The Impact of Carbon Tetrachloride on an Anaerobic Methanol-Degrading Microbial Community

Abstract

The evolution of microbial communities with increasing carbon tetrachloride concentrations was studied in two anaerobic columns containing sand and two different clay soils, one of which contained high levels of iron. Microbial communities were characterized through analysis of column effluents with denaturing gradient gel electrophoresis and quantitative polymerase chain reaction for archaea and eubacteria as inlet carbon tetrachloride concentrations were increased from 0.8 to 29 μM. Inhibition of microbial activity was observed in both columns, and was associated with the accumulation of chloroform at concentrations of 0.2 to 0.4 μM as inlet CT concentrations were increased to 2.4-3.0 μM in the low-iron clay column and approximately 16 μM in the iron rich clay column. Inhibition was indicated by decreasing rates of methanol and carbon tetrachloride degradation, decreases in effluent levels of DNA, and shifts in microbial communities of the columns. Even with the inhibition observed, in the iron-rich clay column CT degradation continued to the end of the study with inlet CT concentrations of 29 μM, in contrast to the low-iron clay column in which minimal CT degradation occurred once CT inlet concentrations exceeded 3 μM. The greater capacity for CT degradation in the column containing the ironrich clay was hypothesized to be the result of reaction with biogenic ferrous iron produced by biological dissimilatory iron reduction.

Temporal hydrochemical and microbial variations in microcosm experiments from sites contaminated with chloromethanes under biostimulation with lactic acid

“…As for CF, albeit our data showed biotic degradation of CF in support of previous studies (e.g., Ciavarelli et al, 2012;Chan et al, 2012, Lee et al, 2012, Lima and Sleep, 2010, the δ 13 C of CF did not vary substantially (Figure 2). This led to the lack of isotopic fractionation, which differs from the observations of Chan et al (2012) who, in contrast to us, used CF as the only parent compound susceptible to undergo isotopic fractionation as it biodegraded.…”

Vitamin B12 effects on chlorinated methanes-degrading microcosms: Dual isotope and metabolically active microbial populations assessment

“…Lima and Sleep 400 (2010) reported inhibition of the microbial activity related to CT degradation by 0.2-0.4 μM of 401 CF. The authors observed a decrease in the number of bacterial species, including Acidovorax, close to those considered inhibitory in the reported study byLima and Sleep (2010), which 404 supports that the lowering of δ 13 CCT enrichment after 211 days in the CTw/oB treatment (Fig. 4052C,D) might be due to the toxic effects of CF accumulation(Fig.…”

Use of dual element isotope analysis and microcosm studies to determine the origin and potential anaerobic biodegradation of dichloromethane in two multi-contaminated aquifers

“…In PZ-19, however, lactate was not completely consumed but, in both bioaugmentation tests, its decrease was followed by acetate and propionate production (SI section K). The inability of inoculated bacteria to efficiently degrade contaminants in these microcosms suggested that there were inhibition issues, possibly due to the presence of co-contaminants in groundwater such as CT, which is a known inhibitor of the microbial activity and CF degradation in particular (section 2.2) (da Lima and Sleep, 2010;Grostern et al, 2010;Justicia-Leon et al, 2014;Wei et al, 2016). The results obtained with the microcosms suggested that, under the studied conditions, degradation of contaminants was very slow and inefficient, but possible to some extent, which agreed with the information obtained from the isotopic field data that was discussed above.…”

“…In addition, it has also been reported that CT and CF inhibit their mutual biodegradation (da Lima and Sleep, 2010;Grostern et al, 2010;Justicia-Leon et al, 2014).…”