Aerobic Microbial Growth at Low Oxygen Concentrations

AUTOR(ES)

Johnson, Marvin J.

RESUMO

Sterilizable membrane probes were used to study the relation between oxygen concentration and respiration rate in Candida utilis growing on acetate. When the organism was grown in a continuous fermentor at various dissolved oxygen concentrations (0.23 × 10−6 to 32 × 10−6m), with time allowed for full adaptation to each oxygen concentration, the relationship between oxygen concentration and growth rate simulated Michaelis-Menten behavior, giving an apparent Km for oxygen of 1.3 × 10−6m. When respiration rate was measured at various oxygen concentrations without allowing time for adaptation, it was found that the respiration rate was directly proportional to O2 concentration at low O2 concentrations, and independent of O2 concentration at high O2 concentrations. Transition from one type of behavior to the other was fairly abrupt. The respiration rate in the presence of excess oxygen depended on the O2 concentration at which the cells were grown, but the rate at low O2 concentrations did not. There was evidence that, at low oxygen concentrations, oxygen diffusion through the cell substance limits respiration rate, at least in part.

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