Studies On The Genetic Diversity And Morphological And Physiological Adaptation Of Microcystis

Bloom-forming cyanobacterial Microcystis has been widely reported worldwide in many freshwater bodies, mainly owing to its harmful effect, directly or indirectly, to animals and human beings. Most of Microcystis can produce microcystins, a cyclic heptapetide toxins thought to be a tumor promoter for primary liver cancer in human beings. Therefore, great attention has been focused on the formation mechanism and harmful effects of Microcystis blooms by researchers in areas such as aquatic ecology, phycology, environmental sciences and so on. As already illustrated, bloom-forming cyanobacteria, in particularly Microcystis, has developed a sound ecological strategies to form water bloom with a series of special physiological mechanisms and adaptation characters during evolution. While most of bloom of Microcysts exists as the colonial form, the role of colonial form in the formation and persistence of bloom has been investigated over the decades. Due to the lack of comparison, however, the mechanism on the role of colonial form in the competition remains largely unknown. Previous studied in our laboratory showed the differences in physiological adaptation between colonial form and single-celled form of Microcystis. To further investigate the mechanism of the role of colonial form as well as the diversity of Microcystis, this dissertation focuses on the following aspects: 1. what are advantageous physiological mechanisms of colonial Microcystis in bloom-forming? 2. how does single-celled Microcystis differentiate to colonial one during the formation of Microcystis bloom, and what are the mechanisms? 3. how are the evolution relationship, diversity and toxin profiles of Microcystis strains in water bodies of China? The main results are...