Abstract
Z-X. Wu and L-R. Song. 2007. Physiological comparison between colonial and unicellular forms of Microcystis aeruginosa Kütz. (Cyanobacteria). Phycologia 47: 98–104. DOI: 10.2216/07–36.1
In order to gain insight into the bloom sustainment of colonial Microcystis aeruginosa Kütz., physiological characterizations were undertaken in this study. Compared with unicellular Microcystis, colonial Microcystis phenotypes exhibited a higher maximum photosynthetic rate (Pm), a higher maximum electron transfer rate (ETRmax), higher phycocyanin content, and a higher affinity for inorganic carbon (K0.5 DIC ≤ 8.4 ± 0.7 µM) during the growth period monitored in this study. This suggests that photosynthetic efficiency is a dominant physiological adaptation found in colonial Microcystis, thus promoting bloom sustainment. In addition, the high content of soluble and total carbohydrates in colonial Microcystis suggests that this phenotype may possess a higher ability to tolerate enhanced stress conditions when compared to unicellular (noncolonial) phenotypes. Therefore, high photosynthetic activities and high tolerance abilities may explain the bloom sustainment of colonial Microcystis in eutrophic lakes.
ACKNOWLEDGMENTS
We thank the financial support by National Key Project for Basic Research (2002CB412306), Project of Chinese Academy of Sciences (KZCX2-YW-426) and National Hi-Tech Research and Development Program of China (2005AA60101005). We also thank anonymous referees for critical comments and suggestions.