Cyanocobalamin Enables Activated Sludge Bacteria to Dechlorinate Hexachloro-1,3-butadiene to Nonchlorinated Gases

• Published in: Bioremediation journal Vol. 12; no. 4; pp. 177 - 184
• Main Authors: James, D. L., Cord-Ruwisch, R., Schleheck, D., Lee, M. J., Manefield, M.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.10.2008; Taylor & Francis; Taylor & Francis Ltd
• Subjects: 1,3-butadiene; 1,3-butadiyne; 1-buten-3-yne; activated sludge; Bacteria; Biodegradation of pollutants; Biological and medical sciences; Bioremediation; Biotechnology; cyanocobalamin; Environment and pollution; Fundamental and applied biological sciences. Psychology; Gases; hexachloro-1,3-butadiene (HCBD); Industrial applications and implications. Economical aspects; Pollutants; reductive dechlorination; Sludge; Water treatment; Water treatment plants; USA, Connecticut, Hartford Basin, Newark Supergroup, Shuttle; Activated sludge; Dechlorination; 1-buten-3-yne; cyanocobalamin; reductive dechlorination; Bacteria; 1,3-butadiyne; Bioremediation; hexachloro-1,3-butadiene (HCBD); 1,3-butadiene
• ISSN: 1088-9868; 1547-6529
• DOI: 10.1080/10889860802477085

The ability of activated sludge obtained from a local wastewater treatment plant to dechlorinate hexachloro-1,3-butadiene (HCBD) in the presence of either acetate or lactate and cyanocobalamin was investigated. Results from headspace analysis indicated complete dechlorination of HCBD by the accumulation of fully dechlorinated C4 gases (1-buten-3-yne, 1,3-butadiene, and 1,3-butadiyne). Dechlorination products were not observed in the control cultures without cyanocobalamin. Examination of control cultures revealed that the disappearance of HCBD from the headspace was partly due to adsorption into the biomass. However, the key for dechlorination was the shuttle (cyanocobalamin) rather than specific microbial enzymatic activity. The hypothesis that the bacteria reduced cyanocobalamin, which in turn reductively dechlorinated HCBD, was supported by the finding that cyanocobalamin reduced by zero-valent zinc resulted in complete dechlorination. The significance of the findings is that, in contrast to prior work where specific anaerobic bacteria (enrichments or pure cultures) were believed to be necessary for dechlorination resulting in only partly dechlorinated products, the currect data show that nonspecific aerobic activated sludge bacteria can be employed for complete HCBD dechlorination at rates sufficiently high to be considered for bioremediation projects.