A differential medium for the isolation and enumeration of sulfolane-degrading bacteria

A differential medium for the detection of tetrahydrothiophene-l,l-dioxide (sulfolane)-degrading bacteria was developed. The basis of differentiation is pH; aerobic sulfolane biodegradation results in the production of acid. The medium contained 2.3 g of Plate Count Agar, 17 g of agar, 0.1 g of bromthymol blue and 1 g of sulfolane per litre of water. Agar plates were green. Bacterial growth resulted in the production of a blue colour; a yellow halo developed around colonies that used sulfolane. The sulfolane biodegradation abilities of 271 colonies isolated from the differential agar were tested in liquid medium with sulfolane as a sole carbon and sulfur source. Of 135 colonies that produced yellow halos (indicating sulfolane consumption on the plates), 93% degraded sulfolane in liquid culture. Of 136 colonies that did not produce yellow halos, 93% did not degrade sulfolane in liquid culture. This new medium was useful for the isolation and enumeration of sulfolane-degrading bacteria. (C) 1998 Elsevier Science B.V. All rights reserved.