Transcriptional repressor Rex is involved in regulation of oxidative stress response and biofilm formation by Streptococcus mutans

Bitoun, Jacob P.; Nguyen, Anne; Fan, Yuwei; Burne, Robert A.; Wen, Zezhang T.

doi:10.1111/j.1574-6968.2011.02293.x

Cited by 60 publications

(117 citation statements)

References 44 publications

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“…For field emission-scanning electron microscopy (FE-SEM) analysis, Strep. mutans overnight cultures were grown in BMG, BMGS or BMS on HA discs that were placed horizontally in 24-well plates as described elsewhere (Bitoun et al, 2011;Wen & Burne, 2004). After 24 h of growth, the HA discs were removed and washed twice with PBS, pH 7.4, before overnight fixation with 2.5 % glutaraldehyde (Polysciences) at 4 uC.…”

Section: Methodsmentioning

confidence: 99%

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Deficiency of BrpB causes major defects in cell division, stress responses and biofilm formation by Streptococcus mutans

et al. 2014

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Streptococcus mutans, the primary aetiological agent of dental caries, possesses an YjeE-like protein that is encoded by locus SMU.409, herein designated brpB. In this study, a BrpBdeficient mutant, JB409, and a double mutant deficient of BrpB and BrpA (a paralogue of the LytR-CpsA-Psr family of cell wall-associated proteins), JB819, were constructed and characterized using function assays and microscopy analysis. Both JB409 and JB819 displayed extended lag phases and drastically slowed growth rates during growth in brain heart infusion medium as compared to the wild-type, UA159. Relative to UA159, JB409 and JB819 were more than 60-and 10-fold more susceptible to acid killing at pH 2.8, and more than 1 and 2 logs more susceptible to hydrogen peroxide, respectively. Complementation of the deficient mutants with a wild-type copy of the respective gene(s) partly restored the acid and oxidative stress responses to a level similar to the wild-type. As compared to UA159, biofilm formation by JB409 and JB819 was drastically reduced (P,0.001), especially during growth in medium containing sucrose. Under a scanning electron microscope, JB409 had significantly more giant cells with an elongated, rod-like morphology, and JB819 formed marble-like super cells with apparent defects in cell division. As revealed by transmission electron microscopy analysis, BrpB deficiency in both JB409 and JB819 resulted in the development of low electron density patches and formation of a loose nucleoid structure. Taken together, these results suggest that BrpB likely functions together with BrpA in regulating cell envelope biogenesis/homeostasis in Strep. mutans. Further studies are under way to elucidate the mechanism that underlies the BrpA-and BrpB-mediated regulation.

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Section: Methodsmentioning

confidence: 99%

“…The resulting image stacks were analysed using Slidebook 5.0 (Olympus). COMSTAT 2.0 was used to quantify the biovolume, surface area, mean thickness and maximum thickness of the biofilms as described elsewhere (Heydorn et al, 2000;Wen et al, 2011). Biovolume is defined as the biofilm volume (mm 3 ) per unit area (mm 2 ) (Heydorn et al, 2000).…”

Section: Methodsmentioning

confidence: 99%

Deficiency of BrpB causes major defects in cell division, stress responses and biofilm formation by Streptococcus mutans

et al. 2014

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“…However, Rex has been shown to be involved in the oxidative stress response in the related organism Streptococcus mutans (Bitoun et al, 2011). Rex might also play a similar role in lactobacilli.…”

Section: Stress Responsementioning

confidence: 99%

Proteomic and transcriptomic analysis of the response to bile stress of Lactobacillus casei BL23

Alcántara

Zúñiga

2012

Microbiology

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Lactobacillus casei is a lactic acid bacterium commonly found in the gastrointestinal tract of animals, and some strains are used as probiotics. The ability of probiotic strains to survive the passage through the gastrointestinal tract is considered a key factor for their probiotic action. Therefore, tolerance to bile salts is a desirable feature for probiotic strains. In this study we have characterized the response of L. casei BL23 to bile by a transcriptomic and proteomic approach. The analysis revealed that exposure to bile induced changes in the abundance of 52 proteins and the transcript levels of 67 genes. The observed changes affected genes and proteins involved in the stress response, fatty acid and cell wall biosynthesis, metabolism of carbohydrates, transport of peptides, coenzyme levels, membrane H + -ATPase, and a number of uncharacterized genes and proteins. These data provide new insights into the mechanisms that enable L. casei BL23 to cope with bile stress.

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“…Oxidative stress is caused by the presence of strong oxidizers, such as O2 -, H2O2, and methylglyoxal, and is mediated by an array of mediators and response systems 183,[189][190][191] .…”

Section: Oxidative Stress Regulation and Electron Mediationmentioning

confidence: 99%

“…This consequently adds an additional strain on the electron mediation system, requiring the pathway fluxes to adjust. Other response systems, such as the FNR-FNA system, actively change the expression of pathways used for electron sinking in response to the detection of oxidizers in order to directly alter these pathway fluxes 191 . As such, while the oxidative stress regulation systems do not directly respond to changes in electron mediation, they do generate a strong effect on the electron balance of the system, and therefore act as a subset within the electron mediation system as a whole.…”

Section: Oxidative Stress Regulation and Electron Mediationmentioning

confidence: 99%

Metabolic mechanisms and regulation of mixed culture fermentation

Hoelzle¹

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Fermentation of waste streams is an emerging method for production of biofuels and commodity chemicals, and mixed-culture fermentation allows for robustness and flexibility in the range of waste streams that can be processed, and in varying product mix from the fermenter. However, mechanistic models of mixed culture fermentation are limited, with mixed culture fermentation generally resulting in acetate, butyrate, and ethanol, with even these production modes are not clearly understood. Results from pure-culture fermentation, as well as those from methanogenic reactors indicate the possibility to produce high-value lactate and propionate if the cellular mechanisms which control the expression of these production modes can be harnessed and understood. Lactate and propionate are key chemicals in production of bioplastics, pesticides, preservatives, and food additives, among many other uses. Their production by mixed cultures has been observed at high substrate concentrations (shock loads), and inconsistently at high pH. They are produced via metabolic pathways which branch off of the primary energy-generation pathways. In general, they are thought to be produced by microbes as a way to redirect excess carbon flow in transient states, and are also thought to be produced as an electron sink. In this work, both of these possible production influences are explored for steady state production of lactate and propionate.By increasing substrate from limiting to non-limiting quantities, and thereby increasing the carbon load on a fermentation system, lactate production was successfully achieved and maintained during steady state only when substrate was in excess. Substrate consumption at this point was 14.1±0.8 gCOD·L -1 , and lactate accounted for 25±1% of the total product COD. Upon return to substrate-limiting conditions, the process returned to butyrate production. This demonstrates the reversibility of this production mode. Taxonomic analysis via Illumina pyrosequencing of the 16S rRNA gene revealed that the microbial community experienced a shift from Megasphaera-dominant during butyrate production to Ethanoligenens-dominant during lactate production. Taxonomy was also regained upon return to substrate-limiting conditions. However, taxonomy alone could not explain the product shift because Ethanoligenens produces little to no lactate in cultured references. A mechanistic description of the product shift therefore required molecular analysis of the metabolic mechanisms, and this was achieved through metaproteomics via SWATH-MS.The evidence suggests that at high carbon loads, toxic methylglyoxal is formed in many microbe groups, including Megasphaera, due to limited processing capacity of the ii dihydroxyacetone-P intermediate of glycolysis. The methylglyoxal is converted into lactate for disposal. This detoxification need is abated upon return to substrate-limited conditions. The impact of redox stress was examined using cathodic electro-fermentation with soluble mediator chemicals ranging from slightly negati...

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Transcriptional repressor Rex is involved in regulation of oxidative stress response and biofilm formation by Streptococcus mutans

Cited by 60 publications

References 44 publications

Deficiency of BrpB causes major defects in cell division, stress responses and biofilm formation by Streptococcus mutans

Deficiency of BrpB causes major defects in cell division, stress responses and biofilm formation by Streptococcus mutans

Proteomic and transcriptomic analysis of the response to bile stress of Lactobacillus casei BL23

Metabolic mechanisms and regulation of mixed culture fermentation

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