Abstract
Colony formation is highly import ant for the competitive advantage of the cyanobacterium Microcystis over other phytoplankton species. The laboratoryโgrown colonial Microcystis strains isolated from Lake Taihu (China) maintained colonial forms under the low light condition (10 ฮผE m^โ2^ s^โ1^). The cell surface hydrophobicities of the Microcystis colonies were measured by cyanobacterial adherence to xylene in comparison with unicellular Microcystis strains. The cells of the tested colonial strains were all hydrophobic, while the cells of the tested unicellular strains were all hydrophilic. Incubation under the higher light condition (75 ฮผE m^โ2^ s^โ1^) leaded to the significant decrease in the cell hydrophobicities of the colonial Microcystis and the transition from colonial forms to unicellular forms. These findings indicated that the cell hydrophobicity of Microcystis may play a role in cellโcell adherence and colony formation. Phosphateโlimitation, nitrateโlimitation and pH did not affect cell hydrophobicities of colonial Microcystis. Treatment with proteolytic enzymes had no effect on the cell hydrophobicity, indicating that cell surface proteins did not contribute to high cell hydrophobicity. (ยฉ 2011 WILEYโVCH Verlag GmbH & Co. KGaA, Weinheim)