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Photosynthetic characteristics of Spirulina platensis on solid support. Chlorophyll fluorescence kinetics
Author(s) -
SIVAK MIRTA N.,
VONSHAK AVIGAD
Publication year - 1988
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1988.tb00258.x
Subject(s) - photosynthesis , photoinhibition , chlorophyll fluorescence , fluorescence , chlorophyll a , chlorophyll , oxygen evolution , kinetics , quenching (fluorescence) , chemistry , photochemistry , analytical chemistry (journal) , botany , biology , photosystem ii , environmental chemistry , optics , physics , electrode , quantum mechanics , electrochemistry
SUMMARY Several aspects of photosynthesis in vivo (CO 2 and O 2 exchange, chlorophyll fluorescence and its quenching components) were measured in Spirulina platensis after filtering suspensions of this cyanobacteria through fibre glass filters. This simple procedure allowed the use of methods which previously could be applied only to leaves. Fluorescence characteristics displayed by Spirulina in suspension or collected on the solid support were similar, indicating that filtration and assay did not by themselves affect the photosynthetic process. When oxygen evolution and carbon dioxide uptake were followed simultaneously their kinetics differed, and the rate of O 2 evolution was often higher than the rate of CO 2 uptake. Slow kinetics and other fluorescence characteristics were strongly modified in aged cultures or when nutrient supply during growth was not optimal, or after exposure to photoinhibitory photon flux densities. Photoinhibition and recovery were studied in two strains differing in their sensitivity to high photon flux densities. During illumination using high photon flux densities two phases could be determined. After a few minutes variable fluorescence decreased and ‘dark fluorescence’ (F o ) was unchanged, but after prolonged illumination F o increased. The latter phase appeared earlier in the more sensitive strain and could be brought forward by increasing photon flux densities or, in some circumstances, by increasing [O 2 ]. Results are discussed in terms of the underlying relationships between electron transport and photosynthetic carbon assimilation and of the use of chlorophyll fluorescence as a diagnostic probe. It is suggested that measurement of chlorophyll fluorescence (by itself or in conjunction with quantum yield) on cyanobacteria or algae collected on solid support could provide a convenient screening procedure to assess sensitivity to photoinhibition and to other kinds of stress likely to be encountered in large‐scale culture.