Vanderbilt mineral medium was used in all batch
experiments [23]. Glucose was used as co-substrate to
provide the electrons for the reductive cleavage of the
azo dyes, namely DB 38 and CR. Sodium thioglycollate
was used to maintain anaerobic conditions. Hundred
milligram per litre dyes (37 mg COD/l for DB 38 and 74
mg COD/l for CR) and 1000 mg/l glucose-COD were
added separately to the synthetic medium. Furthermore,
2000 mg/l NaHCO3 was added to the medium to
maintain a residual alkalinity of 400 mg/l after 5 and 9
days of the incubation period.