Modeling growth and biochemical activities of Azospirillum spp.
An unstructured mathematical model was developed and used in the evaluation of biochemical activities of four Azospirillum spp. strains grown in batch cultures in a high C/N-ratio medium. The strains were evaluated for their ability to grow on fructose and produce exo-polysaccharide, and to sustain nitrogenase activity by using fructose or polysaccharides. Quantitative expression of the regulation of polysaccharide synthesis and nitrogenase (acetylene reduction) activity from the mineral nitrogen and sugar concentration in the culture medium was achieved. It was found that, during growth, Azospirillum spp. produced significant quantities of exocellular and capsular polysaccharide, whereas after depletion of the carbon source from the culture medium polysaccharides were consumed, especially in A. lipoferum strains. Significant nitrogenase activity was detected during polysaccharide degradation. Oxygen uptake was high during assimilation of fructose and low during polysaccharide degradation.
Kefalogianni
I
I
Department of Agricultural Biotechnology, Agricultural University of Athens, Greece.
Aggelis
G
G
D000114:Acetylene / Q000378:metabolism; D016949:Azospirillum / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D015806:Azospirillum brasilense / Q000254:growth & development / Q000378:metabolism; D001673:Biodegradation, Environmental; D003470:Culture Media; D008962:Models, Theoretical; D009591:Nitrogenase / Q000378:metabolism; D010101:Oxygen Consumption; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis
D003470:Culture Media; D011135:Polysaccharides, Bacterial; D009591:Nitrogenase; D000114:Acetylene