Analyses of culturable microorganisms and chemical pollutants in the air of urban and rural areas in the region of São Paulo, Brazil

Abstract

Bioaerosols are particles of great importance for several fields of research, and spores produced by fungi can exist as bioaerosols when suspended in the air. Microbiological standards for environmental monitoring of outdoor air parameters can be achieved by analyzing the relationship between airborne microorganisms and the prevailing environmental conditions. The outdoor air of the Metropolitan Region of São Paulo and the rural area in a city of the state of São Paulo (Ibiúna/SP), both in Brazil, were evaluated for the presence of microorganisms using the MAS-100 ECO (Merck®, Fr.) and M Air T (Millipore®) air sample collectors. Dichloran Rose-Bengal Chloramphenicol and Tryptic Soy Agars were used for fungal and bacterial isolation, respectively. Bacterial colonies were counted, and the plates with fungal colonies were sent for phenotypic identification up to genus and species level, respectively. Data on pollutant concentrations were obtained from the Environmental Company of the State of São Paulo. The highest number of Colony-Forming Units/m³ (CFU/m³) of microorganisms was measured in the winter and summer seasons, respectively, but the greatest Spore-Forming Units (SFU) of fungi were found in the rural area, where pollutant concentrations were lower. Nitrogen dioxide (NO₂) had a slightly positive influence on the concentration of SFU of fungi in both areas studied. Sulfur dioxide (SO₂) pollutant concentrations had both positive and negative great relations showing influence on microbial counts in the air of the rural area. In the rural area, the low bacteria count was influenced negatively by the low concentration of carbon monoxide (CO). The microbial counts were related to each other, as well as to the concentrations of pollutants, shown by all the correlations seen, indicating microorganisms as biomarkers of pollution in outdoor areas. The influence of environmental factors on the population and outdoor air biome is also explicit.