Effects of Tween 80 on Growth and Biofilm Formation in Laboratory Media

Abstract

Tween 80 is a widely used non-ionic emulsifier that is added to cosmetics, pharmaceuticals, and foods. Because of its widespread use we need to understand how it affects bacteria on our skin, in our gut, and in food products. The aim of this study is to investigate how Tween 80 affects the growth and antimicrobial susceptibility of Staphylococcus aureus, Listeria monocytogenes, and Pseudomonas fluorescens, which are common causes of spoilage and foodborne illnesses. Addition of 0.1% Tween 80 to laboratory growth media increased the growth rate of planktonic S. aureus batch cultures, and it also increased the total biomass when S. aureus was grown as biofilms. In contrast, Tween 80 had no effect on batch cultures of L. monocytogenes, it slowed the growth rate of P. fluorescens, and it led to formation of less biofilm by both L. monocytogenes and P. fluorescens. Furthermore, Tween 80 lowered the antibacterial efficacy of two hydrophobic antimicrobials: rifampicin and the essential oil isoeugenol. Our findings underline the importance of documenting indirect effects of emulsifiers when studying the efficacy of hydrophobic antimicrobials that are dispersed in solution by emulsification, or when antimicrobials are applied in food matrixes that include emulsifiers. Furthermore, the species-specific effects on microbial growth suggests that Tween 80 in cosmetics and food products could affect the composition of skin and gut microbiota, and the effect of emulsifiers on the human microbiome should therefore be explored to uncover potential health effects.

Improved Assays to Identify the Antibiotic Effects on Planktonic and Sessile Bacteria Using the Example of 1.8-Cineol

“…Furthermore, we could observe that Tween 20 is able to stimulate the bacterial growth at low concentrations (Supplementary Figure S4A). Even though, we could not observe this effect for Tween 80, Nielsen and co-workers found that 0.1% of Tween 80 increases the growth rate of planktonic S. aureus and its biomass, if grown as biofilms [41]. The surfactant may affect the nutrient availability by stressing the cells and thereby facilitating a higher nutritional uptake from the culture media [42].…”

“…More importantly, we observed Tween 80 and Tween 20 to enable planktonic bacterial growth in attendance of 5 mg/ ml 1.8-cineol (Supplementary Figure S4). It is known that Tween 80 can reduce the efficacy of hydrophobic substances probably by enclosing the hydrophobic antibacterial agent into micelles (Interactions between components of the essential oil of Melaleuca alternifolia) [41,42]. Considering our data we would recommend to spare the usage of these emulsifiers while investigating the antimicrobial activity of 1.8-cineol or other hydrophobic substances to prevent artefacts.…”

Optimization of a chitosan solution as potential carrier for the incorporation of Santolina chamaecyparissus L. solid by-product in an edible vegetal coating on ‘Manchego’ cheese

“…The chitosan solution was prepared based on Martins, Cerqueira, and Vicente (2012), with some modifications. Tween 20 was used instead of Tween 80 due to the possibility of microbial growth in the presence of such surfactant (Nielsen, Kjems, Mygind, Snabe, & Meyer, 2016). The addition of glycerol was considered to enhance the plasticizing properties of coatings containing Tween 20 (Ziani, Oses, Coma, & Maté, 2008).…”

The probiotic, Leuconostoc mesenteroides, inhibits Listeria monocytogenes biofilm formation

“…There was 5 μg/ml residual Tween 80 biosurfactant in the coculture originating from the overnight probiotic culture. It is possible that Tween 80 inhibits bacterial biofilm formation (Nielsen, Kjems, Mygind, Snabe, & Meyer, 2016); thus, an L. monocytogenes biofilm formation experiment in BHI medium containing different concentrations of Tween 80 was performed ( Figure S5). Although a high concentration of Tween 80 (100 μg/ml) decreased the biofilm population of both Listeria strains, low concentrations (1-20 μg/ml) that include our residual Tween 80 concentration (5 μg/ml) resulted in very little biofilm inhibition.…”