Heterologous expression of cellular adhesion molecules

A transgenic unicellular photosynthetic organism chosen from Chlamydomonas spp, and Dunaliella spp., having a DNA construct stably integrated into the unicellular photosynthetic organism's genome under conditions suitable for expression of said DNA construct in an extracellular matrix, cell wall, plasma membrane or outer membrane of said unicellular photosynthetic organism, wherein said DNA construct comprises a promoter, wherein said promoter is operably linked to a cell adhesion protein coding sequence, wherein said cell adhesion protein coding sequence is chosen from an Algal-CAM protein, an ISG protein, a V1 protein, a V2 protein, a cadherin protein and a claudin protein wherein said cell adhesion protein coding sequence is expressed as a heterologous protein in the extracellular matrix, cell wall, plasma membrane or outer membrane of the organism, and wherein the expressed cell adhesion protein induces the unicellular photosynthetic organism to flocculate by adhering to one or more unicellular photosynthetic organisms.