Five bacterial strains were screened for polymer production in five synthetic media (GP, PS, GL, PL and PR). The highest polymer yield was obtained from Bacillus subtilis WD161 in PR medium (8.89 g/L). Cultivation at 30, 45 and 60 degrees C indicated that they were thermotolerant with the maximum biopolymer yield at 45 degrees C. Using palm oil mill effluent (POME) as medium, the nitrogen had to be supplemented to 1.28 g/L (equal to that in PR medium) with the initial pH adjusted to 7.0 and cultivation at 30 degrees C. Characterization based on its composition and functional groups revealed that the biopolymer WD161 was glycoprotein with the molecular weight of 1.54 x 10(6) Da. FT-IR analysis revealed the presence of amine (NH2), hydroxyl, carboxyl and carbonyl groups. It was also a bioflocculant and its flocculating activity to precipitate the suspended solid in POME increased by 35% under the optimum condition. (C) 2016 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.