Affiliation:
1. Department of Chemical Engineering and Department of Civil Engineering, 2 University of Texas, Austin, Texas 78712
Abstract
The methanotrophic bacterium
Methylosinus trichosporium
OB3b is unusually active in degrading recalcitrant haloalkanes such as trichloroethylene (TCE). The first and rate-limiting step in the degradation of TCE is catalyzed by a soluble methane monooxygenase (sMMO). This enzyme is not expressed when the cells are grown in the presence of copper at concentrations typically found in polluted groundwater. Under these conditions,
M. trichosporium
OB3b expresses a particulate form of the enzyme (pMMO), which has a narrow substrate specificity and does not degrade TCE at any significant rate. We have isolated
M. trichosporium
OB3b mutants that are deficient in pMMO and express sMMO constitutively in the presence of elevated concentrations of copper. One mutant (PP358) exhibited a TCE degradation rate which was almost twice as high as that of the wild-type strain grown under optimal conditions (without copper). All of the mutants lost the ability to express pMMO activity and to form stacked intracellular membranes characteristic of wild-type cells expressing pMMO.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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