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Phenol degradation by Acinetobacter calcoaceticus NCIB 8250
G Paller1, R K Hommel, H P Kleber
1Institut für Biochemie, Fakultät für Biowissenschaften, Pharmazie und Psychologie, Universität Leipzig, Germany.
Journal of Basic Microbiology
|January 1, 1995
Summary
Acinetobacter calcoaceticus efficiently degrades phenol using an ortho-cleavage pathway. Ethanol represses phenol utilization, but fed-batch cultivation enhances tolerance and degradation rates.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Acinetobacter calcoaceticus NCIB 8250 metabolizes phenol as a sole carbon and energy source.
- Phenol degradation occurs via an ortho-cleavage pathway.
- Ethanol presence inhibits phenol utilization in mixed substrates.
Purpose of the Study:
- Investigate phenol degradation by Acinetobacter calcoaceticus.
- Characterize the enzyme responsible for phenol hydroxylation.
- Determine factors affecting phenol tolerance and degradation rates.
Main Methods:
- Fed-batch cultivation to assess phenol tolerance.
- Spectrophotometric enzyme assays to characterize phenol hydroxylase.
- Enzyme kinetic studies to determine kinetic parameters (Km, pH, temperature optima).
Main Results:
- Fed-batch cultivation increased phenol tolerance twofold, with maximum degradation rates of 150 mg phenol/h.
- Phenol hydroxylase and catechol-1,2-dioxygenase are induced by phenol.
- Partially purified phenol hydroxylase has apparent Km values of 147 µM (phenol), 35 µM (FAD), and 416 µM (NADPH).
- The enzyme exhibits broad substrate specificity, hydroxylating cresols and chlorophenols, with higher rates for pyrogallol and resorcinol.
Conclusions:
- Acinetobacter calcoaceticus effectively degrades phenol via an ortho-cleavage pathway.
- Phenol hydroxylase activity is crucial for phenol degradation and is influenced by FAD and NADPH.
- The bacterium demonstrates enhanced phenol tolerance and degradation capabilities under specific cultivation conditions.