Buffering capacity and H membrane conductance of Gram-negative bacteria

Rius, Núria; Solé, Montserrat; Francia, Alicia; Lorén, J. Gaspar

doi:10.1016/0378-1097(95)00191-7

Cited by 14 publications

(15 citation statements)

References 15 publications

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“…Gross estimates based on Ohm's law indicated that the resistance of the cell membrane to protons declined as protonmotive force increased, allowing faster rates of ATP hydrolysis and proton pumping. However, proton flux rates predicted by these calculations were 20-50-fold faster than values previously measured in bacteria (Maloney, 1979 ;Rius & Lore! n, 1998 ;Rius et al, 1994 ;Bender et al, 1986).…”

Section: Introductionmentioning

confidence: 56%

“…Other lactic acid bacteria had non-growth ATP hydrolysis at rates comparable to those estimated for S. bovis (Rosenberger & Elsden, 1960 ;Fordyce et al, 1984), but direct measurements of proton conductance could not explain these high rates of ATP turnover (Maloney, 1979 ;Rius & Lore! n, 1998 ;Rius et al, 1994 ;Bender et al, 1986).…”

Section: Discussionmentioning

confidence: 96%

“…In order for ATP hydrolysis to continue, protonmotive force must continually be dissipated via proton conductance across the cell membrane. Reported values of ' passive ' proton conductance in Gram-positive species are less than 1 mmol H + (g protein) −" h −" (Maloney, 1979 ;Rius & Lore! n, 1998 ;Rius et al, 1994 ;Bender et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

“…Converting rates of pH change to rates of proton flux is dependent on an estimate of cellular buffering capacity, and while literature values for lactic acid bacteria average approximately 200 nmol H + (mg protein) −" per pH unit over an internal pH of 7 to 8, values vary from 50 to at least 350 nmol H + (mg protein) −" per pH unit (Maloney, 1979 ;Rius et al, 1994 ;Rius & Lore! n, 1998).…”

Section: Discussionmentioning

confidence: 99%

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Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion

Bond

Russell

2000

Microbiology

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Section: Introductionmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion

Bond

Russell

2000

Microbiology

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“…While an increase in proton permeability as observed for thermophilic bacilli (1) could provide a plausible explanation for the lowered ⌬pH values, this remains to be experimentally proven with thermophilic alkaliphiles. It should be noted that the proton permeability of the alkaliphile B. alcalophilus is comparable to that of neutrophilic bacteria (23). Moreover, alkaliphilic bacilli have been shown to have appreciable amounts of squalene, squalene derivatives, and C 40 isoprenoids among their neutral membrane lipids, which may prevent proton leakage (2).…”

Section: Resultsmentioning

confidence: 99%

Bioenergetic Properties of the Thermoalkaliphilic Bacillus sp. Strain TA2.A1

et al. 2003

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The thermoalkaliphilic Bacillus sp. strain TA2.A1 was able to grow in pH-controlled batch culture containing a nonfermentable growth substrate from pH 7.5 to 10.0 with no significant change in its specific growth rate, demonstrating that this bacterium is a facultative alkaliphile. Growth at pH 10.0 was sensitive to the protonophore carbonyl cyanide m-chlorophenylhydrazone, suggesting that a proton motive force (⌬p) generated via aerobic respiration was an obligate requirement for growth of strain TA2.A1. Strain TA2.A1 exhibited intracellular pH homeostasis as the external pH increased from 7.5 to 10.0; however, the maximum ⌬pH generated over this pH range was only 1.1 units at an external pH of 9.5. The membrane potential (⌬ ) was maintained between ؊114 mV and ؊150 mV, and little significant change was observed over the pH range for growth. In contrast, the ⌬p declined from ؊164 mV at pH 7.5 to approximately ؊78 mV at pH 10.0. An inwardly directed sodium motive force (⌬pNa ؉ ) of ؊100 mV at pH 10.0 indicated that cellular processes (i.e., solute transport) dependent on a sodium gradient would not be affected by the adverse ⌬p. The phosphorylation potential of strain TA2.A1 was maintained between ؊300 mV and ؊418 mV, and the calculated H ؉ /ATP stoichiometry of the ATP synthase increased from 2.0 at pH 7.5 to 5.7 at pH 10.0. Based on these data, vigorous growth of strain TA2.A1 correlated well with the ⌬pNa ؉ , phosphorylation potential, and the ATP/ADP ratio, but not with ⌬p. This communication represents the first report on the bioenergetics of an extremely thermoalkaliphilic aerobic bacterium.The exploration of extreme environments has led to the isolation of microorganisms that are capable of surviving and growing under extreme conditions. One group of microorganisms that thrive at extremes of high pH are the alkaliphiles. Alkaliphilic bacteria grow over the pH range from 7.5 to 11.5 and can be divided into two groups, obligate alkaliphiles (e.g., Bacillus alcalophilus), which grow between pH 9.0 and pH 11.5, and facultative alkaliphiles (e.g., Bacillus pseudofirmus OF4), which grow between pH 7.5 and 11.2 (11). The intracellular pH of alkaliphilic bacteria is maintained at values more acidic (i.e., approximately 2 pH units) than their external environment (11,12).Because the total proton motive force (⌬p) is the sum of the membrane potential (⌬ ; positive out) and the pH gradient (⌬pH; acid out in neutrophiles), a large ⌬pH generated in the opposite direction results in suboptimal ⌬p values for ATP synthesis (10-12). Despite the low ⌬p, ATP synthesis by the membrane-bound ATP synthase in these bacteria is still coupled to protons (7,8).The isolation of bacteria that can grow at extremes of temperature and high pH (i.e., thermoalkaliphiles) has been described, but these are predominantly anaerobic bacteria (30). To our knowledge, no bacteria that are able to grow at extremes of alkaline pH and temperature under aerobic growth conditions have been reported. We recently isolated a Bacillus species, designated...

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Measurement of fast dynamic intracellular pH in Saccharomyces cerevisiae using benzoic acid pulse

Kresnowati

Suarez-Mendez

Groothuizen

et al. 2006

Biotech & Bioengineering

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pH affects many processes on cell metabolism, such as enzyme kinetics. To enhance the understanding of the living cells, it is therefore indispensable to have a method to monitor the pH in living cells. To accomplish this, a dynamic intracellular pH measurement method applying low concentration benzoic acid pulse was developed. The method was thoroughly validated and successfully implemented for measuring fast dynamic intracellular pH of Saccharomyces cerevisiae in response to a glucose pulse perturbation performed in the BioSCOPE set-up. Fast drop in intracellular pH followed by partial alkalinization was observed following the pulse. The low concentration benzoic acid pulse which was implemented in the method avoids the undesirable effects that may be introduced by benzoic acid to cell metabolism.

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Buffering capacity and H membrane conductance of Gram-negative bacteria

Cited by 14 publications

References 15 publications

Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion

Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion

Bioenergetic Properties of the Thermoalkaliphilic Bacillus sp. Strain TA2.A1

Measurement of fast dynamic intracellular pH in Saccharomyces cerevisiae using benzoic acid pulse

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