Investigation of the physiology and architecture of Salmonella Enteritidis biofilms under alkaline conditions

Papakonstantinou, Aikaterina; Efthimiou, Georgios

Abstract

Formation of bacterial biοfilms is an important survival strategy in multiple adverse environments. It is often affected by the nature of the attachment surface, the bacterial strain and the surrounding physicochemical conditions. The effect of low pH on biofilm formation has been well studied, in contrast to the alkaline range. The aim of this project was tο study the effect of alkaline stress on the formation οf biοfilm by Salmonella enteritidis and to examine the biofilm architecture patterns under different conditions, by use of confocal microscopy. The optimal pH for Salmonella biofilm formation was found to be pH 7.0, while pH 10.0 (adjusted by use of sodium hydroxide) reduces it significantly (p-value = 0.015). Planktonic cell growth was hindered due to the alkaline pH, yet the number of viable cells remained high. In addition, the effect on biofilm formation was stronger when the alkaline stimulus was applied during stationary phase (9 h after inoculation). When the pH was adjusted to 10 by use of a commercial alkaline detergent (sodium carbonate or washing soda) similar results were observed. Finally, the biofilm architecture at pH 7.0 was characterized by small cell clusters, whereas at pH 10.0 a slightly thinner layer of individual cells was observed. These findings indicate that although most cells survive the alkaline stress, their ability to form biofilm is impaired at alkaline pH, potentially leading to new disinfectant strategies involving alkaline reagents.

• Journal Article Type: Article
• Publication Date: Feb 8, 2020
• Journal: Acta Scientific Microbiology
• Electronic ISSN: 2581-3226
• Publisher: Acta Scientific
• Peer Reviewed: Peer Reviewed
• Volume: 3
• Issue: 3
• Pages: 1-11
• APA6 Citation: Papakonstantinou, A., & Efthimiou, G. (2020). Investigation of the physiology and architecture of Salmonella Enteritidis biofilms under alkaline conditions. Acta Scientific Microbiology, 3(3), 1-11
• Keywords: Salmonella enteritidis; Biofilm; Alkaline; Architecture; Detergents