1. Home
  2. Science & Research
  3. About Science & Research at FDA
  4. The FDA Science Forum
  5. Cell Concentration Dependency of Survival on Drying in Salmonella Species
  1. The FDA Science Forum

2021 FDA Science Forum

Cell Concentration Dependency of Survival on Drying in Salmonella Species

Authors:
Poster Author(s)
Streufert, Rachel, FDA/CFSAN; Salazar, Joelle K., FDA/CFSAN; Keller, Susanne E., FDA/CFSAN
Center:
Contributing Office
Center for Food Safety and Applied Nutrition

Abstract

Poster Abstract

Salmonella enterica is well-known for its ability to survive drying and persist in low-moisture environments. Growth as sessile cells, quorum sensing, and biofilm formation have been examined for possible links, however, the actual mechanisms involved remain elusive. The purpose of this study was to determine the effect of initial cell concentration or soluble quorum sensing compounds on the desiccation survival of Salmonella when grown as sessile cells. Salmonella was grown on TSBYE with agar and harvested using BPW. Cell suspensions (11.08±0.10 log CFU/mL) were divided into portions and treated as follows: one portion centrifuged and filtered to remove cells to create conditioned BPW (C-BPW) and a second portion heat-treated to kill cells (K-BPW). C-BPW, K-BPW, or control BPW were used to serially dilute the original harvested Salmonella. Cells (0.1 mL) were applied to membrane filters at concentrations of approximately 10 (undiluted), 8, 6 or 4 log CFU, dried (ambient) for 1 d, then stored at 25°C/33% RH. Cells were recovered from filters using BPW and cultivated on TSAYE. Data were compared via ANOVA (p≤0.05). After 1 and 7 d storage, populations of undiluted Salmonella did not significantly change with an overall decrease of 0.25-0.50 log. When the initial Salmonella population was decreased, survival decreased compared to undiluted when cells were diluted in BPW or C-BPW but not when diluted with K-BPW. At the lowest dilution (4 log CFU), losses at 1 d were 1.97±0.09 for C-BPW, 1.30±0.50 for BPW, but only 0.33±0.06 log CFU for K-BPW. After 7 d, losses increased for cells diluted in C-BPW and BPW (>4 log CFU), whereas those diluted in K-BPW lost only 0.40±0.01 log CFU. Survival of Salmonella during drying appears cell concentration dependent and may be aided by specific non-soluble components associated with harvested cells.

Poster Image
Preview image of the scientific poster. For more information, please refer to the abstract or download the PDF version of the poster.
Back to Top