Abstract: A nonpathogenic stenotrophomonas strain USTB2 was screened out from the soil of Sijiaying iron ore plant and studied as collector for hematite by flotation tests. Zeta potential measurement results showed that the bacteria was negatively charged in the large range of pH. The contact angle of hematite increased by 3395° and surface hydrophobicity of hematite was greatly improved after interaction with USTB2 strain. The flotation recovery of hematite could reach to 7631% at pH=6 and the bacterial cells addition amount of 60g/t. The mechanism study results showed that the outer surface of USTB2 cell has hydrocarbon groups， carboxyl groups and phosphoric acid groups， so the bacteria has similar characteristics of fatty acid collector， and can form the flocs between hematitehematite particles by the “bridge” action. This is confirmed that the stenotrophomonas strain USTB2 can work as collector for hematite.

Key words: stenotrophomonas strain USTB2, hematite, flotation, collector, floc