Roles of tert-butyl formate, tert-butyl alcohol and acetone in the regulation of methyl tert-butyl ether degradation by Mycobacterium austroafricanum IFP 2012

• Published in: Applied microbiology and biotechnology Vol. 62; no. 2-3; pp. 256 - 262
• Main Authors: François, A, Garnier, L, Mathis, H, Fayolle, F, Monot, F
• Format: Journal Article
• Language: English
• Published: Germany Springer 01.08.2003; Springer Nature B.V
• Subjects: Acetone; Analysis; Biodegradation; Biodegradation, Environmental - drug effects; Cytochrome P-450 Enzyme System - metabolism; Degradation; Energy sources; Formates - pharmacology; Hydrogen-Ion Concentration; Kinetics; Metabolic regulation; Metabolites; Methyl Ethers - metabolism; methyl tert-butyl ether; Mixed Function Oxygenases - metabolism; Models, Biological; Molecular microbiology; MTBE; Mycobacteria; Mycobacterium; Mycobacterium - drug effects; Mycobacterium - growth & development; Mycobacterium - metabolism; Mycobacterium austroafricanum; Sulfuric acid; t-Butyl formate; tert-butyl alcohol; tert-Butyl Alcohol - pharmacology; tert-Butyl formate; France
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-003-1268-9

Mycobacterium austroafricanum IFP 2012 is a Gram-positive strain able to grow on methyl tert-butyl ether (MTBE) as a sole carbon and energy source. The effect of two downstream metabolites of MTBE, tert-butyl formate (TBF) and tert-butyl alcohol (TBA) on MTBE degradation was investigated using resting cells. The addition of low concentrations of TBF decreased the MTBE degradation rate by about 30%. In contrast, the addition of TBA did not have a significant effect on MTBE degradation rate, even at high concentrations; and it was also shown that TBA degradation occurred only once MTBE was exhausted. At neutral pH, TBF hydrolysis involved mainly an esterase-type activity regulated by the presence of TBA. The TBF degradation rate was about four times lower than the MTBE degradation rate. Furthermore, acetone was identified as an intermediate during TBA degradation. An acetone mono-oxygenase activity, inhibited by methimazole but not by acetylene, was suggested. It was different from the MTBE/TBA mono-oxygenase and, thus, acetone did not appear to compete with MTBE and TBA for the same enzyme. These new results show that the metabolic regulation of the early steps of MTBE degradation by M. austroafricanum IFP 2012 is complex, involving inhibition and competition phenomena.