Inhibition of aerobic respiration and dissimilatory perchlorate reduction using cyanide

Abstract

The effect of low concentrations of cyanide on dissimilatory perchlorate and chlorate reduction and aerobic respiration was examined using pure cultures of Azospira sp. KJ. Cyanide at a concentration of 38 microM inhibited cell growth on perchlorate, chlorate and molecular oxygen, but it did not inhibit the activity of chlorite dismutase. When oxygen accumulation was prevented by adding an oxygen scavenger (Oxyrase or L-cysteine), however, cells completely reduced perchlorate in the presence of cyanide. It was concluded that the inhibition of dissimilative perchlorate reduction by cyanide at this concentration was a consequence of oxygen accumulation, not inhibition of the enzymes used for perchlorate reduction. This finding on the effect of cyanide on respiratory enzymes provides a new method to control and study respiratory enzymes used for perchlorate reduction.

Expression of Chlorite Dismutase and Chlorate Reductase in the Presence of Oxygen and/or Chlorate as the Terminal Electron Acceptor in Ideonella dechloratans

“…The oxygen produced by the action of chlorite dismutase during (per)chlorate respiration is believed to be used by a terminal oxidase in the (per)chlorate-respiring bacteria concomitant with (per)chlorate respiration (1, 24). However, oxygen at higher concentrations is known to inhibit (per)chlorate reduction (12,24,27,34,39). For some species, inhibition can be observed immediately upon introduction of oxygen to anaerobically grown cultures (12,34).…”

“…A concentration of dissolved oxygen as low as 1.6 M has been reported to inhibit growth of Azospira sp. strain KJ (27). The ability to perform (per)chlorate reduction is restored when (per)chlorate is offered as the sole electron acceptor, but recovery phases extending from hours to several days have been observed (26,39,44).…”