IDENTIFICATION OF ANAEROBIC DIGESTER BACTERIA USING A POLYMERASE CHAIN-REACTION METHOD

The possibility of identifying the bacteria in a sewage-sludge anaerob ic digester by using the polymerase chain reaction to amplify 16S rRNA sequences from digester contents and comparing these with a general d atabase of sequences was investigated. The database comprised bacteria from many ecosystems but not from digesters. No digester sequences we re completely identical with those in the database. However, the datab ase sequences most closely corresponding were representatives of gener a, or in some cases species, of bacteria which had been previously cul tured from digesters, or might have been present in the feedstock of t he experimental digester. Digester floras are known to be heterogeneou s and it is suggested that it is more likely that the sequences were f rom strains of digester bacteria related to, but not exactly the same as, bacteria in the database rather than being from entirely unknown b acteria. While exact identification would depend on comparisons with d ata from digester isolates, comparisons with a general database might be used to tentatively identify bacteria homologous to those in digest ers and possibly to follow changes with time in a digester flora.