Gene expression and metabolic activity of Streptococcus mutans during exposure to dietary carbohydrates glucose, sucrose, lactose, and xylitol

Abstract

Recent RNA sequencing studies have given us a deeper insight into the cariogenic impact of carbohydrate sources in the bacterium Streptococcus mutans, the principal microbial agent in dental caries etiopathogenesis. The process of dental caries development is facilitated by the ability of this bacterium to ferment some carbohydrates into organic acids contributing to a pH decrease in the oral cavity and the demineralization of the hard tissues of the tooth. Furthermore, in dental caries progression, biofilm formation, which starts and ends with free planktonic cells, plays an important role and has several unique properties called virulence factors. The most cariogenic carbohydrate is sucrose, an easily metabolizable source of energy that induces the acidification and synthesis of glucans, forming typical bacterial cell clumps. We used multifaceted methodological approaches to compare the transcriptomic and metabolomic profiles of S. mutans growing in planktonic culture on preferred and nonpreferred carbohydrates and in fasting conditions. Streptococcus mutans in a planktonic culture with lactose produced the same pH drop as glucose and sucrose. By contrast, xylitol and lactose showed high effectiveness in regulating intracellular polysaccharide metabolism, cell wall structure, and overall virulence involved in the initial phase of biofilm formation and structure but with an opposite pattern compared with sucrose and glucose. Our results confirmed the recent findings that xylitol and lactose play a vital role in biofilm structure. However, they do not reduce its formation, which is related to the creation of a cariogenic environment.

Quantifying variations associated with dental caries reveals disparity in effect allele frequencies across diverse populations

“…DC is a multifactorial and dynamic condition that causes demineralisation of dental hard tissues [1]. DC is triggered by acid-producing bacteria such as Streptococcus mutans [2] and Lactobacillus [3][4][5]. This production of acid results in the development of tiny cavities, which can progress deeper, affecting the dentin and pulp if left untreated [6,7].…”

Identification of a Novel Lactose-Specific PTS Operon in Bacillus licheniformis and Development of Derivative Artificial Operon Modules

“…The production of lactose metabolic proteins is energy-consuming, so the lactose operon lac gene expression is strictly regulated. The molecular regulation mechanism of lactose metabolism has been studied in detail by Streptococcus mutans and Lacticaseibacillus paracasei. − Aside from the negative regulator LacR, the lac operon is negatively regulated by the catabolite control protein (CcpA), which is a global regulatory factor. When there are preferred carbon sources, such as glucose, the expression of lactose operon in most bacteria is negatively regulated to achieve priority utilization of glucose.…”