Flocculent activity of a recombinant protein from Moringa oleifera Lam. seeds

Seeds of the tropical tree Moringa oleifera contain small storage proteins able to flocculate particles in suspension in water. The cDNA encoding one of these flocculent proteins, MO2.1, was cloned and the recombinant protein was expressed in Escherichia coli. The flocculent activity of the purified recombinant MO2.1 was assayed on clays and bacteria using light and confocal microscopy and GFP-overexpressing bacteria. We show that MO2.1 is able to aggregate montmorillonite clay particles as well as gram-positive and gram-negative bacteria. We discuss the use of recombinant proteins to study flocculating properties and improve water purification processes.