without starter addition were analyzed. All of them were subjected to FWCH experiments and six of them gave positive results with the probe, i.e. the E. italicus content was >4 log cells/g according to the detection limit of FWCH. Counts showed that E. italicus was present at levels ranging from 5.91+/-0.17 to 7.34+/-0.14 log cells/g; such levels were similar to, or even higher than, the total enterococci counted from the corresponding cheeses using kanamycin aesculin azide agar. The overall reliability of the FWCH method was tested by species-specific PCR. The positive amplification of the expected 323 bp fragment from both a cheese matrix and cell bulks of cheese samples containing high loads of this organism (as determined by FWCH counts) and the successful isolation of E. italicus strains from the above cheeses provided definitive proof of both probe specificity and the presence of this organism in cheeses. Although there is very little available quantitative data on the incidence of E. italicus in cheese, or its role in product quality, this study showed a wide diffusion of this organism in artisanal cheeses, where secondary non-starter lactic acid bacterial microflora, which enterococci belong to, may become dominant during ripening.
Maria Emanuela Fornasari; Lia Rossetti; Chiara Remagni; Giorgio Giraffa
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Publication Detail:
Type:  Evaluation Studies; Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-06-17
Journal Detail:
Title:  Systematic and applied microbiology     Volume:  31     ISSN:  0723-2020     ISO Abbreviation:  Syst. Appl. Microbiol.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-07-18     Completed Date:  2008-09-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8306133     Medline TA:  Syst Appl Microbiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  223-30     Citation Subset:  IM    
Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per le Produzioni Foraggere e Lattiero-Casearie, Settore di Ricerca Lattiero-Caseario, Via Lombardo 11, Lodi, Italy.
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MeSH Terms
Bacteriological Techniques
Cheese / microbiology*
Colony Count, Microbial / methods
DNA Probes
DNA, Bacterial / analysis,  isolation & purification
Enterococcus / classification,  cytology*,  genetics,  isolation & purification*
In Situ Hybridization, Fluorescence / methods*
Polymerase Chain Reaction
Species Specificity
Reg. No./Substance:
0/DNA Probes; 0/DNA, Bacterial

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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