Outdoor algal mass cultures—II. Photosynthetic yield limitations☆

A. Physiology and metabolic studies . . . . . . . . . . . . . . . . . . . . . . . . . . 393 B. Enzymes, nuclear components , genetic and in fo rmat ion mechanisms . . . . . . . . . . . 399 C. Alcohols, solvents and gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 D. Organic acids, antibiotics, v i tamins , polysacehaxides and other products . . . . . . . . 401 E. Mixed populat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402 F. Cells and tissues of higher organisms . . . . . . . . . . . . . . . . . . . . . . . . 404

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Continuous cultivation of microorganisms

A critical review of batch-culture freshwater algal toxicity test methods (algal growth inhibition tests) is presented. Interlaboratory comparisons have revealed that the results from such tests can vary a great deal, in some cases by more than three orders of magnitude. The potential causes of variability are the physical/chemical experimental parameters. Algal tests, however, need not be very strictly standardized in order to be reproducible if tests are appropriately conducted and the experimental parameters are understood and controlled. Many algal toxicity data reported in the literature seem to have been generated from tests performed with an excessively high biomass and under poor gas-exchange conditions, the combination of which will cause an insufficient supply of carbon dioxide leading to high pH levels and sometimes even to mass-transport (carbon dioxide)-limited linear growth. Poor gas-exchange conditions will prevail unless the test flasks are shaken or aerated continuously. Literature data on the toxicity of chemicals to algae should therefore be used only with careful evaluation of the test method involved.

https://setac.onlinelibrary.wiley.com/doi/pdf/10.1002/etc.5620080807

Methods for growth inhibition toxicity tests with freshwater algae

Summary: Growth efficiency (c) and specific maintenance rate constant (μe) were determined in continuous cultures of the cyanobacterium Oscillatoria agardhii Gomont, in light energy-limiting conditions, according to the formula μ = cq
E – μe in which q
E is the specific light energy uptake rate. Values of the efficiency factor c varied with irradiance from 0.23 at 0.5 W m−2 to 0.05 at 40 W m−2. The specific maintenance rate constant was 0.001 h−1. The culture pH value influenced c and μe
. A diurnal light/dark cycle with a 16 h photoperiod did not affect either of the two parameters, μe and c. The relationship between growth rate and light energy uptake rate, embodied in the above formula, was also valid for nitrogen (nitrate)-limited cultures.

Growth Kinetics of Oscillatoria agardhii Gomont in Continuous Culture, Limited in its Growth by the Light Energy Supply

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1461&context=water_rep

The effect of carbon on algal growth—Its relationship to eutrophication

An analytical model of a continuously fed, completely mixed Chlorella culture in which light is the factor limiting growth is presented. The conclusions from the theory are that in a culture of this type the population density is directly proportional to the retention time and the production rate is independent of retention time. Experimental data are presented to verify the theoretical conclusions.

Sotiris P. Koutsoyannis

Papers

Light-Limited Growth of Chlorella in Continuous Cultures