The effect of different carbon sources on the starting-up duration of sulfidogenic bioreactor and corresponding bacterial communities were investigated. The bioreactor starting-up duration was closely dependent on the complexity and availability of the carbon sources. 16S rRNA gene diversity of climax bacterial communities developed in each bioreactor had an increasing tendency for the carbon resource of lactate, acetate/ethanol, glucose and molasses. At the steady stage of bioreactors, the molasses-fed bacterial community pattern grouped with that of glucose-fed and acetate/ethanol-fed grouped with that of lactate-fed, both of which separated each other and departed further from the seed sludge. The present Study concludes that utilization of simple carbon sources that are readily utilized by sulfate-reducing bacteria (SRB) can not only increase the fraction of SRB and thus improve sulfate removal efficiency, but also shorten the starting-up duration. (C) 2009 Elsevier Ltd. All rights reserved.