Sensitivity of a Phototrophic Bacterium to the Herbicide Sulfometuron Methyl, an Inhibitor of Branched Chain Amino Acid Biosynthesis

Sulfonyl urea-herbicides (sulfometuron methyl, chlorsulfuron) strongly inhibit phototrophic growth of the bacterium Rhodospirillum rubrum in the absence of ʟ-valine as a feedback inhibitor of the enzyme acetohydroxy acid synthase. The latter enzyme was shown to be highly sensitive to the sulfonyl urea and, to a much lesser extent, to an imidazolinone herbicide (Arsenal®).