Abstract: The polysaccharide released from the unicellular cyanobacterium Cyanothece sp. CCY 0110 exhibits low cytotoxicity and proves to be suitable for the delivery of macromolecules. The cyanobacterium extracellular polymer disclosed in the present subject-matter, namely a polysaccharide and more in particular an heteropolysaccharide, assembles with proteins into a new phase with gel-like behaviour and the release kinetics can be modulated (i.e., delayed) by adding divalent cations and/or also exhibits physical and chemical properties typical of a bioemulsifier or a bioflocculant.