| Gas vesicle is considered a major factor providing buoyancy for cyanobacteria ascending. However, whether other buoyancy contributing factors exist is still unclear. In this study, we combined indoor bloom simulation and field experiments to explore the impact of intercellular spaces on algal bloom formation. Indoor bloom simulation studies indicated that cyanobacteria exist as single cells when floating, but form small colonies at port 6. Cell ballast analysis ［exopolysaccharide (EPS), cellular dry weight, protein, etc.］ showed that EPS exhibits the most rapid change rate and the maximum level of cyanobacteria rises at port 6, which were 3.02, 10.38 and 15.73 pg/cell in three tests respectively. Field algae investigation revealed abundant intercellular spaces within algal colonies. When the field colonies were treated with 1.0 MPa pressure and ultrasonic processor at 40 Hz for 1 min, respectively, intercellular spaces disappeared and gas vesicles collapsed under 1.0 MPa pressure, causing increasing cyanobacteria failure. Under sonication, algal colonies were broken down into single cells that became suspended in water, but gas vesicles remained intact. These results suggested that single algal cells aggregate into colonies through EPS and form intercellular spaces to provide buoyancy, which is one of the major factors for bloom formation. |
