The light- and electron-microscopic analysis of the colonies of a bacterial consortium capable of utilizing alkylsulfonates, which are the main ingredients of sewage from the synthetic rubber industry, revealed the presence of eight types of cells. All types of cells were gram-negative and differed in shape, size, and the presence of capsule and cytoplasmic inclusions. Three types of cells were present in all the colonies that were studied. The presence of the other types of cells depended on the inoculum used and on the composition of the growth medium.