ISSN:
1432-072X
Keywords:
Alkaline phosphatase
;
Continuous culture
;
Growth yields
;
Phosphate
;
Phosphorus nutrition
;
Polyphosphate
;
Rhizobium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract With continuous cultures in a fully defined minimal salts medium steady states were achieved at both limiting and non-limiting concentrations of phosphate in the inflowing medium for Rhizobium trifolii WU95, cowpea Rhizobium NGR234, and Bradyrhizobium CB756. Millimolar growth yields obtained from P-limited cultures varied over 2-fold from 3.2 g dry weight·(mmol P)-1 for WU95 to 5.3 g dry weight·(mmol P)-1 for CB756 and 7.2 g dry weight·(mmol P)-1 for NGR234. For both WU95 and NGR234 growth under P-excess conditions resulted in elevated levels of total biomass P and the storage compound polyphosphate, compared with P-limited cultures. However, P-limited cultures of these two strains still contained significant quantities of polyphosphate. The P-status for CB756 cultures did not affect either total biomass P or polyphosphate levels. Alkaline phosphatase was maximally derepressed in P-limited cultures of WU95 and NGR234. However, in CB756 alkaline phosphatase was not detected at significant levels regardless of its P supply. These data suggest that growth of rhizobia is controlled predominantly by the attainment of a critical internal P level.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00454942
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