Bioremediation is one of the most effective ways to treat and dispose of chlorinated hydrocarbons, and methanotrophs are potentially useful to do so. Recent studies found that facultative methanotrophs can use compounds containing C-C bond as sources of carbon and energy, thus overcoming the limitation that obligate methanotrophsone uses only C1 compounds for this process. This is a unique metabolic approach that is becoming increasingly attractive in the field of contaminant biodegradation. Here, we summarized the bioremediation of chlorinated hydrocarbons by obligate and facultative methanotrophs. This process involves the degradation of various chlorinated hydrocarbons by diverse strains, including pure cultures and mixed cultures. We also compare the activity expression and catalytic properties of different types of methane monooxygenases in various substrates. We furthermore summarize the kinetic characteristics of the degradation of chlorinated hydrocarbons using the model strain Methylosinus trichosporium OB3b, and outline the degradation and potential of chlorinated hydrocarbons by facultative methanotrophs. Lastly, we discuss current problems and future research directions for degradation of chlorinated hydrocarbons by methanotrophs.
Biodegradation, Environmental ; Hydrocarbons, Chlorinated ; metabolism ; Methylosinus trichosporium ; metabolism ; Oxygenases ; metabolism

Methanotrophs can catalyze hydroxylate of methane and some hydrocarbon. Which play an important role in mitigating global warming and have also potential significance for industrial applications or bioremediation. A high activity of hydroxylase, a crucial component in sMMO, from Methylosinus trichosporium IMV 3011 has been purified to homologues by using chromatographic techniques. The molecular weight of the hydroxylase determined by gel filtration is 201.3 kD, and SDS-PAGE showed that hydroxylase consists of three subunits(alpha beta gamma) with molecular weights of 58kD, 36kD and 23kD respectively, drawing a comparison both methods indicated that the hydroxylase is a homodimer with an (alpha beta gamma)2 configuration. Purified hydroxylase has a pI at 5.2 judged by thin layer isoelectric focusing. The purified hydroxylase contains 3.02 mol of iron per mol of protein. The stability pH for the hydroxylase in solution is 5.8-8.0 and the stability temperature is below 35 degrees C. The cells form show a long, bent, and rod-shaped with even surface observed by scanning electron microscopy.
Chemical Phenomena ; Enzyme Stability ; Hydrogen-Ion Concentration ; Iron ; metabolism ; Methylosinus trichosporium ; enzymology ; Microscopy, Electron ; Oxygenases ; chemistry ; isolation & purification ; metabolism ; Spectrometry, Fluorescence ; Spectrophotometry, Ultraviolet ; Temperature

Using a fluidized bed as immobilization system, mixed culture methanotrophic attached-films were developed on diatomite particles. The Methane Monooxygenase (MMO) activity was found to increase obviously as soon as the lag phase ended. Greater than 90% of the MMO activity in the bed was attached. Biofilm concentration of 3.3-3.7 mg dry weight cell/g DS was observed. Batch experiments were performed to explore the possibility of producing epoxypropane by a cooxidation process. The effect of methane on the oxidation of propene to epoxypropane and the effect of propene on the growth of methanotroph were also studied. In continuous experiments, optimum mixed gaseous substrates (methane: 35%; propene: 20%; oxygen: 45%) were continuously circulated through the fluidized bed reactor to remove product. Initial epoxypropane productivity was 110-150 mumol/d. The bioreactor operated continuously for 25 d without obvious loss of epoxypropane productivity.
Adhesins, Bacterial ; physiology ; Biofilms ; growth & development ; Bioreactors ; microbiology ; Cells, Immobilized ; drug effects ; enzymology ; microbiology ; Epoxy Compounds ; metabolism ; Methane ; metabolism ; pharmacology ; Methylococcaceae ; drug effects ; enzymology ; growth & development ; Methylosinus ; drug effects ; enzymology ; growth & development ; Oxidation-Reduction ; Oxygenases ; metabolism ; Propane ; metabolism ; pharmacology