title: Toxic effects of thiol-reactive compounds on anaerobic biomass.
abstract: The objective of this study was to characterize the toxic effects of three well known thiol-reactive electrophilic compounds, N-ethylmaleimide (NEM), pentachlorophenol (PCP) and 1-chloro-2,4-dinitrobenzene (CDNB) on anaerobic biotransformation process. The work was part of a larger investigation on potassium efflux as a possible response mechanism of anaerobic microorganisms to the presence of thiol-reactive organic compounds and the interference of such compounds on the reductive dehalogenation process. Using anaerobic toxicity assay (ATA) and granular anaerobic biomass from a full-scale upflow anaerobic sludge blanket (UASB) reactor, inhibitory concentrations of these compounds that reduced the microbial activity of granular biomass to 50% of a control (IC50) were determined to be 592, 0.97, and 450 mg/l for NEM, PCP, and CDNB, respectively. Toxicity of NEM was also tested on anaerobic biomass from a municipal wastewater treatment plant digester and slightly lower IC50 of 532 mg/l was obtained. The results presented here indicate that anaerobic biomass can acclimate to the three thiol-reactive compounds studied and recover from inhibition as long as the toxicant concentration is below a threshold level. That threshold concentration was found to be 500 mg/l for NEM on biomass from the municipal digester, 1 mg/l for PCP, and 500 mg/l for CDNB, both on granular biomass. Granular anaerobic biomass showed recovery even at NEM concentrations of 1000 mg/l.
authors.affiliation: Villanova University, Department of Civil and Environmental Engineering, Villanova, PA 19085, USA.
authors.forename: Nalan
authors.initials: N
authors.lastname: Tepe
authors.forename: Leah A
authors.initials: LA
authors.lastname: Shimko
authors.forename: Metin
authors.initials: M
authors.lastname: Duran
mesh_terms: D001421:Bacteria, Anaerobic / Q000187:drug effects*; D001711:Biotransformation; D004787:Environmental Pollution / Q000517:prevention & control*; D005033:Ethylmaleimide / Q000633:toxicity*; D020128:Inhibitory Concentration 50; D010416:Pentachlorophenol / Q000633:toxicity*; D010853:Picryl Chloride / Q000633:toxicity*; D013439:Sulfhydryl Reagents / Q000633:toxicity*; D018675:Toxicity Tests
chemical_list: D013439:Sulfhydryl Reagents; D010416:Pentachlorophenol; D005033:Ethylmaleimide; D010853:Picryl Chloride