Regulation of respiratory activity by oxygen in Arthrobacter fluorescens ammonium-limited chemostat culture

1985 ◽  
Vol 31 (10) ◽  
pp. 896-899 ◽  
Author(s):  
I. Cacciari ◽  
D. Lippi ◽  
S. Ippoliti ◽  
T. Pietrosanti ◽  
W. Pietrosanti
Keyword(s):  
Growth Rate ◽  
Dissolved Oxygen ◽  
Respiratory Rate ◽  
Oxygen Concentration ◽  
Respiration Rate ◽  
Inverse Relationship ◽  
Respiratory Activity ◽  
Chemostat Culture ◽  
Oxygen Limitation ◽  
Dissolved Oxygen Concentration

The effect of a sudden imposition of either oxygen limitation or over oxygenation on an Arthrobacter sp. ammonium-limited chemostat culture was studied at growth rate of 0.03 h−1. Growth and respiratory activity of the cultures were examined during the transition periods and at both steady-states. Arthrobacter fluorescens responded to oxygen limitation by increasing respiratory rate and degrading polysaccharide content. In contrast, an increase in dissolved oxygen concentration caused a decrease in respiration rate and an increase in biosynthesis of endogenous polysaccharides. Under both conditions an inverse relationship seemed to occur between respiration rate and yield coefficients.

Estimation of Whole Pond Respiration Rate

1990 ◽  
Vol 47 (4) ◽  
pp. 682-686 ◽  
Author(s):  
Charles P. Madenjian ◽  
Gary L. Rogers ◽  
Arlo W. Fast
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Respiration Rate ◽  
Tangent Line ◽  
New Method ◽  
Dissolved Oxygen Concentration ◽  
Rate Estimation ◽  
Quadratic Curve ◽  
Tangent Method

A regression application of the whole pond respiration–diffusion (WPRD) model to overnight observations of dissolved oxygen concentration (DO) was introduced as a new method to estimate whole pond respiration rate. A new modification of the Welch procedure was also presented. These two techniques were compared with the tangent method for whole pond respiration rate estimation. The tangent method required fitting a quadratic curve to observed DO; and then calculating the slope of the tangent line to the curve at the time the curve reached 100% saturation of DO. When the quadratic was fitted to DO observed during both day and light, the tangent method often yielded inaccurate estimates of whole pond respiration rate. Estimates by the tangent method were sensitive to the time at which 100% saturation of DO occurred. The WPRD model regression and the modified Welch procedure were recommended to estimate whole pond respiration rate.

Effect of Physicochemical Variables on Algal Autoflotation

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1769-1778 ◽  
Author(s):  
S.-I. Lee ◽  
B. Koopman ◽  
E. P. Lincoln
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Retention Time ◽  
Contact Time ◽  
Pilot Scale ◽  
Dissolved Oxygen Concentration ◽  
Physicochemical Variables ◽  
Rise Rate ◽  
Mixing Intensity ◽  
Maximum Rise

Combined chemical flocculation and autoflotation were examined using pilot scale process with chitosan and alum as flocculants. Positive correlation was observed between dissolved oxygen concentration and rise rate. Rise rate depended entirely on the autoflotation parameters: mixing intensity, retention time, and flocculant contact time. Also, rise rate was influenced by the type of flocculant used. The maximum rise rate with alum was observed to be 70 m/h, whereas that with chitosan was approximately 420 m/h. The efficiency of the flocculation-autoflotation process was superior to that of the flocculation-sedimentation process.

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