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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

Effect of vitamin B12concentration on maximum CF transformation rates by DHM-1; B12concentrations are expressed in terms of mol B12added per mol CF initially added (CFo). The line represents the fit to equation 1.
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Figure 3: Effect of vitamin B12concentration on maximum CF transformation rates by DHM-1; B12concentrations are expressed in terms of mol B12added per mol CF initially added (CFo). The line represents the fit to equation 1.

Mentions: Reducing the molar ratio of B12 added per mole of CF added from 0.03 mol B12 per mol of CF added to 0.01 resulted in a moderate decrease in the maximum CF transformation rate, while the rate fell more quickly below 0.01 (Figure 3). Fitting the data to equation 1 resulted in a Vmax of 66 ± 4.6 mg CF/L/d and a B12/Km ratio of 0.0050 ± 0.0010 mol B12 per mol CF (±values indicate 95% confidence intervals). Assuming a yield of 50–60 mg protein/L from the single dose of corn syrup added (Shan et al. [2010a]), Vmax can be normalized to approximately 1.2 mg CF/mg protein/d.


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

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

Effect of vitamin B12concentration on maximum CF transformation rates by DHM-1; B12concentrations are expressed in terms of mol B12added per mol CF initially added (CFo). The line represents the fit to equation 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Effect of vitamin B12concentration on maximum CF transformation rates by DHM-1; B12concentrations are expressed in terms of mol B12added per mol CF initially added (CFo). The line represents the fit to equation 1.
Mentions: Reducing the molar ratio of B12 added per mole of CF added from 0.03 mol B12 per mol of CF added to 0.01 resulted in a moderate decrease in the maximum CF transformation rate, while the rate fell more quickly below 0.01 (Figure 3). Fitting the data to equation 1 resulted in a Vmax of 66 ± 4.6 mg CF/L/d and a B12/Km ratio of 0.0050 ± 0.0010 mol B12 per mol CF (±values indicate 95% confidence intervals). Assuming a yield of 50–60 mg protein/L from the single dose of corn syrup added (Shan et al. [2010a]), Vmax can be normalized to approximately 1.2 mg CF/mg protein/d.

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