Inhibition of diethyl ether degradation in Rhodococcus sp. strain DEE5151 by glutaraldehyde and ethyl vinyl ether

Abstract

Alkyl ether-degrading Rhodococcus sp. strain DEE5151, isolated from activated sewage sludge, has an activity for the oxidation of a variety of alkyl ethers, aralkyl ethers and dibenzyl ether. The whole cell activity for diethyl ether oxidation was effectively inhibited by 2,3-dihydrofurane, ethyl vinyl ether and glutaraldehyde. Glutaraldehyde of less than 30 microM inhibited the activity by a competitive manner with the inhibition constant, K(I) of 7.07+/-1.36 microM. The inhibition type became mixed at higher glutaraldehyde concentrations >30 microM, probably due to the inactivation of the cell activity by the Schiff-base formation. Structurally analogous ethyl vinyl ether inhibited the diethyl ether oxidation activity in a mixed manner with decreasing the apparent maximum oxidation rate, v(max)(app), and increasing the apparent Michaelis-Menten constant, K(M)(app). The mixed type inhibition by ethyl vinyl ether seemed to be introduced not only by the structure similarity with diethyl ether, but also by the reactivity of the vinyl ether with cellular components in the whole cell system.

Physiological, numerical and molecular characterization of alkyl ether‐utilizing rhodococci

“…The PrmA/ThmA‐like protein group appears to take part in the monooxygenation and hydroxylation of gaseous and volatile alkanes, aryl alkyl hydrocarbons and cyclic AEs at an internal carbon position with a relatively low electron density. A similar action has been proposed for linear AE degradation by AE‐utilizing strain DEE5151, the activity of which is inhibited by ethyl vinyl ether and glutaraldehyde (Kim and Engesser, 2004; 2005). A fortuitous loss of the activity indicates involvement of only one enzyme system in the degradation of a broad range of linear AEs from diethyl ether to di‐ n ‐heptyl ether, aryl AEs and dibenzyl ether, even though the exact mechanism of AE degradation and the routes of activity loss are yet to be determined from knowledge of the putative dee genes.…”