The growth and activity of microbes has been heavily studied in nearly every environment on Earth, but there have been limited studies focusing on the air. In the air, microbes are present at 104-105 cells/m3 air and the air contains various compounds that could serve as simple microbial growth substrates at sufficient concentrations. Previous laboratory studies have demonstrated that airborne Serratia marcescens was able to grow in water droplets. However, most of the atmosphere does not contain water droplets. When not associated with water droplets, airborne Sphingomonas aerolata NW12 synthesized more ribosomes when provided a carbon substrate and synthesized new proteins. This activity suggests the potential for microbes to grow in the air outside of water droplets on volatile compounds such as CH4. To examine airborne microbial communities, we aerosolized cultures into 320 L rotating gas-phase bioreactors and assessed the half-lives and distributions of the particles. We investigated the ability of airborne methanotrophs to grow on CH4 using DNA-stable isotope probing (DNA-SIP). The cultures were aerosolized into the gas-phase reactors and amended with 1500 ppmv 13CH4 or 12CH4. The cells were suspended in air for five days, harvested, and analyzed for 13C incorporation into DNA by gradient fractionation/qPCR methods. Some results demonstrated 13C incorporation into DNA, indicating growth in air, and other experimental replicates did not. We conclude that methanotrophs outside of water droplets in the air can potentially grow under certain conditions. Based on our data, low biomass is the main limitation for utilizing the DNA-SIP method for detecting activity of airborne methanotrophs. Current work is investigating this and other limitations, as well as further exploring the potential activity of airborne microbes.

Determining the growth capability of airborne methanotrophs

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.