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Comparison of the light‐limited growth of the nitrogen‐fixing cyanobacteria Anabaena and Aphanizomenon
Author(s) -
DE NOBEL W. T. PIM,
MATTHIJS HANS C. P.,
VON ELERT ERIC,
MUR LUUC R.
Publication year - 1998
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 - 10.1046/j.1469-8137.1998.00155.x
Subject(s) - aphanizomenon , anabaena , biology , botany , cyanobacteria , phycoerythrin , photosynthesis , nitrogen fixation , flow cytometry , genetics , bacteria
The effect of simultaneous N 2 fixation and light limitation on the growth of two strains of Anabaena sp. Bory de St. Vincent and Aphanizomenon flos‐aquae (L.) Ralfs was investigated using continuous cultures. Under severely light‐limited conditions, Aphanizomenon showed a broader absorption spectrum (due to the presence of phycoerythrin), a higher maximum efficiency of photosynthesis, a higher steady‐state N 2 fixation activity and a higher growth affinity for light than did Anabaena . On the other hand, under light saturation, Anabaena showed a higher maximum rate of O 2 production and a higher maximum specific growth rate than Aphanizomenon . These monoculture results characterize Anabaena and Aphanizomenon , in relative terms, as a ‘sun’ and a ‘shade’ species respectively, and are in accordance with field observations. The difference between the two species in their acclimatory response is discussed in terms of a species‐specific alteration of the PSI∶PSII stoichiometry. Besides the species‐specific modulation of the accessory pigments, such an acclimation would provide a biochemical basis for the observed physiological differences. The monoculture results were used to differentiate the niches of the two species and suggested that Aphanizomenon would competitively displace Anabaena under N 2 ‐fixing, light‐limited conditions. However, when both species were grown together, Anabaena became dominant and seemed to be the superior competitor for light. In order to explain this finding, the possible effects of release of allelopathic compounds, or dynamic aspects of light supply, are discussed.