Role of Cell Hydrophobicity on Colony Formation in Microcystis (Cyanobacteria)

Abstract

Colony formation is highly import ant for the competitive advantage of the cyanobacterium Microcystis over other phytoplankton species. The laboratory-grown colonial Microcystis strains isolated from Lake Taihu (China) maintained colonial forms under the low light condition (10 μE m ) 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 cell-cell adherence and colony formation. Phosphate-limitation, nitrate-limitation 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. IntroductionAs a result of anthropogenic eutrophication, environmental problems caused by cyanobacterial blooms in lakes, ponds, rivers and reservoirs have been increasingly documented across the world (LEHMAN, 2005;KEMP and JOHN, 2006). Microcystis spp. are common bloomforming cyanobacteria. It is already known that, under natural conditions, Microcystis occurs as colonial aggregates constrained by an amorphous mucilage or sheath (OTSUKA et al., 2000). However, during long-term storage and cultivation under laboratory conditions, the characteristics of colonies disappear, and Microcystis exists mainly as single cells and a few paired cells (ZHANG et al., 2007). Colony formation is highly important for the competitive advantage of Microcystis over other phytoplankton species. It is suggested that formation of Microcystis colonies is helpful to vertical migration and defense against predation pressure 142 H. YANG et al.

Iron and phosphorus deprivation induce sociality in the marine bloom-forming cyanobacterium Trichodesmium

“…Moreover, high concentrations of combined N and P caused colonial morphologies of Microcystis to disappear [65]. Other environmental drivers (e.g., temperature, salinity, pH, light, and UVR) [65][66][67] and biotic factors (e.g., grazing, allelopathy, and other interspecific interactions) [68][69][70][71] induce colony formation in cyanobacteria and other phytoplankton. Dominant factors such as nutrient deprivation may drive the formation of colonies.…”

Functional assessment of mycosporine‐like amino acids in Microcystis aeruginosa strain PCC 7806

“…Beyond quantitative differences, the mutant exhibited alterations of the EPS hydrophobicity, indicating changes in the chemical composition of the matrix. EPS of Microcystis is involved in colony formation and reacts dynamically in response to environmental stimuli (Beardall et al, 2009;Yamamoto et al, 2011;Yang et al, 2011). Because colony formation is a trait commonly lost in laboratory-cultured Microcystis, we could not suffi-ciently evaluate the impact of MAAs on colony formation and cell-cell recognition in Microcystis.…”

Characteristics and roles of Microcystis extracellular polymeric substances (EPS) in cyanobacterial blooms: a short review

“…Uronic acids might mainly contribute to the anionic character of cyanobacterial EPS (Verspagen et al 2006;Klock et al 2007). The hydrophobic interaction could play a key role in the EPS assembly from phytoplankton (Ding et al 2009), and the hydrophobicity of colony was stronger than that of single cell (Yang et al 2011;Liu et al 2016). Yang et al (2011) further specified that the extracellular polysaccharides may play a role in adhering cells together to form colonies.…”

“…The hydrophobic interaction could play a key role in the EPS assembly from phytoplankton (Ding et al 2009), and the hydrophobicity of colony was stronger than that of single cell (Yang et al 2011;Liu et al 2016). Yang et al (2011) further specified that the extracellular polysaccharides may play a role in adhering cells together to form colonies. Zhang et al (2007) observed that the colonial Microcystis aeruginosa cells have thicker polysaccharides envelope than the unicellular cells.…”