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Evaluation on the responses of succinate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-phosphate dehydrogenase to acid shock generated acid tolerance in Escherichia coli.

Jain PK, Jain V, Singh AK, Chauhan A, Sinha S - Adv Biomed Res (2013)

Bottom Line: When challenged by low pH, protons enter the cytoplasm; as a result, mechanisms are required to alleviate the effects of lowered cytoplasmic pH.The activities of Succinate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-phosphate dehydrogenase in acid shocked cells of E. coli DH5 α and E. coli W3110 subjected to pH 3, 4, and 5 by two types of acidification, like external (using 0.1 N HCl), external along with the monensin (1 μM) and cytoplasmic acidification using the sodium benzoate as an acid permeant (20 mM) which is coupled to the electron transport chain by the reducing power, as yet another system possessed by E. coli as an armor against harsh acidic environments.Results showed that an exposure to acidic environment (pH 3, 4 and 5) for a short period of time increased the activities of these dehydrogenases in all types of acidification except cytoplasmic acidification, which shows that higher recycling of reducing power results in pumping out of protons from the cytoplasm through the electron transport chain complexes, thereby restoring the cytoplasmic pH of the bacteria in the range of 7.4-7.8.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Allen Career Institute, Kota, India.

ABSTRACT

Background: Escherichia coli have an optimum pH range of 6-7 for growth and survival that's why, called neutrophiles. The ΔpH across the cytoplasmic membrane is linked to cellular bioenergetics and metabolism of the body which is the major supplier of the proton motive force, so homeostasis of cellular pH is essential. When challenged by low pH, protons enter the cytoplasm; as a result, mechanisms are required to alleviate the effects of lowered cytoplasmic pH.

Materials and methods: The activities of Succinate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-phosphate dehydrogenase in acid shocked cells of E. coli DH5 α and E. coli W3110 subjected to pH 3, 4, and 5 by two types of acidification, like external (using 0.1 N HCl), external along with the monensin (1 μM) and cytoplasmic acidification using the sodium benzoate as an acid permeant (20 mM) which is coupled to the electron transport chain by the reducing power, as yet another system possessed by E. coli as an armor against harsh acidic environments.

Result: Results showed that an exposure to acidic environment (pH 3, 4 and 5) for a short period of time increased the activities of these dehydrogenases in all types of acidification except cytoplasmic acidification, which shows that higher recycling of reducing power results in pumping out of protons from the cytoplasm through the electron transport chain complexes, thereby restoring the cytoplasmic pH of the bacteria in the range of 7.4-7.8.

Conclusion: Study indicates that acid shocked E. coli for a period of 2 h can survive for a sustained period.

No MeSH data available.


Related in: MedlinePlus

Comparison of specific activity of (a) SDH, (b) ICD, (c) MDH, (d) G6PD from internal acidification of E. coli W3100 for different time periods upon exposure to different low pH (acidic shock) using sodium benzoate as an acid permeant (20 mM). pH 7 was used as control (Mean ± SD for triplicate values)
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Figure 6: Comparison of specific activity of (a) SDH, (b) ICD, (c) MDH, (d) G6PD from internal acidification of E. coli W3100 for different time periods upon exposure to different low pH (acidic shock) using sodium benzoate as an acid permeant (20 mM). pH 7 was used as control (Mean ± SD for triplicate values)

Mentions: In the gastrointestinal tract, enteric bacteria are subjected to acid stress from strong acid (HCl) as well as bacterial fermentation products such as acetic, propionic, and butyric acids, which are membrane-permeant weak acids.[923] The cytoplasm of E. coli may be acidified without changing the external pH, for example, by addition of membrane permeant weak acid like sodium benzoate, which is used as a food preservative. The action of sodium benzoate is dependent on the pH value which involves diffusion of the lipophilic, undissociated acid molecule through the plasma membrane into the cytoplasm where it dissociates into charged anions and protons resulting in cytoplasmic acidification. A fall by two to three folds in the specific activities of all four dehydrogenases was observed as a consequence of cytoplasmic acidification in E. coli, which suggesting that these enzymes may have an optimum pH range of near neutral to alkaline [Figures 5 and 6].


Evaluation on the responses of succinate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-phosphate dehydrogenase to acid shock generated acid tolerance in Escherichia coli.

Jain PK, Jain V, Singh AK, Chauhan A, Sinha S - Adv Biomed Res (2013)

Comparison of specific activity of (a) SDH, (b) ICD, (c) MDH, (d) G6PD from internal acidification of E. coli W3100 for different time periods upon exposure to different low pH (acidic shock) using sodium benzoate as an acid permeant (20 mM). pH 7 was used as control (Mean ± SD for triplicate values)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814565&req=5

Figure 6: Comparison of specific activity of (a) SDH, (b) ICD, (c) MDH, (d) G6PD from internal acidification of E. coli W3100 for different time periods upon exposure to different low pH (acidic shock) using sodium benzoate as an acid permeant (20 mM). pH 7 was used as control (Mean ± SD for triplicate values)
Mentions: In the gastrointestinal tract, enteric bacteria are subjected to acid stress from strong acid (HCl) as well as bacterial fermentation products such as acetic, propionic, and butyric acids, which are membrane-permeant weak acids.[923] The cytoplasm of E. coli may be acidified without changing the external pH, for example, by addition of membrane permeant weak acid like sodium benzoate, which is used as a food preservative. The action of sodium benzoate is dependent on the pH value which involves diffusion of the lipophilic, undissociated acid molecule through the plasma membrane into the cytoplasm where it dissociates into charged anions and protons resulting in cytoplasmic acidification. A fall by two to three folds in the specific activities of all four dehydrogenases was observed as a consequence of cytoplasmic acidification in E. coli, which suggesting that these enzymes may have an optimum pH range of near neutral to alkaline [Figures 5 and 6].

Bottom Line: When challenged by low pH, protons enter the cytoplasm; as a result, mechanisms are required to alleviate the effects of lowered cytoplasmic pH.The activities of Succinate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-phosphate dehydrogenase in acid shocked cells of E. coli DH5 α and E. coli W3110 subjected to pH 3, 4, and 5 by two types of acidification, like external (using 0.1 N HCl), external along with the monensin (1 μM) and cytoplasmic acidification using the sodium benzoate as an acid permeant (20 mM) which is coupled to the electron transport chain by the reducing power, as yet another system possessed by E. coli as an armor against harsh acidic environments.Results showed that an exposure to acidic environment (pH 3, 4 and 5) for a short period of time increased the activities of these dehydrogenases in all types of acidification except cytoplasmic acidification, which shows that higher recycling of reducing power results in pumping out of protons from the cytoplasm through the electron transport chain complexes, thereby restoring the cytoplasmic pH of the bacteria in the range of 7.4-7.8.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Allen Career Institute, Kota, India.

ABSTRACT

Background: Escherichia coli have an optimum pH range of 6-7 for growth and survival that's why, called neutrophiles. The ΔpH across the cytoplasmic membrane is linked to cellular bioenergetics and metabolism of the body which is the major supplier of the proton motive force, so homeostasis of cellular pH is essential. When challenged by low pH, protons enter the cytoplasm; as a result, mechanisms are required to alleviate the effects of lowered cytoplasmic pH.

Materials and methods: The activities of Succinate dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-phosphate dehydrogenase in acid shocked cells of E. coli DH5 α and E. coli W3110 subjected to pH 3, 4, and 5 by two types of acidification, like external (using 0.1 N HCl), external along with the monensin (1 μM) and cytoplasmic acidification using the sodium benzoate as an acid permeant (20 mM) which is coupled to the electron transport chain by the reducing power, as yet another system possessed by E. coli as an armor against harsh acidic environments.

Result: Results showed that an exposure to acidic environment (pH 3, 4 and 5) for a short period of time increased the activities of these dehydrogenases in all types of acidification except cytoplasmic acidification, which shows that higher recycling of reducing power results in pumping out of protons from the cytoplasm through the electron transport chain complexes, thereby restoring the cytoplasmic pH of the bacteria in the range of 7.4-7.8.

Conclusion: Study indicates that acid shocked E. coli for a period of 2 h can survive for a sustained period.

No MeSH data available.


Related in: MedlinePlus