Oxidation of Methyl tert -Butyl Ether by Alkane Hydroxylase in Dicyclopropylketone-Induced and n -Octane-Grown Pseudomonas putida GPo1

Abstract

The alkane hydroxylase enzyme system in Pseudomonas putida GPo1 has previously been reported to be unreactive toward the gasoline oxygenate methyl tert-butyl ether (MTBE). We have reexamined this finding by using cells of strain GPo1 grown in rich medium containing dicyclopropylketone (DCPK), a potent gratuitous inducer of alkane hydroxylase activity. Cells grown with DCPK oxidized MTBE and generated stoichiometric quantities of tert-butyl alcohol (TBA). Cells grown in the presence of DCPK also oxidized tert-amyl methyl ether but did not appear to oxidize either TBA, ethyl tert-butyl ether, or tert-amyl alcohol. Evidence linking MTBE oxidation to alkane hydroxylase activity was obtained through several approaches. First, no TBA production from MTBE was observed with cells of strain GPo1 grown on rich medium without DCPK. Second, no TBA production from MTBE was observed in DCPK-treated cells of P. putida GPo12, a strain that lacks the alkane-hydroxylase-encoding OCT plasmid. Third, all n-alkanes that support the growth of strain GPo1 inhibited MTBE oxidation by DCPK-treated cells. Fourth, two non-growth-supporting n-alkanes (propane and n-butane) inhibited MTBE oxidation in a saturable, concentration-dependent process. Fifth, 1,7-octadiyne, a putative mechanism-based inactivator of alkane hydroxylase, fully inhibited TBA production from MTBE. Sixth, MTBE-oxidizing activity was also observed in n-octane-grown cells. Kinetic studies with strain GPo1 grown on n-octane or rich medium with DCPK suggest that MTBE-oxidizing activity may have previously gone undetected in n-octane-grown cells because of the unusually high K s value (20 to 40 mM) for MTBE.

Activity-Based Protein Profiling of Ammonia Monooxygenase in Nitrosomonas europaea

“…ELW1 (43). The well-studied alkane hydroxylase in Pseudomonas oleovorans GPo1 is also irreversibly inactivated by 17OD (44)(45)(46).…”

Genes involved in the methyl tert-butyl ether (MTBE) metabolic pathway of Mycobacterium austroafricanum IFP 2012

“…The hypothesis that the monooxygenase responsible for MTBE and TBA oxidation might be located in the membrane deserves further investigation, since we did not analyse this cell compartment. In this regard, the membrane-bound alkane hydroxylase could be a candidate, since several bacterial strains are able to degrade MTBE by cometabolism after growth on alkanes (Garnier et al, 1999;Smith & Hyman, 2004;Smith et al, 2003).…”

Isolation and characterization of naphthalene biodegrading Methylobacterium radiotolerans bacterium from the eastern coastline of the Kingdom of Saudi Arabia

“…For instance, P. aeruginosa can grow in the presence of a variety of aliphatic and aromatic compounds such as lactate (Gao et aromatic fl uoranthene, phenanthrene (Zhang et al 2011), hexadecane, benzene, toluene (S Mukherjee et al 2010), paracetamol (Hu et al 2013), and 4-chlorobenzoate (Hoskeri et al 2011). Similar wide range of assimilation of substrates has been reported with other species of the same genus, such as Pseudomanas putida with biodegradation of aromatic compounds (Diaz et al 2008, Ebrahimi and Plettner 2013, El-Naas et al 2009, Fernandez et al 2012, Hwang et al 2009, Li et al 2011, Q Lin and Jianlong 2010, Phale et al 2013, Takeo et al 2006, You et al 2013) and alkane derivatives (Dunn et al 2005, Johnson and Hyman 2006, Smith and Hyman 2004. In line with previous reports, Pseudomonas aeruginosa strain N7B1 had a wide range of substrate specifi city, thus is an important bacterium that could be used in bioremediation strategies.…”