Production of an extracellular polysaccharide bioflocculant by Klebsiella pneumoniae

Klebsiella pneumoniae H12 produced a newly identified extracellular polysac charide in an ethanol medium with a yield of 3.0 g/l. The molar composition of the polysaccharide was 56.04% galactose, 25.92% glucose, 10.92% glucuro nic acid, 3.71% mannose, and 3.37% glucuronic acid. The addition of 0.5%-1. 5% NaCl increased production. The polysaccharide flocculated with kaolin cl ay in suspension at the concentration of 1 ppm in a 300-ppm solution of CaC l2. Almost all bacterial species cells aggregated in the polysaccharide sol ution. The ability to flocculate with kaolin clay changed with the pH and w ith the concentrations of coexisting cation and anion species. The polysacc haride flocculant mag participate in in vivo bacterial aggregation or adher ence to host organisms.