Limits...
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

Transformation of (a) CT; (b) CFC-11; and (c) CF, by DHM-1 in MSM with corn syrup and B12added. LC = live control (DHM-1 with corn syrup but without B12); MC + B12 = media control with B12. Daughter products are shown only for the DHM-1 + B12 treatments. ↓ = addition of corn syrup; B12 was added only at t = 0. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols. The initial increase in CFC-11 was likely due to insufficient time to establish equilibrium at time zero between the headspace and liquid phases.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4230812&req=5

Figure 1: Transformation of (a) CT; (b) CFC-11; and (c) CF, by DHM-1 in MSM with corn syrup and B12added. LC = live control (DHM-1 with corn syrup but without B12); MC + B12 = media control with B12. Daughter products are shown only for the DHM-1 + B12 treatments. ↓ = addition of corn syrup; B12 was added only at t = 0. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols. The initial increase in CFC-11 was likely due to insufficient time to establish equilibrium at time zero between the headspace and liquid phases.

Mentions: When provided with corn syrup and B12, DHM-1 readily biodegraded CT, CFC-11, and CF (Figure 1). Average transformation rates [i.e., (initial concentration)/(time to reach the detection limit)] were 1.3, 0.54, and 22 mg/L/d for CT, CFC-11, and CF, respectively. Reductive dehalogenation products (i.e., CF, DCM and CM from CT; HCFC-21 from CFC-11; and DCM and CM from CF) at the end of the incubation period represented 6% or less of CFC-11 and 1% percent of CT and CF. CS2 accounted for 5-16% of the CT consumed, indicating a substitutive pathway was involved. Over a 14 day period, approximately 20% of the initial CT was consumed in the media + B12 treatment. No losses occurred in the live control (i.e., DHM-1 with corn syrup but without B12) or in media without B12 (Additional file 1: Figure S1), indicating that abiotic transformation of CT in MSM was mediated by B12. Biotransformation of CFC-11 started after a lag of approximately 10 days and was complete by day 48 (Figure 1b). Approximately equal amounts of HCFC-21 and CS2 (i.e., 3 μmol/bottle each) accumulated, while formation of HCFC-31 was negligible. Only a minor amount of CFC-11 transformation occurred in the live control and media + B12 control. No transformation of CFC-11 occurred in the MSM control without B12 (Additional file 1: Figure S1). Biotransformation of CF (513 mg/L) occurred only in the live treatment with DHM-1, corn syrup, and B12; none was observed in the live control, media + B12 control, or in the media without B12 control (Additional file 1: Figure S1). Methane formation was absent in all treatments.


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

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

Transformation of (a) CT; (b) CFC-11; and (c) CF, by DHM-1 in MSM with corn syrup and B12added. LC = live control (DHM-1 with corn syrup but without B12); MC + B12 = media control with B12. Daughter products are shown only for the DHM-1 + B12 treatments. ↓ = addition of corn syrup; B12 was added only at t = 0. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols. The initial increase in CFC-11 was likely due to insufficient time to establish equilibrium at time zero between the headspace and liquid phases.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Transformation of (a) CT; (b) CFC-11; and (c) CF, by DHM-1 in MSM with corn syrup and B12added. LC = live control (DHM-1 with corn syrup but without B12); MC + B12 = media control with B12. Daughter products are shown only for the DHM-1 + B12 treatments. ↓ = addition of corn syrup; B12 was added only at t = 0. Error bars are the data range for duplicate bottles; when not visible, the bars are smaller than the symbols. The initial increase in CFC-11 was likely due to insufficient time to establish equilibrium at time zero between the headspace and liquid phases.
Mentions: When provided with corn syrup and B12, DHM-1 readily biodegraded CT, CFC-11, and CF (Figure 1). Average transformation rates [i.e., (initial concentration)/(time to reach the detection limit)] were 1.3, 0.54, and 22 mg/L/d for CT, CFC-11, and CF, respectively. Reductive dehalogenation products (i.e., CF, DCM and CM from CT; HCFC-21 from CFC-11; and DCM and CM from CF) at the end of the incubation period represented 6% or less of CFC-11 and 1% percent of CT and CF. CS2 accounted for 5-16% of the CT consumed, indicating a substitutive pathway was involved. Over a 14 day period, approximately 20% of the initial CT was consumed in the media + B12 treatment. No losses occurred in the live control (i.e., DHM-1 with corn syrup but without B12) or in media without B12 (Additional file 1: Figure S1), indicating that abiotic transformation of CT in MSM was mediated by B12. Biotransformation of CFC-11 started after a lag of approximately 10 days and was complete by day 48 (Figure 1b). Approximately equal amounts of HCFC-21 and CS2 (i.e., 3 μmol/bottle each) accumulated, while formation of HCFC-31 was negligible. Only a minor amount of CFC-11 transformation occurred in the live control and media + B12 control. No transformation of CFC-11 occurred in the MSM control without B12 (Additional file 1: Figure S1). Biotransformation of CF (513 mg/L) occurred only in the live treatment with DHM-1, corn syrup, and B12; none was observed in the live control, media + B12 control, or in the media without B12 control (Additional file 1: Figure S1). Methane formation was absent in all treatments.

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