Physiological and biochemical characterization of the three bacterial strains was carried out according to known procedures (Dong and Cai,2001; Holt et al., 1994). There are obvious differences in the physiological and biochemical characteristics of the three bacteria (Table 1). The strains were identified as Stenotrophomonas(S.)acidaminiphilasp.,P.aeruginosasp. and Delftia(D.)tsuruhatensissp. Strain 9# was able to grow at 42 °C, but not at 4 °C, which is a distinguishing feature of P.aeruginosa