Isolation and characterization of temperature and alkaline stable bioflocculant from Agrobacterium sp M-503

A bacterium isolated from activated sludge of propylene epoxide wastewater was identified as Agrobacterium sp M-503 It was confirmed to produce bioflocculant with excellent flocculation activity The yield of the bioflocculant reached 14 9 g/l in batch cultivation with a carbon source conversion of 74 5% This bioflocculant was temperature and alkaline stable, retaining almost all flocculation activity after being treated at 121 degrees C for 20 minutes or at pH 12 0 It consisted of neutral sugar, uronic acid, aminosugar and protein in weight ratios of 85 0 9 9 2 1 3 0 The active polysaccharide fraction of the bioflocculant was purified to homogeneity by ethanol precipitation, DEAE ion-exchange and gel chromatography Analysis of the purified polysaccharide showed that it consisted of glucose residues and had a molecular weight of 8 1 x 10(4) Da Its low molecular weight endowed it with excellent solubility and favorable flocculation activity, especially 1 or small particulates