Energy conservation in acidophilic bacteria.

Cobley, J G; Cox, J C

doi:10.1128/mmbr.47.4.579-595.1983

Cited by 55 publications

(27 citation statements)

References 85 publications

(157 reference statements)

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“…According to pre-estimation of 4 days batch cultivation for our strain under various pH values and Fe(II) concentrations, the optimum pH and Fe(II) concentration were determined to be 2.0-3.5 and 150 mM, respectively. These value seemed appropriate in comparison with values reported previously (Barron and Lueking, 1990;Cobley and Cox, 1983;Jones and Kelly, 1983;Kovrov et al, 1978). Since Fe precipitation needs to be minimized during electrochemical cultivation, a pH value of 2.0 was selected as optimal for the medium during electrochemical cultivation.…”

Section: Optimization Of Culture Conditionssupporting

confidence: 81%

Extension of logarithmic growth of Thiobacillus ferrooxidans by potential controlled electrochemical reduction of Fe(III)

Matsumoto

Nakasono

Ohmura

et al. 1999

Biotechnol. Bioeng.

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In this study, we demonstrated that the period of logarithmic growth for Thiobacillus ferrooxidans could be extended when optimal conditions for cell growth were maintained using potential controlled electrochemical cultivation with sufficient aeration. The optimal pH and Fe(II) concentration for the electrolytic cultivation were determined to be 2.0 and 150 mM, respectively. When the potential was set to 0.0V vs Ag/AgCl, the Pt electrode reduced Fe(III) to Fe(II) with an efficiency of 95%. A porous glass microbubble generator was used to maintain adequate levels of dissolved oxygen, which was the electron acceptor for T. ferrooxidans when the cell density in the medium was high. Under these conditions, cells at an initial density of 10(7) cells/mL grew logarithmically for 4days until the cell density was 4 x 10(9) cells/mL. This corresponded to a period of logarithmic growth that was 3 times longer than was observed in batch cultures without electrolysis. In addition, the final cell density reached 10(10) cells/mL after 6 days of electrochemical cultivation, which was a 50-fold increase over conventional batch culture. Under conditions of increasing cell density, potentiostatic electrolysis made it possible to remove Fe(III), which causes product inhibition, at an increasing rate and to correspondingly increase the production rate of Fe(II), which is the electron donor for T. ferrooxidans. Thus, our cultivation system provides a sufficient supply of electron donor and acceptor for T. ferrooxidans, thereby elongating the period of logarithmic growth and producing very high cell densities.

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Section: Optimization Of Culture Conditionssupporting

confidence: 81%

Extension of logarithmic growth of Thiobacillus ferrooxidans by potential controlled electrochemical reduction of Fe(III)

Matsumoto

Nakasono

Ohmura

et al. 1999

Biotechnol. Bioeng.

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“…The Ap and its response to acidic media are quite different in aerobic acidophiles than in acid-tolerant anaerobes, such as the lactobacilli. Respiring acidophiles maintain a large A p, typical of neutrophilic aerobes, consisting of a large A pH at pHo as low as pH 2, and a small A+ [30,33,34]. The cytoplasmic pH is thus maintained at approximately 6.5.…”

Section: Bioenergeticsmentioning

confidence: 99%

“…In clostridia [46,58,61,62], many streptococci [55,35,41,38], and lactobacilli (see above), as the pH o decreases because of the accumulation of acidic fermentation end-products, the pH i also decreases, although it remains more alkahne than the pHo; i.e., the cells maintain a A pH, alkahne inside. Thus, unlike many aerobes [30,34], the anaerobic fermenters tolerate fairly wide variations in internal proton concentration. It is not clear whether these cells regulated the pH i in the sense of possessing systems that respond to perturbations in pH i and restore the pH i to the original value [31].…”

Section: Regulation Of Cytoplasmic Phmentioning

confidence: 99%

Bioenergetics of lactic acid bacteria: cytoplasmic pH and osmotolerance

Kashket¹

1987

FEMS Microbiology Letters

350

209

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Lactic acid bacteria maintain a cytoplasm that is more alkaline than the medium, but whose pH decreases as the medium is acidified during growth and fermentation. Streptococci generally acidify the cytoplasm from approximately pH 7.6 to 5.7 (external pH 4.5) before growth and then fermentation cease. The internal enzyme machinery of these anaerobic fermenters thus tolerates a fairly wide range in internal proton concentration. Lactobacilli tolerate a significantly more acidic cytoplasmic pH of 4.4 (external pH 3.5). However, when the cytoplasmic pH decreases below a threshold pH, which depends on the organism cellular functions are inhibited. Fermentation end‐products, such as organic acids or alcohols, exert their deleterious effects by bringing about acidification of the cytoplasm below the permissible pH. Organic acids, which act as protonophores, or solvents, which perturb membrane phospholipids, at high concentrations increase the inward leak of H+ so that H+ efflux is not rapid enough to alkalinize the cytoplasm. The membrane pH gradient is thus dissipated. A specific strain of Lactobacillus acidophilus has been found to be unusually osmotolerant. The osmoresistance is due to the cells' capacity to accumulate glycine betaine by a transport carrier that is activated, but not induced, by high medium osmotic pressure.

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“…However, in one case [10], this appears to be an assumption rather than a conclusion. As is pointed out by Cobley and Cox [22], these workers used 2,4-dinitrophenol (DNP)-treated cells to determine the extent of non-specific probe-binding. In other words, they assumed a priori that whatever amount of the probe accumulated in such cells was due to non-specific binding and not to any possible residual ApH.…”

Section: Effects Of Protonophores and Other Ionophoresmentioning

confidence: 99%

Keeping a neutral cytoplasm; the bioenergetics of obligate acidophiles

Matin

1990

FEMS Microbiology Letters

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Energy conservation in acidophilic bacteria.

Cited by 55 publications

References 85 publications

Extension of logarithmic growth of Thiobacillus ferrooxidans by potential controlled electrochemical reduction of Fe(III)

Extension of logarithmic growth of Thiobacillus ferrooxidans by potential controlled electrochemical reduction of Fe(III)

Bioenergetics of lactic acid bacteria: cytoplasmic pH and osmotolerance

Keeping a neutral cytoplasm; the bioenergetics of obligate acidophiles

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