Methanogenic Degradation of Anthranilate (2-Aminobenzoate)

Methanogenic enrichment cultures were obtained from anoxic sediments and sewage sludge with anthranilate (2-aminobenzoate) as sole source of carbon and energy. Gram-negative short rods predominated in these cultures and, together with hydrogen-utilizing methanogens, fermented anthranilate to acetate, CO 2, methane and ammonia. These enrichment cultures degraded also benzoate without a lag. In cultures inhibited with bromoethanesulfonate, benzoate accumulated in stoichiometric amounts. These findings indicated (1) that anthranilate degradation depended on a syntrophic cooperation of fermenting bacteria and hydrogen-oxidizing methanogens, and (2) that anthranilate was first deaminated to benzoate before ring cleavage.