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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

CF degradation with different inoculum levels of DHM-1 (percent by volume, indicated by the number after the treatment letter). Treatments A through E contained DHM-1, corn syrup (CS) and B12 (3 mol% of CF). Treatments F through I were abiotic controls. Error bars show standard deviations of triplicate bottles.
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Figure 5: CF degradation with different inoculum levels of DHM-1 (percent by volume, indicated by the number after the treatment letter). Treatments A through E contained DHM-1, corn syrup (CS) and B12 (3 mol% of CF). Treatments F through I were abiotic controls. Error bars show standard deviations of triplicate bottles.

Mentions: Biodegradation of CF proceeded at a high rate even at a DHM-1 inoculum level as low as 10−8 percent (v/v) (Figure 5, treatments A-E). The 5% inoculum (v/v) corresponds to a protein concentration of approximately 5 mg/L, so the 10−8 inoculum equates to approximately 10-8 mg/L. Headspace monitoring continued until CF fell below the maximum contaminant level (MCL) for trihalomethanes (80 μg/L). At a 5% inoculum inoculum level, 23 days of incubation was required, while 39 days was required for the 10−8% inoculum level. Correspondingly, the maximum initial degradation rate was approximately twice as high at the highest inoculum (30 mg/L/d) compared to the lowest (17 mg/L/d). Accumulation of DCM and CM amounted to less than 0.6% of the CF consumed. Losses from uninoculated controls (treatments F-I) were comparatively minor. These results demonstrate the potential for DHM-1 to biodegrade high concentrations of CF even at a low initial cell density, which is an essential characteristic for use in bioaugmentation.


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

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

CF degradation with different inoculum levels of DHM-1 (percent by volume, indicated by the number after the treatment letter). Treatments A through E contained DHM-1, corn syrup (CS) and B12 (3 mol% of CF). Treatments F through I were abiotic controls. Error bars show standard deviations of triplicate bottles.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: CF degradation with different inoculum levels of DHM-1 (percent by volume, indicated by the number after the treatment letter). Treatments A through E contained DHM-1, corn syrup (CS) and B12 (3 mol% of CF). Treatments F through I were abiotic controls. Error bars show standard deviations of triplicate bottles.
Mentions: Biodegradation of CF proceeded at a high rate even at a DHM-1 inoculum level as low as 10−8 percent (v/v) (Figure 5, treatments A-E). The 5% inoculum (v/v) corresponds to a protein concentration of approximately 5 mg/L, so the 10−8 inoculum equates to approximately 10-8 mg/L. Headspace monitoring continued until CF fell below the maximum contaminant level (MCL) for trihalomethanes (80 μg/L). At a 5% inoculum inoculum level, 23 days of incubation was required, while 39 days was required for the 10−8% inoculum level. Correspondingly, the maximum initial degradation rate was approximately twice as high at the highest inoculum (30 mg/L/d) compared to the lowest (17 mg/L/d). Accumulation of DCM and CM amounted to less than 0.6% of the CF consumed. Losses from uninoculated controls (treatments F-I) were comparatively minor. These results demonstrate the potential for DHM-1 to biodegrade high concentrations of CF even at a low initial cell density, which is an essential characteristic for use in bioaugmentation.

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