Anammox bacteria enrichment and study of microbial community dynamics by q-PCR and pyrosequencing
Résumé
This study investigates the effect of nitrite on the microbial community dynamics during the enrichment of sludge performing anaerobic ammonium oxidation (anammox). Six inoculums were sampled from different environments and enriched under controlled conditions during 4 months. Two different nitrite supply strategies were applied; i.e., (i) low initial concentration at 25 mg NO2--N/L and progressive increase to 150 mg NO2--N/L, and (ii) constant high concentration at 150 mg NO2--N/L. Inoculums only developed anammox activity when working at initial low nitrite concentration. The highest specific anammox activity obtained was 118 mg NH4+-N/g VS/d. No correlation was found between the time of macroscopic evidence of ammonium oxidation and final specific anammox activity. Biomass samples were taken monthly and abundances of both total and anammox bacteria were assessed using quantitative polymerase chain reaction (q-PCR). In addition, 16S rDNA targeted pyrosequencing was used to identify the anammox species enriched and characterize the evolution of the microbial communities during enrichments.