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Titolo:
The intracellular pH of the thermophilic bacterium Thermoanaerobacter wiegelii during growth and production of fermentation acids
Autore:
Cook, GM;
Indirizzi:
Univ Otago, Otago Sch Med Sci, Dept Microbiol, Dunedin, New Zealand Univ Otago Dunedin New Zealand ci, Dept Microbiol, Dunedin, New Zealand
Titolo Testata:
EXTREMOPHILES
fascicolo: 5, volume: 4, anno: 2000,
pagine: 279 - 284
SICI:
1431-0651(200010)4:5<279:TIPOTT>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
CLOSTRIDIUM-THERMOCELLUM; ACETIC-ACID; INTERNAL-PH; ALKALOPHILIC BACTERIA; STREPTOCOCCUS-BOVIS; ANION ACCUMULATION; ETHANOL-PRODUCTION; EXTRACELLULAR PH; RUMINAL BACTERIA; CYTOPLASMIC PH;
Keywords:
thermophile; pH regulation; fermentation acids; bioenergetics;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Cook, GM Univ Otago, Otago Sch Med Sci, Dept Microbiol, POB 56, Dunedin, New Zealand Univ Otago POB 56 Dunedin New Zealand 56, Dunedin, New Zealand
Citazione:
G.M. Cook, "The intracellular pH of the thermophilic bacterium Thermoanaerobacter wiegelii during growth and production of fermentation acids", EXTREMOPHIL, 4(5), 2000, pp. 279-284

Abstract

The thermophilic glycolytic anaerobe Thermoanaerobacter wiegelii grows over the pH range 5.1-7.7, and no growth is observed below pH 5.0 or above 7.7. When T. wiegelii was grown in pH-uncontrolled batch culture, glucose was fermented to ethanol, acetate, and lactate. Small amounts of lactic acid were produced once the external pH reached 6.0, and a fructose-1,6-diphosphate (FDP) activated lactate dehydrogenase (LDH) was detected in cell-free crude extracts. Maximal activation of LDH by FDP was observed at pH 6.2. As the pH of the medium declined from 6.7 to 5.1 due to the production of acetate and lactate, the total protonmotive force (Deltap) remained between -110 and -130mV, and the membrane potential (Delta Psi) decreased from -104 to -65mV. This decrease in Delta Psi was paralleled by an increase in the chemical gradient of protons (Z Delta pH) from -31 to -62mV at pH 5.1. Based on these results, T. wiegelii maintained a small Delta pH (0.3-0.9 units, inside alkaline) as the medium pH declined and interconverted Delta Psi to Z Delta pH to maintain the total ap relatively constant. Intracellular potassium decreased from 150 mM at pH 6.70 to 50 mM at pH 5.1, and this representeda 33-mV decline in the transmembrane chemical potential of potassium. The ability to synthesize ATP remained constant as the external pH declined, and therefore metabolic energy per se was not a critical aspect of pH sensitivity.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/04/20 alle ore 08:19:20