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Viable but nonculturable state of foodborne pathogens in grapefruit juice: a study of laboratory.
MedLine Citation:
PMID:  20932087     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
Several foodborne human pathogens, when exposed to harsh conditions, enter viable but nonculturable (VBNC) state; however, still open is the question whether VBNC pathogens could be a risk for public health, because, potentially, they can resuscitate. Moreover, cultural methods for food safety control were not able to detect VBNC forms of foodborne bacteria. Particularly, it has not been established whether food chemophysical characteristics can induce VBNC state in contaminating pathogen bacterial populations, especially in food, such as salads and fresh fruit juices, not subjected to any decontamination treatment. In this preliminary study, we intentionally contaminated grapefruit juice to determine whether pathogen bacteria could enter VNBC state. In fact, grapefruit juice contains natural antimicrobial compounds, has an average pH of about 3 and low content in carbohydrates. Such characteristics make grapefruit juice a harsh environment for microbial survival. For this purpose, Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium ATCC 14028, Listeria monocytogenes ATCC 7644, and Shigella flexneri ATCC 12022, at two different inoculum sizes, have been used. Viability by the LIVE/DEAD BacLight Bacterial Viability kit and culturability by plate counts assay were monitored, whereas "resuscitation" of nonculturable populations was attempted by inoculation in nutrient-rich media. The data showed that L. monocytogenes lost both culturability and viability and did not resuscitate within 24 h independently on inoculum size, whereas E. coli O157:H7 was able to resuscitate after 24 h but did not after 48 h. Salmonella Typhimurium and S. flexneri, depending on inoculum size, lost culturability but maintained viability and were able to resuscitate; moreover, S. flexneri was still able to form colonies after 48 h at high inoculum size. In conclusion, entry into VBNC state differs on the species, depending, in turn, on inoculum size and time of incubation.
Authors:
Marco Sebastiano Nicolò; Angela Gioffrè; Santina Carnazza; Giuseppe Platania; Isabella Di Silvestro; Salvatore Pietro Paolo Guglielmino
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Publication Detail:
Type:  Journal Article     Date:  2010-10-08
Journal Detail:
Title:  Foodborne pathogens and disease     Volume:  8     ISSN:  1556-7125     ISO Abbreviation:  Foodborne Pathog. Dis.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101120121     Medline TA:  Foodborne Pathog Dis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11-7     Citation Subset:  IM    
Affiliation:
Dipartimento di Scienze della Vita Marcello Malpighi, Sezione di Scienze Microbiologiche, Genetiche e Molecolari, Università di Messina, Messina, Italy.
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