Abstract. Microorganisms collected from sediments of Ho-Tsin River in southern Taiwan were
used in this study. The ability to dechlorinate hexachlorobenzene (HCB) was induced by enrichment
incubation in yeast extract amended culture and acclimation with HCB. Addition of lactate
or replacement of yeast extract by lactate did not enhance the dechlorination ability. With strong
electron capturing capability, denitrifying bacteria resulted in complete inhibition of dechlorination
in the mixed culture contained nitrate. In the culture amended with sulfate, sulfate reducing bateria
shared electrons and nutrient with HCB-dechlorinating consortium but grabbed more electrons when
treated with vancomycin. Results from multi-factors tests indicate that the influences of factors
on dechlorination were complicated. Dechlorinating microbes, electron suppliers, sulfate reducing
bacteria and denitrifying bacteria, all possibly caused a great effect on dechlorination.
Keywords: dechlorinating microbes, denitrifying bacteria, electron suppliers, hexachlorobenzene,