Associations between bacteriome and chemical pollutants in indoor dust from Czech households

Background Indoor dust contains both microbes and chemical pollutants, creating a complex exposure environment for occupants. While their individual effects on health are known, interactions between microbial communities and chemicals remain poorly understood. Investigating these interactions can help understand potential health risks associated with indoor dust. Methods Indoor dust samples were collected from 88 households (53 flats and 35 houses). Associations among type of household, bacteriome characteristics obtained by 16S rRNA amplicon sequencing and qPCR, and concentrations of 46 selected chemical pollutants: bisphenols, musks, organophosphate flame retardants (OPFRs), oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs), PAHs, polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and phthalate esters were analyzed. Results Compared to indoor dust from flats, samples from houses showed higher concentrations of PAHs and higher relative abundances of the genera Methylobacterium-Methylorubrum and Sphingomonas . The relative abundance of the genera Methylobacterium-Methylorubrum positively correlated with that of Sphingomonas , concentrations of oxy-PAHs, and PAHs. Relations between Sphingomonas -PBDEs as well as Lactococcus- PCBs were observed. Concentrations of musks and PCBs correlated with bacteriome α-diversity, and, along with window opening, house age, air-conditioning, temperature, garden access, and indoor smoking, explained 37% of bacteriome α-diversity variability. Conclusions The bacterial genera Methylobacterium-Methylorubrum and Sphingomonas , some strains of which previously showed ability to degrade organic compounds, were associated with higher concentrations of PAHs and their derivatives, and PBDEs in indoor dust. Such interactions between biological and chemical pollutants in indoor dust may alter the risks associated with indoor environment, particularly for sensitive populations. Our study reports associations at the level of genera, preventing us from drawing any definite conclusions on the direction of causality or health implications; hence, further mechanistic studies at lower taxonomic levels are needed to shed more light on this issue.