The effects of benzoate, cyclohex-1-ene carboxylate, and cyclohexane carboxylate on biotransformation of o-phthalate in sediment slurries under sulfate-reducing conditions

It was found in this study that while addition of the predicted intermediate product benzoate did not, addition of cyclohex-1-ene or cyclohexane carboxylate did inhibit the biotransformation of o-phthalate in sulfate-reducing o-phthalate-adapted sediment slurries under a CO2/H2 atmosphere. Biotransformation rates of benzoate were slightly higher than those of o-phthalate in sediment slurries amended with o-phthalate plus benzoate.By using the most probable number (MPN) method to determine the number of o-phthalate transformers, similar growth dynamics of o-phthalate transformers were observed in sediment slurries amended with or without benzoate. The number of benzoate transformers (1 × 109 cells g−1 of sediment) remained the same in sediment slurries repeatedly amended with a mixture of o-phthalate and benzoate after their transformation. o-Phthalate transformers decreased about three orders (1 × 109 to 1 × 106 cells g−1 of sediment) of magnitude after biotransformation of o-phthalate, and remained at the low number thereafter until re-amendment with o-phthalate. o-Phthalate transformers increased to 1 × 108 cells g−1 of sediment just prior to the onset of biotransformation of the o-phthalate.