Screening of nanobody against Microcystis from a human phage display nanobody library

Microcystis species identification is essential for ecological studies and water bloom control. Immunoassays are more specific and convenient and several approaches have been used to develop for diagnosing harmful red tide algae. However, investigations on Microcystis identification using immunological approaches are still in the initial stage. In this study, Microcystis aeruginosa PCC7806 lysates were utilized as coated antigens to enrich and screen specific Microcystis nanobodies from a human domain antibody display library. After three rounds of enrichment, 10 positive monoclonal particles were isolated from the library and the most two positive nanobodies (DAb2 and Dab3) were effectively produced in Escherichia coli BL21. Finally, the DAb2 showed specific immune binding to different Microcystis by the immuno-dot blot assay. This antibody could be used to establish an immunological method to identify Microcystis .