ROLE OF THE INTRACELLULAR NAD(P)H LEVEL AND THE ACTIVITY OF THE RESPIRATORY-CHAIN AT THE INITIAL-STAGE OF THE BACTERIAL TRANSFORMATION OF OXADIAZONE

The role of the intracellular NAD(P)H level and the activity of the re spiratory chain at the initial stage of the bacterial transformation o f the persistent herbicide oxadiazone was investigated. During the inc ubation of Agrobacterium tumefaciens with oxadiazone in a phosphate bu ffer, the concentration of the herbicide decreased from 900 to 200 mg/ l in the first two days and then increased to 450 mg/l. The rate of ox adiazone transformation increased with the rate of microbial respirati on, but was not correlated with the intracellular level of NAD(P)H, wh ich varied from 30 to 350 mu M. Based on in vivo and in vitro experime nts, it can be inferred that oxadiazone is initially reduced by A. tum efaciens; the reduced form is then transformed into tyl-2-(2,4-dichlor o-5-isopropoxyphenyl)-hydrazine. The electrons for oxadiazone reductio n are donated by one of the components of the bacterial respiratory ch ain.