Tolerance of Anaerobic Bacteria to Chlorinated Solvents

Abstract

The aim of this research was to evaluate the effects of four chlorinated aliphatic hydrocarbons (CAHs), perchloroethene (PCE), carbon tetrachloride (CT), chloroform (CF) and 1,2-dichloroethane (1,2-DCA), on the growth of eight anaerobic bacteria: four fermentative species (Escherichia coli, Klebsiella sp., Clostridium sp. and Paenibacillus sp.) and four respiring species (Pseudomonas aeruginosa, Geobacter sulfurreducens, Shewanella oneidensis and Desulfovibrio vulgaris). Effective concentrations of solvents which inhibited growth rates by 50% (EC50) were determined. The octanol-water partition coefficient or log Po/w of a CAH proved a generally satisfactory measure of its toxicity. Most species tolerated approximately 3-fold and 10-fold higher concentrations of the two relatively more polar CAHs CF and 1,2-DCA, respectively, than the two relatively less polar compounds PCE and CT. EC50 values correlated well with growth rates observed in solvent-free cultures, with fast-growing organisms displaying higher tolerance levels. Overall, fermentative bacteria were more tolerant to CAHs than respiring species, with iron- and sulfate-reducing bacteria in particular appearing highly sensitive to CAHs. These data extend the current understanding of the impact of CAHs on a range of anaerobic bacteria, which will benefit the field of bioremediation.

Survivability of Microbes in Natural Environments and Their Ecological Impacts

“…Various approaches have been conducted to estimate the minimal maintenance energy in stable and nutrient-limited environments ( 9 ). Koenig et al indicated an energy requirement for response to stresses, because bacterial cells under lower energy-producing conditions were more sensitive to toxic solvents ( 18 ). In contrast, photosynthetic energy production in the light increased the viability of photosynthetic bacteria under nutrient-limited conditions ( 7 , 15 , 35 ).…”

Biodegradation Kinetics of 1,4-Dioxane in Chlorinated Solvent Mixtures

“…Chlorinated organic solvents are known to inhibit bacterial growth rates, − reduce membrane permeability, and damage nucleic acids . In studies using pure and mixed methanotrophic cultures, TCE exposure slowed both the metabolic and the cometabolic biotransformation rates of methane and dichloroethenes, respectively. , Chlorinated solvents have been reported to inactivate specific enzymes, such as cytochrome P450 related monoxygenases .…”

Relative Contributions of Dehalobacter and Zerovalent Iron in the Degradation of Chlorinated Methanes

“…1 Organochlorine solvents are inhibitory to most anaerobic microbial processes with inhibitory potency increasing with decreasing water solubility. 2 Further, chlorinated methanes are inhibitory to microbial organohalide respiration of chlorinated ethanes and ethanes, 3,4 which can confound attempts to bioremediate sites polluted with solvent mixtures. In such a scenario, pretreatment to remove chlorinated methanes maybe necessary or an abiotic strategy maybe employed.…”