Development of Stable Isotope Probing to Monitor Activity of Airborne Bacteria
Abstract
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 (Lighthart 2000) and the air contains various compounds that could serve as simple microbial growth substrates. Laboratory studies have demonstrated that airborne Serratia marcescens was able to grow in water droplets (Dimmick et al. 1979). 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 (Krumins et al. 2014) and synthesized new proteins (Krumins et al. in prep). This activity suggests the potential for microbes to grow in the air outside of water droplets. We investigated the ability of airborne microbes to grow on specific carbon substrates found in the atmosphere using DNA-stable isotope probing (DNA-SIP). Cultures were aerosolized into 320 L rotating gas-phase bioreactors and amended with either 13C-labelled acetic acid, carbon dioxide, or methane to examine the growth of different microbial guilds in the airborne state. The cells were suspended in air for a few days, harvested, and analyzed for 13C incorporation into DNA by band-picking/TRFLP or gradient fractionation/qPCR methods. Some results demonstrated 13C incorporation into DNA, indicating growth in air, and other experimental replicates did not. We conclude that microbes outside of water droplets in the air can potentially grow under certain conditions. Based on our data, low biomass is the main limitation for DNA-SIP method of airborne microbes. Current work is investigating this and other limitations, as well as further exploring the potential activity of airborne microbes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B52D..02F
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0452 Instruments and techniques;
- BIOGEOSCIENCES;
- 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCES;
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCES;
- 0478 Pollution: urban;
- regional and global;
- BIOGEOSCIENCES