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Cold and carbon dioxide used as multi‐hurdle preservation do not induce appearance of viable but non‐culturable Listeria monocytogenes
Author(s) -
Li J.,
Kolling G.L.,
Matthews K.R.,
Chikindas M.L.
Publication year - 2003
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2003.01795.x
Subject(s) - library science , state (computer science) , computer science , algorithm
Aims: To study whether the exposure to cold (4°C) and carbon dioxide which results in the elongation of Listeria cells, induces a viable but nonculturable (VBNC) state. Methods and Results: When cold and CO 2 stressed L. monocytogenes were observed under a fluorescence microscope, using the LIVE/DEAD Bac Light™ bacteria viability kit (Molecular Probes, Eugene, OR, USA), the healthy, mildly injured, and the putative VBNC cells accounted for 31·0% of the stressed cell population. By using the selective plate count, 31·4% of the same stressed cell population was found to be healthy and mildly injured (putative VBNC cells not included). If there were VBNC state cells present, we should have observed a significant difference between the above two numbers. In fact, there was no significant difference between the results obtained from those two methods. Conclusions: There were no VBNC state cells observed in the stressed cell population. We conclude that cold and CO 2 do not induce L. monocytogenes to enter a VBNC state. Significance and Impact of the Study: Cold and modified atmospheres are widely used in fresh muscle food and fruit preservation. Whether they would induce L. monocytogenes into a VBNC state is of a great concern for microbial food safety.