Analysis at the genomospecies level of microbial populations changes in activated sludge: The case of Aeromonas

To study how microbial populations in activated sludge change over rime, an analysis of Aeromonas populations From a municipal activated sludge plant was carried out at two different periods: the first was characterized by lo w influent biochemical oxygen demand (BOD), chemical oxygen demand (COD), N H4+ and PO43-, and the other by high values. Aeromonas strains were isolate d on 10 mu g/l of C-glucose in starch glutamate ampicillin penicillin (SGAP -10C) medium and classified into 12 DNA hybridization groups (DHG), using b iochemical tests and numerical identification. Strains not differentiated b y this method were ribotyped. Results revealed a difference in composition of Aeromonas DHGs: in the period characterized by high values of the parame ters measured, the activated sludge displayed a wide diversity, whereas the period with low values showed reduced diversity and a modification df the dominant DHGs. (C) 2000 Elsevier Science Ltd. All rights reserved.