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

Journal Article · · Applied and Environmental Microbiology; (United States)
OSTI ID:6963739
;  [1]; ;  [2]
  1. Boston College, Chestnut Hill, MA (United States)
  2. Univ. of California, Los Angeles (United States)

Methanohalophilus strain FDF1, a member of the halophilic genus of methanogens, can grow over a range of external NaCl concentrations from 1.2 to 2.9 M and utilize methanol, trimethylamine, and dimethyl sulfide as substrates for methanogenesis. It produces the osmolytes glycine betaine, [beta]-glutamine, and N[sup [epsilon]]-acetyl-[beta]-lysine with increasing external NaCl, but the relative ratio of these zwitterions depends primarily on the methanogenic substrate and less on the external osmolarity. When the cells are grown on methanol in defined medium, accumulation of glucine betaine predominates over the other zwitterionic solutes. The cells also synthesized a carbohydrate which was not detected in cells grown on trimethylamine. This negatively charged compound, identified as [alpha]-glucosylglycerate from the [sup 13]C and [sup 1]H chemical shifts, does not act as an osmoregulatory solute in the salt range 1.4 to 2.7 M in this methanogen as evidenced by its invariant intracellular concentration. [sup 13]CH[sub 3]OH-pulse/[sup 12]CH[sub 3]OH-chase experiments were used to determine the half-life for these organic solute pools in the cells. L-[alpha]-Glutamate showed a rapid loss of heavy isotope, indicating that L-[alpha]-glutamate functions as a biosynthetic intermediate in these cells. Measurable turnover rates for both [beta]-glutamine, which acts as an osmolyte, and [alpha]-glucosylglycerate suggest that they function as metabolic intermediates as well. Molecules which function solely as osmolytes showed a slower turnover consistent with their roles as osmotic solutes in Methanohalophilus strain FDF1.

OSTI ID:
6963739
Journal Information:
Applied and Environmental Microbiology; (United States), Journal Name: Applied and Environmental Microbiology; (United States) Vol. 58:8; ISSN AEMIDF; ISSN 0099-2240
Country of Publication:
United States
Language:
English