| Sulfolane (tetrahydrothlophene-1,1-dioxide) is used In the Sulfinol RTM process for natural gas sweetening, which has been implemented worldwide. Sulfolane has entered groundwaters and aquifers through spills, landfills and unlined surface storage ponds. Due to Its high water solubility sulfolane poses a risk for off-site contamination.;Three sites were screened in laboratory microcosms to determine the sulfolane degradation potential in contaminated aquifer sediments. All samples; degraded sulfolane aerobically. Anaerobic sulfolane biodegradation occurred in some NO3-- and Mn(IV)-reducing microcosms.;Aerobic sulfolane biodegradation was further evaluated. Microbial communities from wetlands samples degraded sulfolane without added nutrients. Pristine aquifer sediment samples developed sulfolane-degrading communities if mixing was provided. Contaminated sediment populations that were not supplemented with nutrients eventually degraded sulfolane. Microbial communities from a contaminated aquifer were stimulated by P addition, while subsurface sediments from a different location required N supplementation. Overall, supplementation with the most limiting nutrient improved biodegradation, which was further improved by addition of the nutrient that demonstrated less importance.;A differential medium was developed to detect sulfolane degraders. Sulfolane degraders were detected by the production of acid during aerobic mineralization of the compound. Organisms that were unable to degrade sulfolane produced ammonium from tryptone. This medium was 93% accurate for distinguishing between degraders and nondegraders.;Mixed bacterial cultures converted sulfolane-C to 77% CO2, 10% biomass and 15% soluble organic compounds, and 82% of sulfolane-S to SO 4=. Pure cultures produced an average of 38% CO 2, 23% biomass, 40% soluble organic compounds and 59% SO4 = from sulfolane C and S, suggesting that some metabolites remained. These were not identified.;A sulfolane-degrading isolate was identified, using a combination of 16S rRNA sequencing, physiological traits and colony and cell morphology. This organism most closely resembled Variovorax paradoxus; it may belong to the species paradoxus, or it may represent an unidentified species in the genus Variovorax. |
