Colony is a key to Microcystis becoming a dominant population and forming blooms. To find the mechanism of colony formation, we investigated cell wall structures of colonial and unicellular strains. Results showed that colonial strains had significant surface layer protein (S-layer) on the surface of cells than unicellular strains by transmission electron microscopy. Western blot showed colonial strains had more S-layer than the unicellular strains. When the S-layer gene (GenBank accession number CAO89090.1) of Microcystis aeruginosa PCC7806 was expressed in Synechocystis sp. PCC6803, PCC6803 aggregated into colonial morphology. The results indicated that the S-layer could promote colony formation in Microcystis. Based on the S-layer sequences of PCC6803 and PCC7806, nine S-layer genes in other Microcystis strains were screened from the GenBank. Sequence comparing showed that the S-layers conserved regions were all located in N-terminal. The S-layers contain repeats-in-toxin (RTX) sequences with Ca²⁺-binding site, and their amino acid composition, hydrophobicity, isoelectric point, etc. were consistent with the characteristics of RTX-type S-layer in bacteria.

菌落是微囊藻成为优势种群并形成花朵的关键。为了找到菌落形成的机制，我们研究了菌落和单细胞株的细胞壁结构。结果显示，通过透射电镜观察，菌落在细胞表面比单细胞菌具有显着的表层蛋白（S层）。Western印迹显示，结肠菌株比单细胞菌株具有更多的S层。当铜绿微囊藻PCC7806的S层基因（GenBank登录号CAO89090.1）表达在集胞藻属中。PCC6803，PCC6803聚集成殖民地形态。结果表明，S层可以促进微囊藻的集落形成。。根据PCC6803和PCC7806的S层序列，从GenBank中筛选了其他微囊藻菌株中的9个S层基因。序列比较表明，S层保守区均位于N端。S层包含具有Ca ²⁺结合位点的毒素重复序列（RTX），其氨基酸组成，疏水性，等电点等与细菌中RTX型S层的特征一致。