Biomonitoring of continuous microbial community adaptation towards more efficient phenol-degradation in a fed-batch bioreactor

The anaerobic degradation of phenol was studied in a fed-batch culture. Nit rate was added as electron acceptor and phenol was provided three times, to a final concentration of 200 mg/l. Randomly amplified polymorphic DNA (RAP D) and terminal fraction fragment length polymorphism (T-RFLP) were used an d compared in order to monitor the microbial succession in the reactor. Phe nol degradation started after an initial lag phase of 14 days and was then completed within a few days. In addition. the duration of the lag phase was shortened and the degradation rate was increased after each phenol amendme nt. Nitrate reduction correlated with microbial growth and phenol depletion , confirming that the degradation was carried out anaerobically. Results fr om the DNA analysis showed that the structure of the microbial community ch anged after each phenol amendment. This study confirms the potential for an aerobic degradation of environmental pollutants and also confirms that micr obial acclimation towards faster degradation rates occurred upon repeated s ubstrate amendments. Furthermore. both of the DNA-based techniques describe d the phenol degradation-linked community shifts with similar general resul ts. RAPD is a faster, simpler technique that gives a higher resolution and consequently reflects the shifts in the microbial community structure bette r. whereas T-RFLP is more suitable for phylogenetic studies.