Spatial and temporal patterns of public transit aerobiomes.

Area of Science:

• Environmental microbiology
• Metagenomics
• Urban ecology

Background:

• Aerobiome diversity is extensive but species-level structure is poorly understood.
• Public transit microbiomes are of health interest, yet understudied using shotgun metagenomics.
• Previous studies focused on single cities, limiting comparative analysis of aerobiome structure.

Purpose of the Study:

• To investigate spatial and temporal patterns in public transit aerobiome species diversity.
• To analyze bacterial and fungal communities within urban transit systems globally.
• To compare aerobiome composition across different cities.

Main Methods:

• Shotgun metagenomic sequencing of air samples from six global cities over three years (2017-2019).
• Utilized improved classification databases and stringent parameters for data processing to achieve high species-level resolution.
• Collected parallel data on human and environmental factors within the transit systems.

Main Results:

• Microbial diversity varied significantly among cities, with city of origin being the primary driver.
• Bacteria dominated the aerobiome, with higher abundance in densely populated cities.
• Complex aerobiomes comprised hundreds to thousands of species; interannual variation had minor impact.

Conclusions:

• Cities exhibit distinct bacterial and fungal aerobiome "signatures," suggesting geographical influence.
• No ubiquitous global species core was found, but city-specific "cores" were identified.
• Robust bioinformatics pipelines are crucial for analyzing low-biomass environmental samples.