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The persistence of S almonella following desiccation under feed processing environmental conditions: a subject of relevance
Author(s) -
Habimana O.,
Nesse L.L.,
Møretrø T.,
Berg K.,
Heir E.,
Vestby L.K.,
Langsrud S.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12308
Subject(s) - viable but nonculturable , salmonella , desiccation , biology , persistence (discontinuity) , microbiology and biotechnology , population , rpos , bacteria , food science , ecology , genetics , medicine , gene , geotechnical engineering , environmental health , engineering , gene expression , promoter
Although S almonella persistence has been predominantly linked to biofilm formation, the physiological state of S almonella should also be considered as a possible pathway for persistence and survival in the feed industry. Hence, the purpose of this study was to assess the extent of viability of Salmonella cells through long‐term desiccation periods under conditions typically found in feed processing environments, and whether these same cells could resuscitate and cause salmonellosis in vivo . We showed that upon desiccation, S almonella A gona, a representative feed industry isolate and S almonella Typhimurium ATCC 14028, a laboratory strain, were induced into a nonculturable state at 35 and 85% relative humidity conditions, at defined temperatures of 30 and 12°C, respectively. Although the reduction in culturable cells was more than 6 log 10 , metabolic activity was found in more than 1% of the population. Desiccation‐induced nonculturable S alm. Typhimurium could not be revived and were nonvirulent in a mouse model following infection through oral gavage. These results suggest that the specific conditions for reviving nonculturable S almonella after long periods of desiccation are yet to be fully identified. The need for mapping key factors involved in the persistence of S almonella would help better detect it and improve feed safety measures. Significance and Impact of the Study While S almonella has been shown to persist for years in feed processing environments, it is still unknown how temperature and humidity affect the persistence of S almonella cells over time in terms of their metabolic states and cultivability. Here, we show that long‐term exposure to feed processing environmental conditions induces S almonella into a nonculturable state even though about 1% of the population remains metabolically active. This has significant implications when monitoring S almonella from the environment which could yield false‐negative results using conventional pre‐enrichment detection methods.