Study of bioaerosols and site influence in the La Plata area (Argentina) using conventional and DNA (fingerprint) based methods

The present study approaches the characterization of seasonal samples of bioaerosols taken during 2005-2006 in rural, urban, industrial, coastal and residential sites within La Plata area, Buenos Aires, Argentina. Culturable airborne fungal and bacterial communities were collected on DG18 agar and R2 Agar plates respectively, using a single-stage SKC sampling device. Fungal genera were identified based on their micro- and macro-morphological characteristics. Bacterial populations were analyzed by denaturing gradient gel electrophoresis (DGGE) of PCR 16SrDNA bacterial amplification. Geometric mean concentration of bacteria and fungi ranged from 10 to 10³ CFU m-³ and were comparable with those from other reports. No differences were observed among sites for fungi and Cladosporium sp. was predominant, with 85.7% of total concentration counts; secondary genera that contributed were Alternaria (6.7%), Penicillium (1.8%), Aspergillus (1.3%), Epicoccum (1.0%) and the group of yeasts (1.9%). The dominance of Cladosporium in all sites suggests that the most abundant fungal aerosol was neither significantly affected nor primarily generated by any anthropogenic area source more than the natural ambience present in the La Plata area. With regard to bacteria, the results showed on several occasions differences in concentration among sites during sampling events, but these differences were not observed when the community structure was analyzed by means of DGGE. Bacterial DGGE banding profiles from all sites revealed the existence of a relatively diversified, culture-based airborne community. Construction of similarity dendrograms exposed a distribution of site samples in which replicates intra-site equalled those encountered among sites, rendering substantial inference of site distinction unfeasible.