Composition, variation, and dynamics of major osmotic solutes in Methanohalophilus strain FDF1

Article Abstract:

The types and amounts of organic solutes in Methanohalophilus FDF1 was found to depend on the substrate used for methanogenesis. Between methanol and trimethylamine, the latter's metabolism resulted in the generation of ammonium which was used to produce solutes with high nitrogen content. Osmolytes identified were glycine betaine and N-acetyl-beta-lysine. Although beta-glutamine can function as an osmolyte, it can also be metabolized. Cells grown in methanol produced glucosylglycerate as a biosynthetic intermediate. L-alpha-glutamine was rapidly metabolized by both groups of cells.

author: Roberts, Mary F., Robertson, Diane E., Lai, Mei-Chin, Gunsalus, Robert P.
Physiological aspects, Methanobacteriaceae, Methanogens

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Regulatory factors associated with synthesis of the osmolyte glycine betaine in the halophilic methanoarchaeon Methanohalophilus portucalensis

Article Abstract:

Research was conducted to examine the regulatory factors associated with synthesis of the osmolyte glycine betaine in the halophilic methanoarchaeon Methanohalophilus portucalensis. Previous nuclear magnetic resonance 13C-labelling studies showing that the de novo synthesis of betaine proceeds from sarcosine, dimethylglycine and glycine to form betaine through threefold methylation was confirmed by in vivo and in vitro betaine formation assays. Results indicate that the intracellular levels of potassium and sarcosine are associated with betain synthesis regulation.

author: Lai, Mei-Chin, Yang, Daw-Renn, Chuang, Ming-Jen
Glutamine

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Halotolerance in Methanosarcina spp.: role of N(super epsilon)-acetyl-beta-lysine, alpha-glutamate, glycine betaine, and K+ as compatible solutes for osmotic adaptation

Article Abstract:

The regulation of K+ ion, N(super epsilon)-acetyl-beta-lysine, glycine betaine, and alpha-glutamate levels in response to osmotic effects is responsible for the mechanism of halotolerance in Methanosarcina spp. An increase in osmolality from 0.3 to 1.0 osmol/kg increases the K+ ion concentration and the synthesis of alpha-glutamate in M. thermophila. At osmolalities above 1.0 osmol/kg, the alpha-glutamate levels remain steady and the level of beta-amino acid N(super epsilon)-acetyl-beta-lysine increases.

author: Sowers, Kevin R., Gunsalus, Robert P.
Observations, Osmotic pressure

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subjects list: Research, Fluid-electrolyte balance, Osmoregulation
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