Dependency of hydration and growth conditions on the mechanical properties of oral biofilms

Abstract

Within the oral cavity, dental biofilms experience dynamic environments, in part due to changes in dietary content, frequency of intake and health conditions. This can impact bacterial diversity and morpho-mechanical properties. While phenotypic properties of oral biofilms are closely related to their composition, these can readily change according to dynamic variations in the growth environment and nutrient availability. Understanding the interlink between phenotypic properties, variable growth conditions, and community characterization is an essential requirement to develop structure–property relationships in oral-biofilms. In this study, the impact of two distinct growth media types with increasing richness on the properties of oral biofilms was assessed through a new combination of in-vitro time-lapse biophysical methods with microbiological assays. Oral biofilms grown in the enriched media composition presented a decrease in their pH, an increase in soluble EPS production, and a severe reduction in bacterial diversity. Additionally, enriched media conditions presented an increase in biofilm volumetric changes (upon hydration) as well as a reduction in elastic modulus upon indentation. With hydration time considered a major factor contributing to changes in biofilm mechanical properties, we have shown that it is less associated than media richness. Future investigations can now use this time-lapse approach, with a clearer focus on the extracellular matrix of oral biofilms dictating their morpho-mechanical properties.

Bacterial extracellular polymeric substances as potential saliva substitute

“…In nature, many EPS types are highly hygroscopic and can provide protection against dehydration of microbes in biofilms by keeping moisture in the surrounding of living cells (Costa et al 2018 , Seviour et al 2019 ). Bound water can reach up to 98% of EPS total mass (Pattem et al 2021 ). In a clinical setting, oral biofilms experience dynamic cycles of de- and re-hydration due to fluid consumption (Signoretto et al 2010 ) and saliva stimulation (Thurnheer and Belibasakis 2018 ).…”

A Local Desiccant Antimicrobial Agent as an Alternative to Adjunctive Antibiotics in the Treatment of Periodontitis: A Narrative Review

“…Common oral antiseptics target the inhibition of plaque attachment or bacterial destruction through various mechanisms [ 44 , 50 , 55 , 56 ]. However, most of these products lack the potential to disorganize already-formed biofilms [ 57 ] through the destruction of the extracellular matrix [ 35 , 56 , 58 ], which contributes to the maintenance of a highly hydrated and protective environment for residing bacteria [ 34 , 59 , 60 ].…”