ISSN:
1573-5036
Keywords:
Batch culture
;
Frankia
;
HFPAr13
;
Nitrogenase
;
Vesicles
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Kinetics of growth and nitrogenase induction inFrankia sp. Ar13 were studied in batch culture. Growth on defined medium with NH 4 + as the N source displayed typical batch culture kinetics; however, a short stationary phase was followed by autolysis. Removal of NH 4 + arrested growth and initiated vesicle differentiation. Vesicle numbers increased linearly and were paralleled by a rise in nitrogenase (acetylene reduction) activity. Nitrogenase activity (10 nM C2H4·mg protein−1·min−1) was sufficient to support growth on N2 and protein levels rose in parallel with nitrogenase induction. Optimal conditions for vesicle and nitrogenase induction were investigated. Maximum rates of acetylene reduction were obtained with 5 to 10 mM K2 HPO4/KH2PO4, 0.1 mM CaCl2 and MgSO4. The optimum pH for acetylene reduction and respiration was around 6.7. The amount (5 to 10 μg protein/ml) and stage (exponential) of growth of the ammonium-grown inoculum strongly influenced the subsequent development of nitrogenase activity. Propionate was the most effective carbon source tested for nitrogenase induction. Respiration in propionate-grown cells was stimulated by CO2 and biotin, suggesting that propionate is metabolized via the propionyl CoA pathway.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02277840
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