In a viable but nonculturable (VBNC) state, bacteria are no longer culturable on standard laboratory media, but still, remain a pathogenic potential and present possible health risks. In this study, we investigated ampicillin's ability, which is commonly used in dairy cattle disease treatment, to induce Cronobacter sakazakii into the VBNC state. After treatment with ampicillin, the counts of culturable cells decreased from 10 CFU/mL to an undetected level 7-30 days post-treatment. Meanwhile, viable cells were still approximately 10-10 cells/mL, and could be resuscitated under appropriate conditions. Fluorescence microscopy showed that VBNC cell maintained apparent cellular integrity, but that the morphology of VBNC cells differed visibly from that of normal cells. Moreover, the respiratory chain activity of VBNC cells were confirmed by flow cytometry (FCM) analysis, suggesting that cells in a VBNC state were physiologically active. Finally, transcriptomics analysis and real-time PCR (qPCR) validation were used to explore the underlying mechanisms of VBNC cell formation. Over-expression of relA, lon, ppx, and ppk in the toxin-antitoxin (TA) trigger system contributed to VBNC cell formation. In the TA trigger system, RelA and exopolyphosphatases/guanosine pentaphosphate phosphohydrolases (PPX/GPPA) synthesize ppGpp, which activates polyphosphate kinase (PPK), the cellular enzyme that accumulates plyphosphate (PolyP). PolyP combines with and stimulates Lon to degrade the antitoxins, thereby activating the toxins that induce a VBNC state. The results of our research will facilitate a better understanding of the survival strategies that bacteria develop to deal with ampicillin pressure and the health risks associated with VBNC Cronobacter sakazakii induced by antibiotics.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2020.108819 | DOI Listing |
Nat Commun
January 2025
Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
Recalcitrant bacterial infections can be caused by various types of dormant bacteria, including persisters and viable but nonculturable (VBNC) cells. Despite their clinical importance, we know fairly little about bacterial dormancy development and recovery. Previously, we established a correlation between protein aggregation and dormancy in Escherichia coli.
View Article and Find Full Text PDFFront Cell Infect Microbiol
January 2025
Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China.
[This corrects the article DOI: 10.3389/fcimb.2024.
View Article and Find Full Text PDFAnal Chem
January 2025
Department of Food Science and Agricultural Chemistry, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3 V9, Canada.
is a leading foodborne pathogen that may enter a viable but nonculturable (VBNC) state to survive under environmental stresses, posing a significant health concern. VBNC cells can evade conventional culture-based detection methods, while viability-based assays are usually hindered by low sensitivity, insufficient specificity, or technical challenges. There are limited studies analyzing VBNC cells at the single-cell level for accurate detection and an understanding of their unique behavior.
View Article and Find Full Text PDFEnviron Microbiol
January 2025
Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland.
Legionella pneumophila, the causative agent of Legionnaires' disease, employs the Icm/Dot Type IV secretion system (T4SS) to replicate in amoebae and macrophages. The opportunistic pathogen responds to stress by forming 'viable but non-culturable' (VBNC) cells, which cannot be detected by standard cultivation-based techniques. In this study, we document that L.
View Article and Find Full Text PDFFront Microbiol
December 2024
Meat Safety and Quality Research Unit, U.S. Department of Agriculture, U.S. Meat Animal Research Center, Clay Center, NE, United States.
Recent application of whole genome sequencing in the investigation of foodborne illness outbreaks has facilitated the identification of Reoccurring, Emerging, or Persistent (REP) bacterial strains that have caused illnesses over extended periods of time. Here, the complete genomes of two O157:H7 (EcO157) outbreak strains belonging to REPEXH01 and REPEXH02, respectively, were sequenced and annotated. Comparative genomics and phenotypic analyses were carried out to identify REP-associated traits.
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