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Biodegradation of high concentrations of halomethanes by a fermentative enrichment culture.

Shan H, Wang H, Yu R, Jacob P, Freedman DL - AMB Express (2014)

Bottom Line: CT (15 mg/L) and CFC-11 (25 mg/L) were also biodegraded without significant accumulation of halomethane daughter products.The highest rate of CF biodegradation occurred at pH 7.7; activity decreased substantially below pH 6.0.Overall, the results suggest that DHM-1 may be effective for bioaugmentation in source zones contaminated with thousands of milligrams per liter of CF and tens of milligrams per liter of CT and CFC-11.

View Article: PubMed Central - HTML - PubMed

Affiliation: PeroxyChem Environmental Solutions (East Asia), Room 5B16, West Wing, Hanwei Plaza, 7 Guanghua Road, Chaoyang District, Beijing 100004, China.

ABSTRACT
A fermentative enrichment culture (designated DHM-1) that grows on corn syrup was evaluated for its ability to cometabolically biodegrade high concentrations of chloroform (CF), carbon tetrachloride (CT), and trichlorofluoromethane (CFC-11). When provided with corn syrup and vitamin B12 (0.03 mol B12 per mol CF), DHM-1 grew and biodegraded up to 2,000 mg/L of CF in 180 days, with only minor transient accumulation of dichloromethane and chloromethane. CT (15 mg/L) and CFC-11 (25 mg/L) were also biodegraded without significant accumulation of halomethane daughter products. The rate of CF biodegradation followed a Michaelis-Menten-like pattern with respect to the B12 concentration; one-half the maximum rate (66 mg CF/L/d) occurred at 0.005 mol B12 per mol CF. DHM-1 was able to biodegrade 500 mg/L of CF at an inoculum level as low as 10(-8) mg protein/L. The highest rate of CF biodegradation occurred at pH 7.7; activity decreased substantially below pH 6.0. DHM-1 biodegraded mixtures of CT, CFC-11, and CF, although CFC-11 inhibited CF biodegradation. Evidence for compete defluorination of CFC-11 was obtained based on a fluoride mass balance. Overall, the results suggest that DHM-1 may be effective for bioaugmentation in source zones contaminated with thousands of milligrams per liter of CF and tens of milligrams per liter of CT and CFC-11.

No MeSH data available.


Related in: MedlinePlus

Performance of DHM-1 in transforming mixtures of (a) CT + CF; (b) CFC-11 + CF; and (c) CT + CFC-11 in MSM, with corn syrup and B12added (t = 0). Arrows indicate addition of corn syrup. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols.
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Figure 6: Performance of DHM-1 in transforming mixtures of (a) CT + CF; (b) CFC-11 + CF; and (c) CT + CFC-11 in MSM, with corn syrup and B12added (t = 0). Arrows indicate addition of corn syrup. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols.

Mentions: In the presence of 12 mg/L CT (13 μmol/bottle) and 512 mg/L CF (463 μmol/bottle), DHM-1 biodegraded both halomethanes simultaneously, with no apparent effect of CT on CF or vice versa (Figure 6a). A low amount of CS2 (5.2 μmol/bottle) accumulated, accounting for 1% of the CT + CF transformed. Formation of DCM (0.6 μmol/bottle) was negligible. With a mixture of 23 mg/L CFC-11 (55 μmol/bottle) and 509 mg/L CF (461 μmol/bottle), DHM-1 biodegraded CFC-11 faster than when CFC-11 was added individually (Figure 1b versus 6b), possibly related to changes in membrane fluidity or homeoviscous and homeophasic adaptation during growth in the presence of a high concentration of CF (Shan et al. [2010a]). In contrast, CF transformation was inhibited by the presence of CFC-11; CF transformation did not begin until the concentration of CFC-11 dropped to 6 mg/L (14 μmol/bottle) on day 18. Minor amounts of CS2, DCM and HCFC-21 accumulated in comparison to the amount of halomethanes removed. With a mixture of 16 mg/L CT (17 μmol/bottle) and 24 mg/L CFC-11 (57 μmol/bottle), CT was consumed in 10 days; following a lag phase of approximately 10 days, CFC-11 was consumed by day 47 (Figure 6c). These patterns are similar to what occurred with the individual compounds, indicating no apparent interaction between CT and CFC-11. The combination of CT and CFC-11 resulted in more CS2 accumulation than the other two-component mixtures, accounting for 7.7% of the CT and CFC-11 transformed. Formation of HCFC-21 was also slightly higher than in the mixture of CFC-11 and CF, while formation of DCM was negligible.


Biodegradation of high concentrations of halomethanes by a fermentative enrichment culture.

Shan H, Wang H, Yu R, Jacob P, Freedman DL - AMB Express (2014)

Performance of DHM-1 in transforming mixtures of (a) CT + CF; (b) CFC-11 + CF; and (c) CT + CFC-11 in MSM, with corn syrup and B12added (t = 0). Arrows indicate addition of corn syrup. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230812&req=5

Figure 6: Performance of DHM-1 in transforming mixtures of (a) CT + CF; (b) CFC-11 + CF; and (c) CT + CFC-11 in MSM, with corn syrup and B12added (t = 0). Arrows indicate addition of corn syrup. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols.
Mentions: In the presence of 12 mg/L CT (13 μmol/bottle) and 512 mg/L CF (463 μmol/bottle), DHM-1 biodegraded both halomethanes simultaneously, with no apparent effect of CT on CF or vice versa (Figure 6a). A low amount of CS2 (5.2 μmol/bottle) accumulated, accounting for 1% of the CT + CF transformed. Formation of DCM (0.6 μmol/bottle) was negligible. With a mixture of 23 mg/L CFC-11 (55 μmol/bottle) and 509 mg/L CF (461 μmol/bottle), DHM-1 biodegraded CFC-11 faster than when CFC-11 was added individually (Figure 1b versus 6b), possibly related to changes in membrane fluidity or homeoviscous and homeophasic adaptation during growth in the presence of a high concentration of CF (Shan et al. [2010a]). In contrast, CF transformation was inhibited by the presence of CFC-11; CF transformation did not begin until the concentration of CFC-11 dropped to 6 mg/L (14 μmol/bottle) on day 18. Minor amounts of CS2, DCM and HCFC-21 accumulated in comparison to the amount of halomethanes removed. With a mixture of 16 mg/L CT (17 μmol/bottle) and 24 mg/L CFC-11 (57 μmol/bottle), CT was consumed in 10 days; following a lag phase of approximately 10 days, CFC-11 was consumed by day 47 (Figure 6c). These patterns are similar to what occurred with the individual compounds, indicating no apparent interaction between CT and CFC-11. The combination of CT and CFC-11 resulted in more CS2 accumulation than the other two-component mixtures, accounting for 7.7% of the CT and CFC-11 transformed. Formation of HCFC-21 was also slightly higher than in the mixture of CFC-11 and CF, while formation of DCM was negligible.

Bottom Line: CT (15 mg/L) and CFC-11 (25 mg/L) were also biodegraded without significant accumulation of halomethane daughter products.The highest rate of CF biodegradation occurred at pH 7.7; activity decreased substantially below pH 6.0.Overall, the results suggest that DHM-1 may be effective for bioaugmentation in source zones contaminated with thousands of milligrams per liter of CF and tens of milligrams per liter of CT and CFC-11.

View Article: PubMed Central - HTML - PubMed

Affiliation: PeroxyChem Environmental Solutions (East Asia), Room 5B16, West Wing, Hanwei Plaza, 7 Guanghua Road, Chaoyang District, Beijing 100004, China.

ABSTRACT
A fermentative enrichment culture (designated DHM-1) that grows on corn syrup was evaluated for its ability to cometabolically biodegrade high concentrations of chloroform (CF), carbon tetrachloride (CT), and trichlorofluoromethane (CFC-11). When provided with corn syrup and vitamin B12 (0.03 mol B12 per mol CF), DHM-1 grew and biodegraded up to 2,000 mg/L of CF in 180 days, with only minor transient accumulation of dichloromethane and chloromethane. CT (15 mg/L) and CFC-11 (25 mg/L) were also biodegraded without significant accumulation of halomethane daughter products. The rate of CF biodegradation followed a Michaelis-Menten-like pattern with respect to the B12 concentration; one-half the maximum rate (66 mg CF/L/d) occurred at 0.005 mol B12 per mol CF. DHM-1 was able to biodegrade 500 mg/L of CF at an inoculum level as low as 10(-8) mg protein/L. The highest rate of CF biodegradation occurred at pH 7.7; activity decreased substantially below pH 6.0. DHM-1 biodegraded mixtures of CT, CFC-11, and CF, although CFC-11 inhibited CF biodegradation. Evidence for compete defluorination of CFC-11 was obtained based on a fluoride mass balance. Overall, the results suggest that DHM-1 may be effective for bioaugmentation in source zones contaminated with thousands of milligrams per liter of CF and tens of milligrams per liter of CT and CFC-11.

No MeSH data available.


Related in: MedlinePlus