Identifying the sources of biosolid derived pathogen indicator organisms in aerosols by ribosomal DNA fingerprinting

The application of the ribosomal DNA (rDNA) fingerprinting method to identi fy the sources of aerosolized clostridia isolates at a commercial biosolid land application site is being reported. Clostridia isolates were initially isolated from aerosol samples as well as from biosolid piles on the ground . Oligonucleotide primers, specific to the bacterial 16S-23S interspacer re gion were employed in gene amplification reactions to amplify the region. F or those isolates that generated similar sized amplification products, the products were digested with the HindIII restriction endonuclease to determi ne genetic differences. Using this approach, it was possible to genetically link some of the aerosol isolates to the biosolid piles. The results sugge st that for tracking the sources of aerosolized clostridia, it would be nec essary to amplify the 16S-23S region, and if necessary, followed by restric tion enzyme analyses of the product. The region, and if necessary, followed by restriction enzyme analyses of the product. The need for restriction en zyme analyses would be necessary only if the isolates in question had ampli fication products of similar sizes.