A strain (designated DP-152) which produces an excellent flocculating substance was isolated from soil samples and identified as Bacillus species. The major flocculating substance (bioflocculant DP-152) produced by Bacillus sp. DP-152 was purified by ethanol precipitation and cetylpyridinium chloride (CPC) precipitation and gel permeation chromatography. In kaolin suspension, the highest flocculating activity was obtained at the bioflocculant concentration of 1 mg/l. The bioflocculant DP-152, which has an estimated molecular weight of over 2 x 10(6) daltons, is a novel bioflocculant derived from sugar components consisting of glucose, mannose, galactose, and fucose in an approximate molar ratio of 8:4:2:1. Some of its physico-chemical properties were also determined.