pH Bacteria Research Articles

Study the Role of Ph in Curli Biogenesis Gene Expression in Enterobacter Cloacae Local Isolates

Enterobacter cloacae is the most common pathogenic species of the genus Enterobacter, identified inhospitalized and enfeebled patients as the etiologic agent of many infections and considered as a significantbacterial pathogen in recent years. E. Cloacae are typical gram negative opportunistic forms of bacteria thatcause illness after another infection or injury has influenced the host immune system and are related withnosocomial infections. The infection may be caused by GIT, UTI or cross contamination of the blood. Thepresent study focused on the existence of the main curli biogenesis gene (csgA) and the role of pH as anenvironmental factor in the gene expression (csgA) for curli biogenesis. In this study, urine samples from75 patients.In Baghdad city clinically diagnosed with urinary tract infection,for gram staining, Api20Systemand gene expression (csgA) gene in Standardized pH7 and acid pH4 RT-PCR was performed with specificprimers. Conventional gram staining techniques, agricultural methods and System API 20E showed goodresults for E. Cloacae. For the 75 patients, 10 (13.3%) the findings find the highest gene expression foldvalues for the (csgA)gene in pH7 while the lowest fold value for (csgA) at acid pH4 (0.1577) thus themodify conditions growth such as pH of bacteria E. Cloacae triggers gene expression changes for biogenesisprocess. the findings of rpoB gene expression, which was used as a control gene, indicated that this gene wasgood as a housekeeping gene.

The regulation of intracellular pH in bacteria.

The regulation of intracellular pH (pHi) in bacterial cells is achieved through control over cation (and anion) permeability. In addition to the active components of homeostasis there are contributions from essentially passive elements, such as the lipid composition of the membrane and the buffering capacity of the cytoplasm. Active homeostasis involves control over the movement of K+, Na+ and H+. Alterations in the membrane permeability for any of these cations may cause perturbation of homeostasis. In Escherichia coli this is exemplified by the controlled activation of K+ efflux systems by glutathione adducts leading to temporary acidification of the cytoplasm. This is achieved by sophisticated control over the KefB and KefC systems, and is tightly integrated with glutathione-dependent detoxification mechanisms. Such control over pHi facilitates survival of the cell following exposure to toxic electrophiles. The components of pH homeostasis will be reviewed and the molecular mechanisms, and role of, the KefB and KefC systems will be discussed.

Cation movements at alkaline pH in bacteria growing without respiration.

The respiratory chain has a central role in energy metabolism as a generator of a proton motive force in aerobic bacteria. In contrast, Enterococcus hirae (formerly Streptococcus faecalis), which lacks the respiratory chain, generates this proton gradient via a F-type H+ ATPase, but it works only at a pH below 8; no significant proton motive force is generated at a pH above 8. An Escherichia coli mutant deficient in both the respiratory chain and the H+ ATPase grew with a negligible proton motive force within the wide range of medium pH. It has been suggested that both E. hirae and E. coli are able to grow even when the cytoplasm is alkalinized beyond pH 8. These observations lead to the conclusion that bacteria can survive without operating cation transport systems driven by a proton motive force at alkaline pH. The activity of any transport system with optimum pH around neutrality should decline when both the outside and inside of cells are alkalinized. Thus, changes in transport systems as well as cellular metabolism may be essential for bacterial adaptation to changes in environmental pH.

A Novel Method for Continuous Determination of the Intracellular pH in Bacteria with the Internally Conjugated Fluorescent Probe 5 (and 6-)-Carboxyfluorescein Succinimidyl Ester

A novel method based on the intracellular conjugation of the fluorescent probe 5 (and 6-)-carboxyfluorescein succinimidyl ester (cFSE) was developed to determine the intracellular pH of bacteria. cFSE can be taken up by bacteria in the form of its diacetate ester, 5 (and 6-)-carboxyfluorescein diacetate succinimidyl ester, which is subsequently hydrolyzed by esterases to cFSE in the cytoplasm. When Lactococcus lactis cells were permeabilized with ethanol, a significant proportion of cFSE was retained in the cells, which indicated that cFSE was bound intracellularly. Unbound probe could be conveniently extruded by a short incubation of the cells in the presence of a fermentable sugar, most likely by exploiting an active transport system. Such a transport system for cFSE was identified in L. lactis, Listeria innocua, and Bacillus subtilis. The intracellular pH in bacteria can be determined from the ratio of the fluorescence signal at the pH-sensitive wavelength (490 nm) and the fluorescence signal at the pH-insensitive wavelength (440 nm). This cFSE ratio method significantly reduced problems due to the efflux of fluorescent probe from the cells during the measurement. Moreover, the method described was successfully used to determine the intracellular pH in bacteria under stress conditions, such as elevated temperatures and the presence of detergents.

The application of pH-sensitive fluorescent dyes in lactic acid bacteria reveals distinct extrusion systems for unmodified and conjugated dyes.

Intracellular pH in bacteria can be measured efficiently between internal pH values of 6.5 and 8.5 with the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5[and-6]-carboxyfluorescein (BCECF). A new fluorescent pH probe with a lower pKa(app) than BCECF was synthesized from fluorescein isothiocyanate and glutamate. The new probe, N-(fluorescein thio-ureanyl)-glutamate (FTUG), was much less sensitive to changes in concentrations of KCl than was BCECF. Similar to BCECF, an efflux of FTUG independent of the proton motive force, but dependent on ATP, was observed both in Lactobacillus plantarum and Lactococcus lactis. Corrections for probe efflux allowed accurate measurements of the pHin. Similar intracellular pH values were determined with FTUG and BCECF, in the range where both probes can be applied, and the pH values correlated well with those estimated from the distribution of radio-labelled benzoic acid. Since FITC can easily be coupled to substrates containing an amino group, it is possible to develop other FITC derivatives as well. The mechanisms of probe excretion and the nature of the excreted product(s) were studied in further detail for BCECF and FTUG. BCECF was excreted from wild-type L. lactis in an unmodified form as was determined by chromatographic and mass spectrometry analysis. In the case of FTUG, the excreted product was a conjugated derivative. Unmodified FTUG was not excreted, although it was present in cellular extracts from L. lactis. Exit of BCECF was completely inhibited in a BCECF efflux mutant (Bef-) of L. lactis, whereas FTUG-conjugate efflux in this mutant was similar to the wild-type. Addition of indomethacin, a known inhibitor of BCECF efflux in human epithelial cells, resulted in complete inhibition of BCECF efflux in wild-type L. lactis, whereas FTUG-conjugate exit was only slightly affected. The results of the mutant and inhibitor studies suggest that FTUG-conjugate and BCECF efflux in L. lactis are mediated by different ATP-driven extrusion systems for organic anions.

Regulation of cytoplasmic pH in bacteria.

Regulation of cytoplasmic pH in bacteria.

Regulation of cytoplasmic pH in bacteria.

Regulation of cytoplasmic pH in bacteria.