This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hornbæk, T. Articles by Budde, B. B. Search for Related Content PubMed PubMed Citation Articles by Hornbæk, T. Articles by Budde, B. B. Agricola Articles by Hornbæk, T. Articles by Budde, B. B.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, February 2006, p. 1631-1638, Vol. 72, No. 2
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.2.1631-1638.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Two Subpopulations of Listeria monocytogenes Occur at Subinhibitory Concentrations of Leucocin 4010 and Nisin

Tina Hornbæk,^1, Per B. Brockhoff,^2, Henrik Siegumfeldt,¹ and Birgitte Bjørn Budde^1*

Department of Food Science,¹ Department of Mathematics and Physics, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark²

Received 13 July 2005/ Accepted 29 November 2005

In situ analyses of single Listeria monocytogenes cells at subinhibitory concentrations of leucocin 4010 and nisin revealed two subpopulations when measured by fluorescence ratio imaging microscopy (FRIM) after staining with 5(6)-carboxyfluorescein diacetate succinimidyl ester. One subpopulation consisted of cells with a dissipated pH gradient (pH), and the other consisted of cells that maintained pH. The proportion of cells belonging to each subpopulation was estimated, and the concentrations of bacteriocins required to dissipate pH for 90% of the cell population (ED₉₀) was predicted. ED₉₀ increased after the addition of sodium chloride (1 to 3% [wt/vol]) to the bacteriocin solutions, while ED₉₀ decreased by the addition of sodium nitrite (60 and 100 ppm). Other meat additives, including sodium phosphate, sodium lactate, sodium citrate, and sodium acetate slightly increased ED₉₀. The inhibitory effect of sodium chloride on the antilisterial activity of leucocin 4010 and nisin was confirmed on the surfaces of meat sausages. This study highlights the important practical implications of applying subinhibitory concentrations of bacteriocins, which results in unaffected target cells. In situ analyses by FRIM in combination with modeling of single-cell data can be applied to ensure that sufficient concentrations of bacteriocins are used in food preservation.

---

* Corresponding author. Mailing address: The Royal Veterinary and Agricultural University, Department of Food Science, Rolighedsvej 30, 4th Floor, DK-1958 Frederiksberg C, Denmark. Phone: 45 35 28 32 84. Fax: 45 35 28 32 14. E-mail: bbb{at}kvl.dk.

Present address: Chr. Hansen A/S, Hørsholm, Denmark.

Present address: Technical University of Denmark, Lyngby, Denmark.

---

Applied and Environmental Microbiology, February 2006, p. 1631-1638, Vol. 72, No. 2
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.2.1631-1638.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Kastbjerg, V. G., Nielsen, D. S., Arneborg, N., Gram, L. (2009). Response of Listeria monocytogenes to Disinfection Stress at the Single-Cell and Population Levels as Monitored by Intracellular pH Measurements and Viable-Cell Counts. Appl. Environ. Microbiol. 75: 4550-4556 [Abstract] [Full Text]  
• Rasmussen, M. B., Oddershede, L. B., Siegumfeldt, H. (2008). Optical Tweezers Cause Physiological Damage to Escherichia coli and Listeria Bacteria. Appl. Environ. Microbiol. 74: 2441-2446 [Abstract] [Full Text]