Airborne bacterial communities associated with particulate matter in Temuco (Chile), one of the most air-polluted cities in South America

Abstract

Temuco city is categorized as one of the most air-polluted cities in Latin America; consequently, an air quality monitoring (AQM) program based on low-volume air samplers has been established by the Chilean government. However, AQM program does not consider any microbiological parameters to be analyzed. In this context, we firstly investigated the bacterial communities contained in particulate matter fractions (PM₁₀ and PM_2.5) collected by AQM program in Temuco city. Secondly, we compared the bacterial communities collected by AQM program with those collected by an environmental monitoring (EM) sampling using a high-volume air sampler. The potential relation between bacterial abundances and some environmental parameters was also addressed. In AQM samples, significant differences of bacterial abundances between PM fractions were not revealed by qPCR, although DNA metabarcoding analysis showed significant differences in bacterial diversities between PM fractions. When both EM and AQM sampling methods were compared, significant differences in abundance and diversity were observed, but differences between PM factions in each method were not found. Independent of sampling method, a negative relation between bacterial abundances and relative humidity was observed. Similarly, Proteobacteria (Pseudomonadota), Bacteroidetes (Bacteroidota) and Actinobacteria (Actinomycetota) were the dominant phyla observed in both methods by DNA metabarcoding analysis. Here, we demonstrated that the AQM program may be used as a source of samples for airborne bacteria studies; however, in case microbiological parameters will be incorporated or adopted in the AQM program, those data should be complemented with other sampling methods.