Methanol Suppression of Trichloroethylene Degradation byMethylosinus trichosporium (OB3b) and Methane-Oxidizing Mixed Cultures
Department of Microbiology, University of Tennessee, Knoxville 37996.Applied Biochemistry and Biotechnology (Impact Factor: 1.74). 02/1991; 28-29(1):887-99. DOI: 10.1007/BF02922658
The effect of methanol on trichloroethylene (TCE) degradation by mixed and pure methylotrophic cultures was examined in batch culture experiments. Methanol was found to relieve growth inhibition of Methylosinus trichosporium (OB3b) at high (14 mg/L) TCE concentrations. Degradation of TCE was determined by both radiolabeling and gas chromatography techniques. When cultures were grown on methanol over 10 to 14 d with 0.3 mg/L TCE, OB3b degraded 16.89 +/- 0.82% (mean +/- SD) of the TCE, and a mixed culture (DT type II) degraded 4.55 +/- 0.11%. Mixed culture (JS type I) degraded 4.34 +/- 0.06% of the TCE. When grown on methane with 0.3 mg/L TCE, 32.93 +/- 2.01% of the TCE was degraded by OB3b, whereas the JS culture degraded 24.3 +/- 1.38% of the TCE, and the DT culture degraded 34.3 +/- 2.97% of the TCE. The addition of methanol to cultures grown on methane reduced TCE degradation to 16.21 +/- 1.17% for OB3b and to 5.08 +/- 0.56% for JS. Although methanol reduces the toxicity of TCE to the cultures, biodegradation of TCE cannot be sustained in methanol-grown cultures. Since high TCE concentrations appear to inhibit methane uptake and growth, we suggest the primary toxicity of TCE is directed towards the methane monooxygenase.
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ABSTRACT: Numerous technologies are readily available for on‐site above‐ground treatment of ground water contaminated with TCE. Proper delineation of the extent of the contamination in the vadose and the saturated zones and bedrock remains the main problem responsible for the disappointing record of the full‐scale remediation efforts so far. A comprehensive approach is advocated that combines the pump‐and‐treat technology and in situ remediation, with particular emphasis on biological processes, as the least cost alternative.
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ABSTRACT: To determine if compounds added during trichloroethylene (TCE) degradation could reduce the loss of enzyme activity or increase enzyme recovery, different compounds serving as energy and carbon sources, pH buffers, or free radical scavengers were tested. Formate and formic acid (reducing power and a carbon source), as well as ascorbic acid and citric acid (free radical scavengers) were added during TCE degradation at a concentration of 2 mM. A saturated solution of calcium carbonate was also tested to address pH concerns. In the presence of formate and methane, only calcium carbonate and formic acid had a beneficial effect on enzyme recovery. The calcium carbonate and formic acid both reduced the loss of enzyme activity and resulted in the highest levels of enzyme activity after recovery.Applied Biochemistry and Biotechnology 02/1997; 63-65(1):789-96. DOI:10.1007/BF02920475 · 1.74 Impact Factor
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