%0 Journal Article %A Lees, H. %A Postgate, J. R. %T The Behaviour of Azotobacter chroococcum in Oxygen- and Phosphate-limited Chemostat Culture %D 1973 %J Microbiology, %V 75 %N 1 %P 161-166 %@ 1465-2080 %R https://doi.org/10.1099/00221287-75-1-161 %I Microbiology Society, %X SUMMARY: Oxygen-limited chemostat cultures of nitrogen-fixing Azotobacter chroococcum showed an inverse relation between biomass and dilution rate, accounted for largely by increased polysaccharide and polyhydroxybutyrate content. Abrupt increase in pO2 led to immediate increase in CO2 output followed later by increase in biomass and transition to N2 limitation; viability on N-free and NH4-containing media remained at 80 to 100% during O2 stress. P-limited populations showed no respiratory reponse to O2 stress, viability dropped rapidly on N-free medium though the populations were 100% viable on NH4 medium. These findings support the view that respiration in these bacteria has, in part, a protective function for nitrogenase. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-75-1-161