Variation in the growth ofMicrocystis aeruginosadepending on colony size and position in colonies

Abstract

-Growth of colonial Microcystis aeruginosa was investigated by performing an incubation experiment. Colonies of M. aeruginosa were separated based on size (colony diameter <100 mm, 100-200 mm and > 200 mm) by filtration. Additionally, the cells around the surface of the colonies were separated from those inside the colonies by short-term ultrasonic treatment followed by filtration. Experimental results indicate that M. aeruginosa grew continuously throughout a 35-day incubation period in a nutrient-rich medium at specific growth rates between 0.045 and 0.310 d x1 . On day 14, larger colonies exhibited insignificantly higher specific growth rates. However, on day 35, the specific growth rates of colonies with diameters less than 100 mm insignificantly exceeded those of larger colonies. Internal cells of the colonies tended to grow faster than peripheral cells. Furthermore, the specific growth rates of the cells that comprised colonies with diameters of below 200 mm exceeded those of peripheral cells. These results suggest a potential growth strategy of M. aeruginosa in maintaining a high growth rate, eventually leading to the dominance of large colonies, which have notable ecological advantages over smaller ones.

Importance of large colony formation in bloom-forming cyanobacteria to dominate in eutrophic ponds

“…As also observed in this study, the relative abundances of cyanobacteria in waters with very high nutrient concentrations were generally small; in such cases, diatoms and/or green algae commonly dominated. Yamamoto and Shiah (2010) suggested that the active growth of M. aeruginosa occurs mainly inside colonies, and when the growth of these cells begins to be suppressed as a result of self-shading, peripheral cells separate as smaller colonies. Since the growth rate of small colonies exceeds that of peripheral cells, this growth mechanism enables a population of M. aeruginosa to maintain high growth activity (Yamamoto and Shiah, 2010).…”

“…Yamamoto and Shiah (2010) suggested that the active growth of M. aeruginosa occurs mainly inside colonies, and when the growth of these cells begins to be suppressed as a result of self-shading, peripheral cells separate as smaller colonies. Since the growth rate of small colonies exceeds that of peripheral cells, this growth mechanism enables a population of M. aeruginosa to maintain high growth activity (Yamamoto and Shiah, 2010). The present study revealed that large colonies of M. aeruginosa formed only when this species exclusively dominated the community of photosynthetic plankters; the colonies were not significantly large even when the cyanobacterium accounted for 54.1 or 85.2% of the total biovolume of the photosynthetic plankters.…”

“…Recently, Yamamoto and Shiah (2010) suggested that the growth mechanism of Microcystis aeruginosa serves to increase the number of large colonies as the bloom proceeds. Considering the ecological advantages of large colonies, as described above, the growth mechanism of M. aeruginosa seems reasonable to facilitate its dominance in the plankton community.…”

Phenotype and temperature affect the affinity for dissolved inorganic carbon in a cyanobacterium Microcystis

“…Among these factors, the uptake and utilization of dissolved inorganic carbon (DIC) are thought to be critical factors (Yamamoto & Shiah, 2010).…”

Recruitment of cyanobacteria from the sediments in the eutrophic Shanzi Reservoir

“…The remarkable effects of physical disturbance on Microcystis and Oscillatoria in this work explained the better recruitment of cyanobacteria under disturbance, fitting well with physiological research on Microcystis recruitment. [47,48] The aerobic environment created by physical disturbance benefited their resuscitation from the sediment into water body. [49] It was reported that the single vertical convection type of water temperature in Shanzi reservoir could form a stable thermal stratification from March to November.…”