Role of sigB and osmolytes in desiccation survival of Listeria monocytogenes in simulated food soils on the surface of food grade stainless steel. (April 2015)

• Record Type: Journal Article
• Authors: Huang, Yannan; Ells, Timothy C.; Truelstrup Hansen, Lisbeth
• Is Part Of: Food microbiology. Volume 46(2015:Apr.)
• Page Start: 443
• Page End: 451
• Publication Date: 2015-04
• Subjects: Listeria monocytogenes -- Desiccation stress -- Osmotic stress -- SigB regulon -- Osmolytes -- Salt -- Stainless steel -- Stress response; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2014.09.007
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: This research aimed to determine whether the SigB (σ B ) regulon and osmolytes impact the survival of the foodborne pathogen, Listeria monocytogenes, during desiccation in simulated food soils with varying salt and nutrient contents on food grade stainless steel (SS) surfaces. L. monocytogenes 568 (Lm568, serotype 1/2a), its isogenic sigB mutant (Δ sigB ) and the back-complemented Δ sigB were desiccated in BHI, TSB with 1% glucose (TSB-glu), peptone physiological saline (PPS) and minimal media (MM) for 21 days at 43% relative humidity (RH) and 15 °C on SS. The effect of food related osmolytes (proline, betaine and carnitine) on desiccation survival was studied by (a) pre-culturing strains in MM with an osmolyte followed by desiccation in MM and (b) by desiccating strains in MM with an osmolyte. Desiccation survival of L. monocytogenes was positively correlated to the nutrient and osmolyte concentrations in the desiccation substrates. Initial Lm568 levels of 8 Log(CFU/cm 2 ) decreased by 0.9 Log(CFU/cm 2 ) in BHI and 1.1–2.9 Log(CFU/cm 2 ) in TSB-glu, PPS and MM after 21 days. Comparatively, the initial survival of Δ sigB was reduced in PS and MM, while no differences were observed among the three strains in BHI and TSB-glu. Pre-culture in osmolyte containing MM enhanced ( p < 0.05) desiccation survival of all strains. Desiccation in osmolyte-containing MM improved desiccation survival of all strains, albeit the protection was less than that observed after pre-culture with the osmolytes. Complementation of the Δs igB mutant restored the wildtype phenotype. In conclusion, this work shows the protective effect of osmolytes in desiccation survival of L. monocytogenes, while the σ B regulon only improved the initial survival in nutrient and osmolyte poor environments. Highlights: Deletion of sigB decreased initial desiccation survival in nutrient poor substrates. Long-term desiccation survival of Listeria monocytogenes was not affected by σ B . Pre-culture with osmolytes enhanced subsequent listerial desiccation survival. Desiccation with osmolytes offered less protection than pre-culture. Osmolytes but not σ B majorly impact desiccation survival of L. monocytogenes.