Revealing a novel natural bioflocculant resource from Ruditapes philippinarum: Effective polysaccharides and synergistic flocculation

A novel natural bioflocculant resource of Ruditapes philippinarum conglutination mud (RPM) with the effective flocculation components was firstly reported in this study. Experimental results showed that the maximum flocculation activity (FR) of RPM to kolin clay reached 86.7% in deionized water assay system and 91.8% in sea water assay system. RPM could flocculate marine microalgae Chlorella salina with a FR of 74.1%. The crude RPM polysaccharides extract(RPMP) were composed of 97.8% (w/w) polysaccharides and 2.2% (w/w) protein and the functional components of pure RPMP were firstly discovered to be two complex heteropolysaccharides of RPMP-1 and RPMP-2 with similar monosaccharides composition except glucose content. The molecular weights of RPMP-1 and RPMP-2 were 5.7 kDa and 18.0 kDa, respectively. It is interesting to find that RPMP-1 and RPMP-2 exhibited synergistic flocculation activity of 65.6% at a mass ratio of 2:1 as in crude RPMP, suggesting the original proportion is significant to synergistic flocculation.