ISSN:
0006-3592
Keywords:
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
The physiological activity of microorganisms in environments with low dissolved oxygen concentrations often differs from the metabolic activity of the same cells growing under fully aerobic or anaerobic conditions. This article describes a laboratory-scale system for the control of dissolved oxygen at low levels while maintaining other parameters, such as agitator speed, gas flowrate, position of sparger outlet, and temperature at fixed values. Thus, it is possible to attribute in dilute nonviscous fermentations all physiologic changes solely to changes in dissolved oxygen. Experiments were conducted with Azotobacter vinelandii and Escherichia coli. Critical oxygen concentrations for growth (that value of oxygen allowing growth at 97% of μmax) were measured as 0.35 ± 0.03 mg/L for A. vinelandii and 0.12 ± 0.03 mg/L for E. coli. These values are significantly different from the commonly quoted values for critical oxygen concentrations based on respiration rates. Because of the superior dissolved oxygen control system and an improved experimental protocol preventing CO2 limitation, we believe that the values reported in this work more closely represent reality.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260270208
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