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Botanicals and the Gut Microbiome
Published in Namrita Lall, Medicinal Plants for Cosmetics, Health and Diseases, 2022
Quorum sensing is the communication pathway between bacterial species that is based on chemical signals and through which their behavior can be determined. The main signaling molecule is primarily N-acyl homoserine lactones. Quorum sensing controls a number of features within a bacterial colony, such as their resistance, their motility and how they form biofilms, as well as their level of pathogenicity (McCarthy and O’Gara, 2015). Next-generation antimicrobials have the ability to decrease resistance and target the communication between bacteria known as quorum sensing/signaling. Ingested antibiotic adjuvants can increase the oral bioavailability of the antibiotic by inhibiting the quorum sensing between the pathogenic bacteria and making them less virulent and pathogenic, rendering them more susceptible to antibiotics. The gut microbiota mainly disrupts the communication between the pathogenic bacterial colonies and therefore prevents from taking place the initial stages of infection which involve integration within the host (Clemente et al., 2012).
Cell-Cell Communication in Lactic Acid Bacteria
Published in Marcela Albuquerque Cavalcanti de Albuquerque, Alejandra de Moreno de LeBlanc, Jean Guy LeBlanc, Raquel Bedani, Lactic Acid Bacteria, 2020
Emília Maria França Lima, Beatriz Ximena Valencia Quecán, Luciana Rodrigues da Cunha, Bernadette Dora Gombossy de Melo Franco, Uelinton Manoel Pinto
Bacteria can communicate and regulate the expression of several genes according to cell density. This mechanism is a type of communication known as quorum sensing (QS), which is based on the production, secretion, and detection of small signaling molecules, whose concentration correlates with the cell density of microorganisms secreting these molecules in the surroundings (Choudhary and Schmidt-Dannert 2010). All quorum sensing systems usually involve the synthesis of a biomolecule with low molecular weight, also termed autoinducer (AI), which is recognized by the responder cell (Declerck et al. 2007, LaSarre and Federle 2013). As bacterial population density increases, the concentration of autoinducer molecules in the environment also rises (Johansen and Jespersen 2017).
Bacterial Infections of the Oral Cavity
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
P. S. Manoharan, Praveen Rajesh
With evolution, S. mutans has developed a mechanism to compete against other oral species. It has developed defenses against increased oxidative stress and remained resistant to by-products of its own metabolism. Worldwide promotion of toothbrush and flossing have also made considerable modification in oral environment, making resistant biofilms loaded with microorganisms which turn pathogenic. Virulence and pathogenic potential in the recent decades are understood by quorum sensing, which has opened a new avenue for research. The host substrate are the mucosa and the teeth. The mucosa sheds continuously and does not provide a stable home for the microorganisms, whereas the tooth and artificial crown or replacements and restorations can serve as a stable substrate to harbor biofilms, which become more complicated with aforementioned factors.
Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7
Published in Gut Microbes, 2022
Hongmin Sun, Min Wang, Yutao Liu, Pan Wu, Ting Yao, Wen Yang, Qian Yang, Jun Yan, Bin Yang
Quorum sensing is a cell-to-cell signaling system based on the production of hormone-like compounds known as autoinducers (AI),64 which allow bacteria to detect their own population as well as the population of other bacterial species present in the same environment.64 The host-derived stress hormones epinephrine (EPI) and norepinephrine (NE) are autoinducer analogs that are recognized by the quorum sensing system and are involved in the regulation of flagellar-mediated motility in EHEC O157:H7.26,27 The two-fluorophore chemotaxis assay showed a concentration-dependent migration of EHEC O157:H7 toward EPI and NE.27 Furthermore, addition of 50 µM EPI or NE to motility agar plates significantly increased EHEC O157:H7 motility, compared to that in the untreated control.27 The regulation of EHEC O157:H7 motility by EPI/NE is mediated by the two-component regulatory system QseBC,26 which will be discussed later in the review.
Adjunctive probiotics after periodontal debridement versus placebo: a systematic review and meta-analysis
Published in Acta Odontologica Scandinavica, 2022
Ethan Ng, John Rong Hao Tay, Seyed Ehsan Saffari, Lum Peng Lim, Kong Mun Chung, Marianne Meng Ann Ong
Probiotics may also act via signaling interference. Quorum sensing is the process by which bacteria produce and detect signal molecules to coordinate their behavior [21]. An example is the accessory gene regulator (agr) quorum sensing system used by Staphylococcus aureus which is important for up-regulation of virulence factors during infection and the development of acute disease [22]. An in vitro study demonstrated that signaling molecules produced by Lactobacillus reuteri have the potential to interfere with this quorum-sensing system within S. aureus, resulting in decreased production of virulence factors [23]. More recently, a human study demonstrated that probiotic Bacillus was able to block this signaling system, thus reducing the infectivity of S. aureus infections [24]. While these actions have not yet been described in the dental literature, quorum-sensing regulation appears to be a valid mechanism for further research.
Quorum quenching enzymes and their effects on virulence, biofilm, and microbiomes: a review of recent advances
Published in Expert Review of Anti-infective Therapy, 2020
We have discussed the nature and key roles of main quorum sensing (QS) circuits and signals in regulating bacterial behaviors including pathogenicity and biofilm formation, in this review. Recent efforts have demonstrated the variety of QS interference strategies, and the numerous enzymatic ways to inactivate signaling molecules. Such enzymes, through the interference in QS, can effectively behave as biofilm and virulence inhibitors. This and their lack of cytotoxicity are making them appealing candidates to control bacteria. Several studies have highlighted their potential to prevent bacterial infections in a variety of in vivo systems. The identification of highly stable enzymes from extremophiles, and the improvement of their properties via molecular engineering may open the path for the use of the QS interference strategy in a variety of clinical settings.