Potassium extrusion by the moderately halophilic and alkaliphilic methanogen methanolobus taylorii GS-16 and homeostasis of cytosolic pH

Ni, Shuisong; Boone, Jane E.; Boone, David R.

doi:10.1128/jb.176.23.7274-7279.1994

Cited by 9 publications

(8 citation statements)

References 46 publications

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“…Many other workers have described facultative alkaliphilic bacteria (Steele et al, 1992;Yasmin and Hasnain, 1993a, b, 1997) from saline habitats. Moderately halophilic and alkaliphilic methanogens which could grow over a wide pH range from 6.8-9 were also reported by Ni et al (1994). The strains described here were sensitive to Sm, Tc, Ap and Cm and were resistant to Km.…”

Section: Discussionsupporting

confidence: 73%

Plasmid Mediated Salt Tolerance in Root Associated Bacteria from Erigerone linifolious

Yasmin¹,

Hasnain²

2000

Pakistan J. of Biological Sciences

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Abstract:Bacterial strains (which could tolerate 2-3 M NaCI in the growth medium) were isolated from the roots of Erigerane linifolious. They were EI-1, EI-2, El-3 (from histoplane of roots) and REI I -1, REI-2, REI-3, REI-4, REI-5 (from the rhizoplane). All bacterial strains were motile rods (except El-2 which were cocci), exhibiting either Gram-negative (El-1, El-2, El-3, REI-1) or Gram-variable (REI-2, REI-3, REI-4, REI-5) staining. These strains were affiliated with genus De/ya (EI-1), Vibrio (EI-3, REI-1), while four Gram-variable strains chaired characters with Bacillus pumilus. They have wide temperature and pH ranges with different optima. These strains also exhibit multiple salts/osmolytes/heavy metals/antibiotics resistance. Curing of plasmids from four of these strains revealed that salt tolerance and most of the other resistances were plasmid encoded. Plasmids residing in these halo-tolerant strains were conjugative (except pSH1413I. Hybridization experiments revealed that one of these plasmids (pSH1414) belonged to IncN group of plasmids.

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Section: Discussionsupporting

confidence: 73%

Plasmid Mediated Salt Tolerance in Root Associated Bacteria from Erigerone linifolious

Yasmin¹,

Hasnain²

2000

Pakistan J. of Biological Sciences

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“…ϩ antiporters have been implicated in pH regulation in other bacteria before (22,29). In addition, the intracellular formation of acids (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…To counteract the H ϩ expulsion and to maintain an intracellular pH of around 8.2, these bacteria possess Na ϩ /H ϩ antiporters (9,23). K ϩ /H ϩ antiporters have also been implicated in the regulation of the intracellular pH (29) in such organisms as the moderately halophilic and alkaliphilic methanogen Methanolobus taylorii GS-16 (22). In this respect, K ϩ ions play a role in pH homeostasis in Bacillus alcalophilus (14) and in the ureolytic bacterium Bacillus pasteurii (10).…”

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confidence: 99%

Sodium-coupled energy transduction in the newly isolated thermoalkaliphilic strain LBS3

et al. 1996

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Strain LBS3 is a novel anaerobic thermoalkaliphilic bacterium that grows optimally at pH 9.5 and 50؇C. Since a high concentration of Na ؉ ions is required for growth, we have analyzed the primary bioenergetic mechanism of energy transduction in this organism. For this purpose, a method was devised for the isolation of right-side-out membrane vesicles that are functional for the energy-dependent uptake of solutes. A strict requirement for Na ؉ was observed for the uptake of several amino acids, and in the case of L-leucine, it was concluded that amino acid uptake occurs in symport with Na ؉ ions. Further characterization of the leucine transport system revealed that its pH and temperature optima closely match the conditions that support the growth of strain LBS3. The ATPase activity associated with inside-out membrane vesicles was found to be stimulated by both Na ؉ and Li ؉ ions. These data suggest that the primary mechanism of energy transduction in the anaerobic thermoalkaliphilic strain LBS3 is dependent on sodium cycling. The implications of this finding for the mechanism of intracellular pH regulation are discussed.

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“…The energy in the ⌬ H ϩ is the sum of the energies in the transmembrane pH gradient (⌬pH) and the transmembrane electrical gradient (⌬). Most of the energy in the ⌬ H ϩ of Methanolobus taylorii is accounted for by its large ⌬ (i.e., the outside of the cell is more positively charged); its ⌬pH is therefore small or even negative (31). Methanolobus taylorii is a slight alkaliphile, and its small or negative ⌬pH allows it to grow with a near-neutral cytosol even when the external pH is above 7.…”

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confidence: 99%

Influence of pH on Ammonia Accumulation and Toxicity in Halophilic, Methylotrophic Methanogens

Kadam¹,

Boone²

1996

Appl Environ Microbiol

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112

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We studied the effects of pH and ammonia concentration on the growth of three methanogens. These three halophilic, methylotrophic methanogens, Methanolobus bombayensis, Methanolobus taylorii, and Methanohalophilus zhilinaeae, grew at environmental pH ranges that overlapped with each other and spanned the pH range from 7.0 to 9.5. During growth they had reversed membrane pH gradients (⌬pH) at all pH values tested. The ⌬pH was in the range of ؊0.4 to ؊0.9 pH units, with the cytosol being more acidic than the environmental pH. Methanohalophilus zhilinaeae had the most negative ⌬pH (؊0.9 pH units). These negative pH gradients resulted in the accumulation of ammonium (NH 4 ؉), and when grown at the highest external ammonia concentrations that allowed good growth, cells had cytosolic NH 4 ؉ concentrations as high as 180 mM. The high concentrations of cytosolic NH 4 ؉ were accompanied by greater ⌬pH and lower concentrations of the major cytosolic cation K ؉ (compared with cells grown in medium with only 5 mM ammonia). Methanolobus bombayensis and Methanolobus taylorii were more sensitive to total external ammonia at higher external pH values, but the inhibitory concentration of un-ionized ammonia that resulted in a 50% reduction of the growth rate was about 2 to 5 mM, regardless of the pH. This is consistent with growth inhibition by ammonia in other bacteria. However, Methanohalophilus zhilinaeae was more resistant to un-ionized ammonia than any other known organism. It had a 50% inhibitory concentration for un-ionized ammonia of 13 mM at pH 8.5 and 45 mM at pH 9.5. We examined the effects of pH on three ammonia-assimilating activities (glutamine synthetase, glutamate dehydrogenase, and alanine dehydrogenase) in cell lysates and found that the pH ranges were consistent with the observed ranges of intracellular pH.

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Potassium extrusion by the moderately halophilic and alkaliphilic methanogen methanolobus taylorii GS-16 and homeostasis of cytosolic pH

Cited by 9 publications

References 46 publications

Plasmid Mediated Salt Tolerance in Root Associated Bacteria from Erigerone linifolious

Plasmid Mediated Salt Tolerance in Root Associated Bacteria from Erigerone linifolious

Sodium-coupled energy transduction in the newly isolated thermoalkaliphilic strain LBS3

Influence of pH on Ammonia Accumulation and Toxicity in Halophilic, Methylotrophic Methanogens

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