Three-Year Monitoring of Microorganisms' Composition and Concentration in Atmospheric Aerosols of Novosibirsk City and Suburbs

Abstract

The atmospheric environment is formed under the influence of local and distant sources as a result of horizontal and vertical transport. In the present work, microbiological analysis of 604 samples of atmospheric aerosol collected in the period from September 2020 to September 2023 at four sites differing in anthropogenic load, located in Novosibirsk and the region, was carried out. Day and night aerosol samples were collected during 12 h every two weeks by filtration using Sartorius reinforced Teflon membranes, then sown on a set of nutrient media. The taxonomic affiliation of the isolated microbial isolates was determined based on phenotypic characteristics and analysis of 16S rRNA gene nucleotide sequences. Changes in the composition and concentration of culturable microorganisms depending on the season, time of day, and site of aerosol sampling were observed. In winter, lower fungi and bacteria of the genera Bacillus, Staphylococcus, Micrococcus dominated with an average concentration from zero to 12.5 CFU/m³ of aerosol. In the warm period, the concentration and diversity of cocci, spore-forming and non-spore-forming bacteria, actinomycetes, and fungi (up to 1970 CFU/m³), among which pathogenic microorganisms were found, increased sharply in aerosols. The use of 16S metabarcoding techniques has greatly expanded the range of aerosols' microbial diversity detectable.

Keywords: 16S rRNA; Novosibirsk; atmospheric aerosol; biodiversity; concentration; metabarcoding; microorganisms; pathogenicity.

Figure 1

Sampling sites of atmospheric aerosols in Novosibirsk and the region. Explanations are in the text.

Figure 2

(A)—quantitative ratio of different groups of microorganisms from the total number of isolated microorganisms (%); (B)—concentration (CFU/m³) of culturable microorganisms of different groups in samples of atmospheric aerosols of Novosibirsk and the region in 2020. “nonspore”—non-spore-bearing bacteria; “act”—actinomyces. Aerosol sampling sites: A—Akademgorodok (Sovetsky district of Novosibirsk); C—Novosibirsk (Kalininsky district); N—settlement Dvurechye, Novosibirsk suburbs; V—settlement Koltsovo, Novosibirsk suburbs (Figure 1).

Figure 3

Daily dynamics of the concentration of culturable microorganisms in the studied atmospheric aerosols (CFU/m³). Aerosol sampling sites: A—Akademgorodok (Sovetsky district of Novosibirsk); C—Novosibirsk (Kalininsky district); N—settlement Dvurechye, Novosibirsk suburbs; V —settlement Koltsovo, Novosibirsk suburbs (Figure 1).

Figure 4

Concentration and composition of culturable microorganisms isolated from atmospheric aerosol samples from Novosibirsk and the region in 2021–2023. Aerosol sampling site designations are the same as in Figure 3.

Figure 5

Relative abundance (%) of genera-specific 16S rRNA gene amplicon sequences in the aerosol samples. For samples 205, 206, w1–w3 metabarcoding was used, but Km and Sb were analyzed by Sanger sequencing.

Figure 6

The principal component analysis of samples at the genus level. Principal component 1 and 2 explained 75.0% and 17.3% of the total variations, respectively. Red names of top seven taxa by the longest loading vector length are indicated.

Figure 7

Venn diagram of genera intersection for samples analyzed by 16S metabarcoding (DNA from filters (205, 206) and tiny colonies (w1, w2, w3)) and full 16S Sanger sequencing of isolates (Km and Sb).