New DNA sequences from bacteria converting phenol into acetate under strict anaerobic conditions

This work reports new fragments of DNA sequences related to microbes able to degrade phenol into acetate under strict anaerobic conditions. For this purpose, anaerobic digesting sludge was acclimatised to degrade phenol, then heat treated and in turn used as fermentative sludge. The resulting microbial community was able to convert phenol into acetate under anaerobic conditions (kinetic constants: 0.396 ± 0.01 and 0.345 ± 0.04 mg of compound L-1 day-1, respectively). Microscopic, chemical and molecular analyses revealed that only bacteria were present in the final sludge and thus methanogens were eliminated. The bacteria were mainly Gram-negative sporeforming rods, belonging to the Deltaproteobacteria class and had a tendency for aggregation. These are also phenotypically related to organisms thriving at extreme environments. Cloning, temperature gradient gel electrophoresis (TGGE) and probe matching of a short 16S DNA fragment revealed that these new microbes are evolutionary related to, and share 90% of similarities with, Desulfovibrio sp.