We have extracted DNA from bioreactors and aerosol samples to study the microbial composition and the functional genes of the sampled community. PCR-based sequencing was used for rapid microbial community analysis while shotgun metagenomics sequencing was used to characterize the microbial and functional composition of the sampled community. For e.g. in aerosol samples, we studied the microbial composition changes in between the non-event day (good PM2.5 condition) and event day (bad PM2.5 condition). Also, by using the bioinformatics approach, we can identify the functional genes presents in the sampled community.