DIVERSITY OF AEROMONAS SP IN FLEMISH DRINKING-WATER PRODUCTION PLANTSAS DETERMINED BY GAS-LIQUID-CHROMATOGRAPHIC ANALYSIS OF CELLULAR FATTY-ACID METHYL-ESTERS (FAMES)

Gas-liquid chromatography of cellular fatty acid methyl esters (FAMEs) was used to determine the phenotypic and genotypic diversity among 48 9 presumptive Aeromonas strains isolated from five Flemish drinking wa ter production plants. FAME profiles were compared with the predetermi ned library profiles of a representative database, AER48C, which conta ins the mean FAME data of al 14 currently established hybridization gr oups (HGs) or genospecies within Aeromonas. Using AER48C, more than 93 % (457 strains) of all presumptive aeromonads isolated on ampicillin-d extrin agar were unequivocally identified as belonging to this genus. Moreover, 85.5% and 73.5% of these strains could be assigned to a part icular phenospecies or HG, respectively. Raw and treated surface water samples were dominated by members of the Aer. hydrophila complex (38. 8%, comprising HGs 1-3), followed by the Aer. caviae complex (22.7%, c omprising HGs 4-6) and the Aer. sobria complex (16.7%, comprising HGs 7-9). HGs 3, 5A/B and 8 were the most prominent genospecies in this ty pe of water. On the other hand, it was found that raw and treated phre atic groundwater samples displayed a much more limited species diversi ty since these were almost entirely dominated (95.8%) by strains belon ging to HGs 2 and 3 of the Aer. hydrophila complex. In general, floccu lation-decantation and sand filtration were not shown to influence the overall species distribution in any of the plants examined.