ISSN:
1432-072X
Keywords:
Eubacterium acidaminophilum
;
Diauxic growth
;
Growth yields
;
Formate metabolism
;
Glycine reductase
;
Sarcosine reductase
;
Betaine reductase
;
Creatine metabolism
;
Selenium incorporation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The obligate anaerobe Eubacterium acidaminophilum metabolized the glycine derivatives sarcosine (N-monomethyl glycine) and betaine (N-trimethyl glycine) only by reduction in a reaction analogous to glycine reductase. Using formate as electron donor, sarcosine and betaine were stoichiometrically reduced to acetate and methylamine or trimethylamine, respectively. The N-methyl groups of the cosubstrates or of the amines produced were not transformed to CO2 or acetate. Under optimum conditions (formate/acceptor ratio of 1 to 1.2, 34°C, pH 7.3) the doubling times were 4.2 h on formate/sarcosine and 3.6 h on formate/betaine. The molar growth yields were 8.15 and 8.5 g dry cell mass per mol sarcosine and betaine, respectively. The assays for sarcosine reductase and betaine reductase were optimized in cell extracts; NADPH was preferred as physiological electron donor compared to NADH, dithioerythritol was used as artificial donor; no requirements for AMP and ADP could be detected. Growth experiments mostly revealed diauxic substrate utilization pattern using different combinations of glycine, sarcosine, and betaine (plus formate) and inocula from different precultures. Glycine was always utilized first, what coincided with the presence of glycine reductase activity under all growth conditions except for serine as substrate. Sarcosine reductase and betaine reductase were only induced when E. acidaminophilum was grown on sarcosine and betaine, respectively. Creatine was metabolized via sarcosine. [75Se]-selenite labeling revealed about the same pattern of predominant labeled proteins in glycine-, sarcosine-, and betaine-grown cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00277541
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