Assessment of Culturable Bacteria Associated With Fine Particulate Matter Collected in Antioquia Colombia- South America

Abstract

In recent years, air pollution in urban and rural environments has been increasing and is one of the factors of greatest public health concern. PM2.5 particulate matter is one of the main pollutants that deteriorate air quality. This particulate matter can carry bioaerosols as bacteria and fungi. Due to its size or aerodynamic diameter of less than 2.5 μm, it can be inhaled to the pulmonary alveoli, which is strongly associated with a rise in mortality and morbidity in exposed populations. In this research, the presence of bacteria associated with the PM2.5 fraction of particulate matter was evaluated in two urban areas (Urban-C and Urban-NW) and one rural area (Rural-N) from the Aburrá Valley (Antioquia, Colombia South America). In recent years, this region has been presenting high concentrations of PM2.5, exceeding several times the daily permissible limits (50 μg/m3) for this air pollutant. The isolation, characterization and identification of bacteria associated with PM2.5 was performed by culture-dependent techniques, molecular characterization by ribosomal intergenic spacer analysis (RISA) and 16S rDNA sequencing, respectively. The dominant phylogenetic affiliations of the bacteria were grouped into three phyla: Proteobacteria, Actinobacteria and Firmicutes. The phylum Firmicutes dominated in all sampling points with several genera such as Bacillus, Staphylococcus, Paenibacillus, Lysinibacillus, Exiguobacterium and Macrococcus. Some species of these genera have been linked to pathogenicity in plants, animals and humans. Additionally, a greater presence of possible pathogenic microorganisms in urban areas was estimated, probably influenced by the concentration of PM2.5 and environmental conditions. These results provide important information to understand the distribution and ecology of airborne bacteria and demonstrate that the atmosphere in Colombia (Aburrá Valley) harbors bacteria that are clearly an important, but understudied, component of air quality that needs to be better integrated to the public health perspective.