The quorum-sensing system links metabolism to virulence, in part by increasing bacterial survival during exposure to lethal concentrations of HO, a crucial host defense against . We now report that protection by surprisingly extends beyond post-exponential growth to the exit from stationary phase when the system is no longer turned on. Thus, can be considered a constitutive protective factor. Deletion of increased both respiration and fermentation but decreased ATP levels and growth, suggesting that Δ cells assume a hyperactive metabolic state in response to reduced metabolic efficiency. As expected from increased respiratory gene expression, reactive oxygen species (ROS) accumulated more in the mutant than in wild-type cells, thereby explaining elevated susceptibility of Δ strains to lethal HO doses. Increased survival of wild-type cells during HO exposure required , which detoxifies superoxide. Additionally, pretreatment of with respiration-reducing menadione protected Δ cells from killing by HO. Thus, genetic deletion and pharmacologic experiments indicate that helps control endogenous ROS, thereby providing resilience against exogenous ROS. The long-lived "memory" of -mediated protection, which is uncoupled from activation kinetics, increased hematogenous dissemination to certain tissues during sepsis in ROS-producing, wild-type mice but not ROS-deficient (Nox2) mice. These results demonstrate the importance of protection that anticipates impending ROS-mediated immune attack. The ubiquity of quorum sensing suggests that it protects many bacterial species from oxidative damage.
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http://dx.doi.org/10.1101/2023.06.08.544038 | DOI Listing |
Can J Infect Dis Med Microbiol
December 2024
Department of Applied Health Sciences, School of Health Sciences, Kisii University, Kisii, Kenya.
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View Article and Find Full Text PDFBiochem Mol Biol Educ
December 2024
Chemistry Department, Faculty of Sciences, University of Beira Interior, Covilhã, Portugal.
Bacteria have developed a cell-to-cell communication system called quorum sensing (QS), allowing them to regulate group behavior and synchronize the expression of virulence factors, responsible for increasing their infection capacity and resistance to antimicrobials. Although the control of microbial infections through the inhibition of microbial growth has traditionally been the basis of antimicrobial chemotherapy, the emergence of antimicrobial resistance has led to the search for new microbial control strategies, namely through the inhibition of QS. Among the agents studied to inhibit this bacterial communication are essential oils (EO), which are considered very effective QS inhibitors.
View Article and Find Full Text PDFArch Microbiol
December 2024
Global Leadership School, Handong Global University, Pohang, 37554, South Korea.
Microcystin-LRs (MC-LR) produced by harmful cyanobacterial blooms (HCBs) pose significant hepatotoxic risks to both the environment and public health. Despite the identification and characterization of a limited number of MC-LR degrading bacteria, the challenge of safely removing MC-LRs from freshwater systems without disrupting aquatic ecosystems remains substantial. This study focused on the isolation of lactic acid bacteria from Bapshikhe, a traditional Korean fermented food, and investigated the mechanisms underlying the degradation of MC-LRs by these bacteria.
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