As a result of these problems, Speitel says that biodegradation has emerged as the most promising treatment method. Biodegradation offers attractive economics, the potential for complete destruction of chemicals and the ability to treat chemicals at the site of contamination. Past biodegradation research with TCE has resulted in low biodegradation rates which indicate that its commercial viability as a treatment process may be questionable. TCE biodegradation rates for this particular methylotroph are 100 to 1000 times greater than those observed with other organisms. The first step in the aerobic oxidation of methane to carbon dioxide by methylotrophs is the oxidation of methane to methanol.
Solvents are among the chemicals oxidized.
Expression of the MMO enzyme in many methylotrophs, including Methylosinus trichosporium OB3b, is not completely understood. It can be present in a soluble or particulate form, but the large TCE biodegradation rates observed with Methylosinus trichosporium OB3b only occur when soluble MMO is the dominant form of the enzyme. This organism's high biodegradation rate occurs only under specific environmental conditions - which are presently not established. These unknown ideal parameters and the organism Methylosinus trichosporium are the focus of Speitel and Georgiou's current research. Speitel says that the challenge is to develop a viable treatment process to stimulate soluble MMO production and maintain this production over the long term under treatment conditions typically encountered in practice.